Review Article Research and Development Aspects on Chemical … · 2019. 7. 31. · Review Article Research and Development Aspects on Chemical Preparation Techniques of Photoanodes

Review ArticleResearch and Development Aspects on Chemical PreparationTechniques of Photoanodes for Dye Sensitized Solar Cells

Nilofar Asim1 Shideh Ahmadi2 M A Alghoul1 F Y Hammadi1

Kasra Saeedfar34 and K Sopian1

1 Solar Energy Research Institute Universiti Kebangsaan Malaysia 43600 Bangi Selangor Malaysia2 NOVITAS School of Electrical and Electronic Engineering Nanyang Technological University Singapore 6397983 School of Chemical Science amp Food Technology Faculty of Science and Technology Universiti Kebangsaan Malaysia43600 Bangi Selangor Malaysia

4Department of Chemistry Faculty of Science K N Toosi University of Technology Tehran Iran

Correspondence should be addressed to Nilofar Asim asimnilofargmailcom and M A Alghoul dralghoulgmailcom

Received 5 August 2013 Revised 19 November 2013 Accepted 21 November 2013 Published 12 January 2014

Academic Editor Mahmoud M El-Nahass

Copyright copy 2014 Nilofar Asim et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The importance of dye sensitized solar cells (DSSCs) as a low-cost and environmentally friendly photovoltaic (PV) technologyhas prompted many researchers to improve its efficiency and durability The realization of these goals is impossible without takinginto account the importance of the materials in DSSCs so the focus on the preparationdeposition methods is essential Thesemethods can be either chemical or physical In this study the chemical applied methods that utilize chemical reaction to synthesizeand deposit the materials are covered and categorized according to their gas phase and liquid phase precursors Film processingtechniques that can be used to enhance the materialsrsquo properties postpreparation are also included for further evaluation in thisstudy However there is a variety of consideration and certain criteria must be taken into account when selecting a specificdeposition method due to the fact that the fabrication conditions vary and are unoptimized

1 Introduction

Dye sensitized solar cells (DSSCs) as a novel photovoltaic(PV) technology have the potential to compete with othertraditional solar cell because they are low-cost and anenvironmental friendly solar cell Their low weight flexi-bility transparency varied color and superior performancein darker conditions make them more popular and haveattracted considerable company investment and governmentfunding

The power conversion efficiency of a DSSC is highlyreliant on its materials which puts them at the forefrontof research However it is not alone in its importance asother areas are equally crucial in the quest to realize a stableefficient and low-cost dye sensitized solar cells [1ndash3]

Although there are many interesting research findingsbased on the development of nanomaterial and new hybridmaterials [4 5] there is still room for progress and the solving

of different issues dealing with dye sensitized solar cells Thepreparation and deposition methods are critical vis-a-vis theproperties of DSSC

Weerasinghe et al [6] have reviewed the technologicaldevelopment of DSSC on flexible polymer substrates payingattention to factors that are imperative to the preparation ofthe slurry film deposition and electrode processing intendedto enhance the mechanical and photovoltaic properties of adevice

The aim of this review is to demonstrate the differentpreparation and deposition methods which have been usedin DSSC emphasizing their advantages and disadvantages inorder to allow a researcher to carefully choose and optimizea given method Chemical methods are further categorizedaccording to their reaction medium or precursors such asgas and liquid We tried to categorize these methods byconsidering this concept although overlapping does occurfrom time to time

Hindawi Publishing CorporationInternational Journal of PhotoenergyVolume 2014 Article ID 518156 21 pageshttpdxdoiorg1011552014518156

2 International Journal of Photoenergy

2 Gas Phase Precursors

21 Chemical Vapor Deposition (CVD) The process that iscalled chemical vapor deposition (CVD) of films and coatingsis the result of chemical reactions that occur between thegaseous reactant close to or adjacent to the surface of a heatedsubstrate (Figure 1) The flexible nature of CVD makes it oneof the preferredmethods of thin filmdeposition and coatingsThe applications of CVD coated thin films are but not limitedto semiconductors for microelectronics optoelectronicsenergy conversion devices dielectrics for microelectronicsrefractory ceramic materials for hard coatings corrosionprotection oxidation or as diffusion barriers metallic filmsfor microelectronics and for protective coatings and fiberproduction and coating [7]

211 Advantages and Disadvantages of CVD On top of itscomplex chemical system some of the advantages of CVDsare [7] as follows

(a) Being able to produce extremely dense and purematerials and allowing manipulation at the atomic ornanometer scales

(b) The films are highly uniform and have good repro-ducibility and adhesion with acceptable depositionrates

(c) Due to its good throwing power and nonline of sightnature it can be used to uniformly coat complex-shaped components and deposit filmswith reasonableconformal coverage which is significantly advanta-geous compared to the physical vapor deposition(PVD) processes

(d) Properties such as crystal structure surface mor-phology and orientation of the products can bemanipulated and customized via the CVDrsquos processparameters

(e) It is capable of producing a variety of coatings suchas single layer multilayer composite nanostructuredand functionally graded coating materials along withwell-controlled dimension and unique structure atlow processing temperatures

(f) The rate of deposition can be readily adjusted Lowdeposition rates are favored for the growth of epitaxialthin films formicroelectronic applications while highdeposition rates are preferred for the deposition ofthick protective coatings

(g) The processing cost for the conventional CVD tech-nique is quite low

(h) The CVD technique allows the usage of a wide varietyof chemical precursors such as halides hydrides andorganometallics which enables the deposition of alarge spectrum of materials that encompasses metalscarbides nitrides oxides sulphides IIIndashV and IIndashVImaterials

(i) The low deposition temperatures allow the desiredphases to be deposited in-situ at low energies via

Heater

Film

Susceptor Substrate

X2 (g)AX2 (g)

AB2 (s) or (1)

Figure 1 A schematic diagram of the CVD coating [7]

vapor phase reactions or nucleation and growthon the substratersquos surface This in turn allows thedeposition of refractorymaterials at a fraction of theirrespective melting temperatures

However the drawbacks of this technique include the follow-ing

(a) the inherent chemical and safety hazards that mightbe instigated by the use of toxic corrosive flammableandor explosive precursor gases Recently howeverthese issues have been mitigated by using variantsof CVD methods such as electrostatic spray-assistedvapor deposition (ESAVD) and combustion chemicalvapor deposition (CCVD) methods which employmore environmental-friendly precursors

(b) the difficulty encountered when trying to depositmulticomponent materials with well-controlled stoi-chiometry via multisource precursors due to the factthat different precursors adhere to different vaporiza-tion rates However this limitation can be negated viathe utilization of single source chemical precursors

(c) the high level of sophistication in the reactor orvacuum system in CVD variants such as low pressureor ultrahigh vacuumCVD plasma-assistedCVD andphoto-assisted CVD tends will inevitably increase thecost of production However there are exceptionsto this case such as aerosol assisted chemical vapordeposition (AACVD) and flame-assisted chemicalvapor deposition (FACVD) where it might be aviable alternative that guarantees low productioncosts [7]

212 Variants of CVDMethods Both the conventional CVDand thermal activated CVD (TACVD) rely upon thermalenergy to activate chemical reactions However other sourcesof energy are also viable for this purpose The advancementsand uniqueness of different variants of the CVD method arediscussed and detailed by Choy [7] while Figure 2 representsthe relationship between different parameters and coatingproperties

In all of the CVD processes several basic functions mustbe provided This includes free movement of the reactantsanddiluents gases to the deposition surface utilizing differentsource to provide reactantrsquos activation energy and maintain

International Journal of Photoenergy 3

Process parameters

∙ Type of precursor∙ Gas ratio∙ Substrate Tdeposition T∙ Pressure

∙ Flow rate∙ Deposition time∙ Reactor geometry

Coating properties

∙ Nucleation and growth∙ Deposition rate

∙ Compositionstoichiometry

∙ Uniformity and adhesion∙ Physicalchemicalelectricalopticalmagneticalmechanicalproperties

CVD phenomena

∙ Thermodynamics

∙ Chemical kinetics (gas

phasesurface)

∙ Mass transport

∙ Microstructure

∙ Coating thickness

Figure 2 A schematic representation of the relationship of process parameters CVD phenomena and coating properties [7]

a specific system pressure and temperature optimizing thechemical deposition method and the complete removal ofby-product gasesThe provisions of these functions howeverrequire adequate control high effectiveness and foolproofsafety

Atmospheric-pressure CVD (APCVD) uses the low-temperature (below 600∘C) rotary vertical-flow reactors anda continuous in-line conveyorized reactors with various gasdistribution featuresmostly for depositing oxides binary andternary silicate glass coatings for solid-state devices Low-pressure CVD (LPCVD) (typically 01ndash10 torr) in the low-mid- or high-temperature range uses resistance-heated hot-wall reactors of tubular bell-jar or close-spaced designsThe advantage and wide usage of LPCVD over APCVD areattributed to the fact that in LPCVD no carrier gases areneeded particle contamination is reduced and film unifor-mity and conformity are superior in conventional APCVDreactor systems [8]

In a metalorganic chemical vapor deposition (MOCVD)the copyrolysis of various combinations of organometalliccompounds and hydrides is employed for the growth ofthin epitaxial layers of compound semiconducting materialsComposite layers of accurately controlled thickness anddopant profile are required to produce structures of optimaldesigns for device fabrication [9]

Photo-enhanced chemical vapor deposition (PHCVD)uses electromagnetic radiation usually short-wave ultravioletradiation in order to activate the reactants in the gas orvapor phase The selective absorption of photonic energy

by the reactant molecules or atoms initiates the process byforming reactive free-radical species that will then interact toform a desired film product In laser-induced chemical vapordeposition (LCVD) a laser beam prepares a highly localizedheat in a substrate which will then induce film deposition viaCVD surface reactions [8] Table 1 presents some of researchresults on materialsrsquo preparation using CVD methods forDSSC application

22 Atomic Layer Deposition (ALD) The atomic layer depo-sition (ALD) method is considered a self-imposed filmgrowth method that is defined by the alternating exposureof the chemical species in a layer-by-layer manner ALDis divided into four crucial steps (1) the exposure of themetal precursor (2) evacuation or purging of the precursorsand any by products from the chamber (3) exposure of theother reactant species (nonmetal precursor) for examplenitrogen containing reducing agents for nitrides or reduc-ing agents for metals and (4) evacuation or purging ofthe reactants and by product molecules from the chamber(Figure 3) The most imperative requirement in the initialstep is self-imposed limitation on the precursor moleculersquosadsorption process In most cases this requirement is metvia the ligands that are linked to the metal atoms presentin the precursors which includes halogen or organic lig-ands This will inevitably curtail further adsorption bythe metal precursor via the passivation of the adsorptionsites on the saturation coverage of one monolayer or less


Table 1 Some research results on DSSC using different CVD methods

Materials Method Efficiency (120578) ReferenceGraphene-based multiwalled carbonnanotubes (GMWNTs)

Drop casting and low pressure chemical vapordeposition (LPCVD) 30 [130]

Nanostructured TiO2 Flat-flame chemical vapor deposition gt4 [131]

Graphene-CoS Low pressure thermal chemical vapordeposition (LPCVD) 342 [78]

ZnOTiO2Thermal chemical vapor deposition mdash [132]

ZnO nanostructures coated on verticallyaligned carbon nanotubes (CNTs) Thermal chemical vapor deposition 194 [133]

MWNTs (multiwall carbon nanotubes) Thermal chemical vapor deposition 099 [134]

TiO2 thin film Metalorganic chemical vapor deposition(MOCVD) mdash [135]

InN deposited over TiO2 nanoparticle(NP) films

Metalorganic chemical vapor deposition(MOCVD) 707 [136]

Mesoporous TiO2 with polymerelectrolyte Initiated chemical vapor deposition (iCVD) 28 [137]

TiO2 thin films Atmospheric pressure chemical vapordeposition (APCVD) mdash [138]

Nanocrystalline TiO2 thin films Chemical vapor deposition 017 [139]

Precursor

Byproduct

Reactant

Step 1 precursor exposure Step 2 purge

Step 3 reactant exposureStep 4 purge

1 cycle

Figure 3 Atomic layer deposition (ALD) [10]

that is achieved The current trend of downscaling deviceshas propelled ALD to the forefront as one of the pri-mary methods of nanoscale device fabrication due to itssuperiority over conventional techniques such as PVD orCVD

221 Advantages and Limitations ALD is sequential self-limiting surface reaction process that enables atomic layercontrol (angstrom or monolayer level) and excellent confor-mal deposition [11]This aspect results in excellent step cover-age and conformal deposition on high aspect ratio structuresADL can produce continuous smooth and pinhole-free

film It is possible to obtain high quality materials and lowprocessing temperatures with the ALD method

ALD processing also includes enormous substrates andparallel processing of multiple substrates as well Due to thefact that the precursors to the ALD are gas phase moleculesthe entire space will be filled with it regardless of thesubstratersquos geometry The line-of-sight to the substrate vis-a-vis the substrate in this process is also unimportant alongwith problems such as unpredictable vaporization rates ofsolid precursors ALD possesses excellent reproducibility andis capable of producing multilayer structures in a continuousprocess [12 13] ALD is also capable of producing sharpinterfaces and superlattices allowing for the possibility ofinterface modification

One major limitation of the ALD method is its lack ofspeed resulting in only a fraction of a monolayer beingdeposited in a single cycle However the recent developmentshelp the commercial ALD tools in realizing cycle times oflt5 seconds resulting in the deposition of a 100 nm film inless than an hour Recent advances in roll-to-roll ALD areallowing for an even faster throughput

The materials for the films grown by ALD are numerouswhich also includes technologically strategic materials suchas Si Ge and Si

3N4 However certain multicomponent

oxides and metals cannot be grown or deposited by ALDin an economical manner which renders their depositionunfeasible

Another limitation of ALD is that it is confined by the sizeof its reaction chamber In addition due to the fact that it is achemical technique there is always a chance that chemicalresidues from the precursor might remain in the chamberTable 2 presents the results of DSSC prepared using ALDmethods


Table 2 Results of DSSC using ALD method

Materials Method Efficiency (120578) Reference

Al2O3-coated TiO2 (corendashshell)Atomic layer deposition (ALD) 84 [140]

Hafnium oxide (HfO2) and aluminumoxide (Al2O3) on mesoporous TiO2

Atomic layer deposition (ALD) 71 [141]

Al2O3overlayers on porous TiO2 Atomic layer deposition (ALD) mdash [142]Highly ordered and vertically orientedTiO2 nanotube arrays

Template-assisted method using atomic layerdeposition (ALD) and reactive ion etching (RIE) 117 [143]

Resistance heated furnace

Siliconwafers

Exhaust

Quartz tube

HCl H2N2

O2

FlowmetersQuartz boat

Figure 4 Schematic of a thermal oxidation furnace [14]

23 Thermal Oxidation The method of thermal oxidationproduces a thin layer of oxide on a waferrsquos surface It forcesthe diffusion of an oxidizing agent into the wafer at hightemperatures and induces a reaction within it The Deal-Grove model predicts the rate the oxide growth Figure 4shows a thermal oxidation furnace

ZnO nanobelts and nanotetrapods are fabricated via thethermal oxidation reaction technique The process begins byheating the zinc paste that was prepared from zinc powder(purity 999) which was then mixed with a hydrogenperoxide solution (30wt) at a temperature of 1000 ∘Cundernormal atmosphere for a few minutes The best results ofDSSCs were the short circuit current (119869sc) of 125mAcm2the open circuit voltage (119881oc) of 045V a fill factor (FF) of065 and the overall energy conversion efficiency (120578) of068 [15]

ZnO nanonetwork structures with high porosities werefabricated for use in the photoelectrodes of binder-free dye-sensitized solar cells (DSSCs) by the PVD method of DCsputtering followed by thermal oxidationThe nano-networkof Zn was successfully transformed into ZnO without under-going a morphological change through annealing in openatmosphere [16]

Moreover TindashTiO2structure has been used in the fabrica-

tion of numerous TiO2-based devices such as solar cells elec-

trocatalytic electrodes and noble metalndashTiO2ndashTi chemical

sensors Hossein-Babaei and Rahbarpour [17] fabricated TindashTiO2ndashTi and AgndashTiO

2ndashTi structures on a thermally oxidized

titanium chip and analyzed their electronic behaviors atdifferent biasing thermal and atmospheric conditions

3 Liquid Phase Precursor

Due to the fact that the liquid phase chemical methods areconsidered a bottom-up approach the morphology of nano-materials in the thin film can be tuned in order to allow forbetter control of particle size shape size distribution particlecomposition and degree of particle agglomeration while thechemical deposition methods are inexpensive which allowsthe synthesis of thin films materials containing complexchemical compositions Lokhande et al [18] investigatedthe deposition of nanocrystalline metal oxide thin filmsusing chemical methods and the relation of their respectivemorphology in their various applications

31 Electrochemical Deposition (ECD) The electrochemicaldeposition ofmetals and alloys revolves around the reductionof metal ions from aqueous organic and fused-salt elec-trolytes (see Figure 5) This process is represented by (1)

M119911+solution + 119911e 997888rarr Mlattice (1)

This is achievable via two different processes (1) an electrode-position process where 119911 electrons (e) are provided by anexternal power supply and (2) an electroless (autocatalytic)deposition process where a reducing agent in the solutionis the electron source (sans an external power supply) Bothprocesses are representative of electrochemical deposition[19]

The electrochemical method counts among the simplestand most effective method of fabricating 1D semiconduc-tor nanostructures Among variants of the electrochemicalmethod in preparing oriented 1D film are template-assistedelectrochemical synthesis and direct electrochemical growthvia capping reagents [20] Among the advantages of the elec-trochemical methods is the ability to customize and controlthe compositions andmorphologies of nanostructuredmate-rials Different types of electrochemical deposition such aselectroplating electrolytic anodization and electrophoreticdeposition can be used for the synthesis of materials InElectrophoretic Deposition dissociated colloidal cations andanions disperses onto a conductive substrate After applyingan electric field the colloidal charged particles migrate tothe substrate get discharged and form a film Similar tothermal oxidation in Electrolytic anodization an oxide filmis formed on the substrate the difference is that the anode isoxidized because of the negative ions in the electrolyte andforms a nonporous and well-adhering oxide or a hydrated


Potentiostatgalvanostat

Reference electrode

Working electrodeCounter electrode

Figure 5 The schematic representation of the electrodepositionsystem [21]

oxide coating on semiconductors and on a few specificmetals During oxidation the hydrogen gas evolves at thecathode Electroplating can be used for the deposition ofmetallic coatings on the cathodersquos substrate when applyingan electrical current to an electrolytic cell consisting of ananode cathode and an electrolyte solution (containing themetal ions) [8] Table 3 summarizes the different type ofelectrochemical synthesis that is employed for DSSC

32 SolvothermalHydrothermal Methods Both the solvo-thermal and hydrothermal methods are effective tools inthe generalization and systematic control of the syntheses ofnanomorphologies Figure 6 shows the typical autoclave forsolvothermalhydrothermal synthesis

The solvothermalhydrothermal methods are importanttechnologies with regard to the production of semicon-ductor nanowires at low temperatures Zou et al [22]discussed nanowire growth from mainly four aspects inthe solvothermalhydrothermal processes (1) materials withhighly anisotropic crystal structures (2) coordination direct-ingmixed solvents (3) surfactantscapping reagents and (4)reactions at relatively high temperatures

Both the hydrothermal and solvothermal methods havesome poignant differences These differences include the factthat the solvothermal method (using non-water as a solvent)can practically halt oxidization a factor that is especiallyimperative to the synthesis of a variety of nonoxides [22]

ldquoHydrothermal synthesisrdquo is defined by the heteroge-neous reactions in aqueous media above 100∘C at 1 barof pressure [24] It remains one of the preferred methodsin fabricating pure fine oxide powders Figure 7 details theschematic of the hydrothermal synthesis

For hydrothermal experiments the prerequisites for thestarting materials are (i) knowing the composition (ii) beingas homogeneous as possible (iii) being as pure as possibleand (iv) being as fine as possible [26] Somiya and Roy [26]

Spring

Stainless steellid

Teflon liner

Precursorsolution

Stainless steelautoclave

Figure 6 Schematic diagram of the autoclave used in solvother-malhydrothermal synthesis [23]

described some of different types of hydrothermal synthesismethods (see Table 4)

321 Advantages and Disadvantages of HydrothermalSolvo-thermal Synthesis The advantages include the following

(1) Most of thematerials that are involved can be inducedto solubility via heat and pressure applied to thesystem up to its critical point

(2) It offers a significant enhancement to the chemicalactivities of the reactant the possibility to replace thesolid-state synthesis andmaterials whichmay not beobtained via solid-state reaction but may be preparedthrough hydrothermalsolvothermal synthesis

(3) Products of intermediate state metastable state andspecific phase may be easily produced and novelcompounds of metastable state and other specificcondensed state may be synthesized

(4) Simplified and precise control of the size shapedistribution and crystallinity of the end product viathe adjustment of parameters such as reaction tem-peratures and time the types of solvents surfactantsand precursors can be achieved

(5) Substances that are low in melting points and high invapor pressures and tendency towards pyrolysis willbe obtained

The disadvantages of hydrothermalsolvothermal synthesisare as follows

(1) the need of expensive autoclaves(2) safety issues during the reaction process(3) impossibility of observing the reaction process

(ldquoblack boxrdquo) [27]

Researchers have used both the hydrothermal and solvother-mal methods extensively Some of most recent researches


Table 3 Different electrochemical deposition methods used in DSSC

Materials Method Efficiency (120578) ReferencePorous ZnO on carbon nanotube (CNT)coated polymer Electrochemical deposition 25 [144]

Vertical ZnO nanotube (ZNT) Electrochemical deposition followed by a selectiveetching process 101 [145]

Well-crystallined ZnO-eosin Y hybrid thinfilms Two-step cathodic electrodeposition 021 [146]

Crystalline nanoporous layers of ZnO Gas template electrodeposition 21 [147]

ZnOdye hybrid thin films Cathodic electrodeposition (electrochemicallyself-assembled) mdash [148]

ZnO nanobelt array films Electrodeposition method with liquid crystaltemplate 26 [149]

ZnO porous film on a plastic substrate Electrophoresis deposition (EPD) process withUV-O3 treatment 404 [150]

ZnO photoanode on plastic Electrophoretic deposition method 417 [151]Nanowires and hierarchical ZnOnanostructures

Anodization and subsequent electrochemicaldeposition mdash [152]

Branched hierarchical ZnO nanowire arrays Two-step electrochemical deposition process 088 [153]Mesoporous platinum Electrochemical deposition 76 [154]Platinumgraphene hybrid film Electrochemical deposition 788 [155]Graphene-PtITO (ITO-PG) Electrochemical deposition 757 [156]Platinum nanoparticle Electrochemical deposition 64 [157]Thin Pt counter electrode Pulsed electrodeposition method 6 [158]Platinum nanoparticles on plastic substrates Electrophoretic deposition 58 [159]Platinum (Pt) layer on ITO Electroless deposition 646 [160]Composite (PProDOT-Et2Pt) Electropolymerization 665 [161]Closely packed titania nanoparticles Electrochemical deposition 627 [162]Coaxial TiO2ZnO nanotube arrays Electrochemical deposition 28 [163](1198621198971198744

minus-PEDOTTiO2FTO) Electrochemical deposition 478 [164]Nanocrystalline anatase TiO2 Reductive electrodeposition 51 [165]TiO2dye hybrid films Anodic electrodeposition mdash [166]Ordered titanate nanotube (TNT) films Electrophoretic deposition 379 [167]Titanate nanotubes Hydrothermal process and electrophoretic deposition 671 [168]Mesoporous TiO2 film on a titanium (Ti) foil Electrophoretic deposition 65 [169]Mesoporous TiO2 photoanode film onplastic substrate Electrophoretic deposition 437 [170]

TiO2-B nanoribbon films Electrophoretic deposition 087 [171]Highly ordered TiO2 nanotube arrays Electrophoretic deposition 628 [172]Titanium oxide (TiO

119909

) thin films Cathodic electrolysis 233 [173]

Nanostructured TiO2 films Plasma electrolytic oxidation combined withchemical and thermal post-treatments 2194 [174]

Combined TiO2 structure with nanotubesand nanoparticles Electrochemical anodization 575 [175]

Titanium dioxide (TiO2) nanotube arrays Anodizing 438 [176]Non-annealed anatase TiO2 film Anodizing and sputtering mdash [177]Titania nanotube arrays Electrochemical anodization mdash [178]TiO2 nanotube arrays Anodizing detachment and transfer method 178 [179]Aligned high-aspect ratio TiO2 nanotubebundles Rapid breakdown anodizing (electrochemical) mdash [180]

Well-aligned TiO2 nanotube arrays Electrochemical etching 213 [181]


Table 3 Continued


TiO2-nanotube array electrodeArc ion plating (AIP) deposition and anodicallyoxidizing 188 [182]

Nanocrystalline TiO2 filmsMicroplasma oxidation (MPO) method (processcombines electrochemical oxidation with ahigh-voltage spark treatment in an electrolyte bath)

0092 [183]

Nanostructured TiO2 films Plasma electrolytic oxidation (PEO)combined withchemical and thermal posttreatments 2194 [174]

Functionalized and nonfunctionalizedfullerene thin films on ITO glasses

Electrolytic micelle disruption method (theelectrolysis method) mdash [184]

Arborous structure SnO2 porous films on Tisubstrate Pulse-potential technique (electrodeposition) 047 [185]

Crystalline CuSCN films Cathodic electrodeposition mdash [186]

(PProDOT-Et2) Electrochemical polymerization(electropolymerization) 788 [187]

High conductive transparent substrates werefabricated with nickel grids Electroplating process 43 [188]

Polyaniline nanofibercarbon film Electrochemical deposition 685 [189]Polyaniline nanofibers Pulse electropolymerization 513 [190]

MineralizerMineralizer Mineralizer

Solidphase

Solidphase

Solidphase

SolventSolventSolvent

Starting materials

Heating Pressure

Dissolution

Doposition

Figure 7 Schematic of the hydrothermal synthesis procedure [25]

[28ndash32] have used the hydrothermal method for the prepa-ration of nanoparticles of TiO

2and ZnO and their com-

posites for DSSC application Feng et al [33] employedthe hydrothermal method followed by a fast dip coatingfor the synthesis of ZnOTiO

2core-shell long nanowire

arrays Their DSSC achieved an efficiency of 38 Otherresearchers used mix solvents for the hydrolysis of TiCl

4

The experimental test of prepared DSSC from the resultednanocrystalline TiO

2showed the high value efficiency (120578 =

913) [34] Capping agents-assisted hydrothermal methodhas been employed for the preparation of ZnO nanostruc-tures for DSSC application [35] The application of thesolvothermal method using templates for the synthesis ofmesoporous titania hollow spheres resulted in a DSSC with316 efficiency

322 Microwave Irradiation The hydrothermal methodplays a defining role in the shaping of the microstructures

of TiO2 However conventional hydrothermal processing is

usually reliant upon high temperatures and pressures alongwith extended processing times and complex proceduresfor the synthesis of TiO

2nanocrystals [36 37] This paves

the way for microwave processing of inorganic compoundswhich forms an attractive field inmodernmaterial science Tothis end many inorganic materials had been synthesized viamicrowave ovens [38ndash42] mostly through rapid microwave-material interactions This technique is also viable for thesynthesis of nanosized TiO

2powder possessing high degrees

of crystallinity and monodispersed crystallites [43ndash45]It has also been reported that the integration of

microwave irradiation has effectively enhanced the efficiencyof the hydrothermal method vis-a-vis the preparation ofinorganic materials [46ndash53] Microwave-assisted method hasthe unique advantage of uniform rapid and volumetricheating compared to its conventional counterpart More-over microwave-assisted hydrothermal method significantlyreduces both the processing time and temperatures which


Table 4 Hydrothermal synthesis

Hydrothermal crystal growthHydrothermal treatmentHydrothermal alternationHydrothermal dehydrationHydrothermal extractionHydrothermal reaction sinteringHydrothermal sinteringCorrosion reactionHydrothermal oxidationHydrothermal precipitationmdashhydrothermal crystallizationHydrothermal decompositionHydrothermal hydrolysismdashhydrothermal precipitationHydrothermal electrochemical reactionHydrothermal mechanochemical reactionHydrothermal + ultrasonicHydrothermal + microwave

results in rapid crystallization and the simplification ofthe whole process [37] In most cases TiO

2nanoparticles

are produced via the hydrothermal treatment A multi-mode microwave heating system operating at a frequencyof 28GHz is utilized in order to induce rapid process-ing [45] The synthesis of ZnO nanorods electrodes uti-lizing microwaves also demonstrated marked performanceimprovements [54]

It has been determined that the usage of organometallic orinorganic precursors inmicrowave-assistedmethods resultedin remarkable improvements in all aspects This is demon-strated in the work of Bhatte and coworkers [55] where theyemployed Zn (CH

3COO)

2as an additive-free synthesis of

nanocrystalline zinc oxide via themicrowave techniqueAlsoBrahma and Shivashankar [56] reported the utilization ofthe microwave method for depositing thin films and thickcoatings of metal oxides via a liquid medium involving themicrowave irradiation of an inorganic complex solution andzinc acetylacetonate in a dielectric solvent In this workZnO nanoflowers and ZnGly micro- and nanoplates aresynthesized via a very rapid and convenient microwave-assisted polyol method ZnO nanoflower based solar cellsensitized with N719 dye demonstrated the maximum con-version efficiency of 103 [57]

Meanwhile it must be considered that microwave tech-nique can be used with other methods such as chemical bathdeposition which requires heating and calcination

323 Ultrasonic Technique The method of sonochemicalprocessing has proven itself useful in fabricating novelmaterials with unique properties [58 59] The workingprinciple behind the chemical effect of ultrasound is derivedfrom acoustic cavitation which is the formation growthand implosive collapse of bubbles in a liquid This in turngenerates localized hot spots via adiabatic compression orshock wave formation within the gas phase of the collapsing

bubbleThese formed hot spots are demonstrated to possess atransient temperature of about 5000K pressure of 1800 atmand cooling rates exceeding 108Ksminus1 [59] The specific appli-cation of ultrasound in the synthesis of a variety of materialshas been analyzed by Suslick and Price [60]

Wang et al [61] employed ultrasonic waves to fabricatemesoporous TiO

2under different conditions for DSSC appli-

cations

33 Chemical Bath Deposition (CBD) The chemical bathdeposition (CBD) method also known as controlled precip-itation or solution growth method or quite simply chemicaldeposition has recently been vaunted as a viable method forthe deposition of both metal chalcogenide and metal oxidethin films CBD is essentially a simplemethod requiring onlya hot plate with a magnetic stirrer The precursor chemicalsare widely available and cost little The CBD method allowsthe coating of a large number of substrates in a single cycleprovided that a proper jig is designed to do so In the contextof this method the electrical conductivity of the substrate isunimportant Any part of the surface that is insoluble and canbe accessed by the solution will make a suitable depositionsubstrate The deposition process happens at low tempera-tures which circumvents the occurrence of oxidation andcorrosion of metallic substrates Chemical deposition usuallyresults in the absence of pinholes and uniform deposits areeasily obtained since their basic building blocks are ionsinstead of atomsThe parameters are easily controlled whichallows us to gain better orientations and grain structuresThe formation of the film occurs when the ionic productdominates the solubility product [8 9] The whole setup ofthis process is detailed in Figure 8

The chemical bath deposition (CBD) method has beenemployed for the preparation of nanostructures ZnO [62]garland like ZnO nanorods [63] nanobeads of zinc oxide[64] cauliflower-like ZnO Films [65] mesoporous F-dopedZnO prism array [66] ZnO nanorod arrays [67] ZnOnanocomposites [68] and ZnO nanoarray [69]

Zumeta et al and Vigil et al [50 70] used microwave-activated chemical-bath deposition (MW-CBD) for thepreparation of TiO

2forDSSCThey claimed that the resulting

TiO2has superior electrical and mechanical properties

PVP capped Pt nanoclusters on ITO glass and platinumon metallic sheets were both prepared using the chemicaldeposition method and have been used in DSSC as counterelectrodes [72 73]

Li et al [74] have synthesized SrSnO3nanoparticles and

employed them for the first time as electrode materialsin DSSC using CBD The prepared DSSC has achieved anefficiency of 102

34 Successive Ionic Layer Adsorption and Reaction (SILAR)Method Successive ionic layer adsorption and reaction(SILAR) is a recently developed method for the depositionof metal chalcogenide thin films although it has undergoneless scrutiny by researchers [75 76] The method is basedon the immersion of a substrate into anionic and cationicprecursors followed by rinsing of the substrate between every


Rotor

Precursor solution

Oil filled bath

Magnetic niddal

Heater

StandSubstrate

Thermometer

Thin film

Figure 8 Schematic representation of chemical bath depositionmethod [71]

immersion in double distilled water in order to circumventhomogeneous precipitation Figure 9 graphically summarizesthis method During the immersion into a cationic precursorcations are adsorbed onto the substratersquos surface The actof rinsing after immersion will separate the unabsorbed orexcess ions while simultaneously preventing homogeneousprecipitation Similarly when immersed in an anionic pre-cursor solution the anions will react with the preadsorbedcations The remaining unreactedpowdery material can beexpelled via rinsing The whole process of immersion andrinsing in both the cationic and anionic precursor is regardedas one full cycle After a few repetitions of these cycles amultilayer film of desired thickness would be formed Thequality and thickness of these respective films are highlydependent on the preparation parameters A review byPathan and Lokhande [77] outlines the advantages of SILARover the CBD method In the former the deposition of asufficiently thick film requires an extended period of timewhichmakes it crucial that it is operated withmicroprocessoror computer [18]

Das et al [78] have prepared CoS-implanted graphene(G-CoS) film electrode using chemical vapor deposition andSILAR for DSSC The prepared electrode was characterizedin a dye sensitized solar cells (DSSCs) It reached betterefficiency 120578 = 342 while 119869sc (mAcm2) 119881oc (V) and FF() was 128 072 and 364 respectively

Thin ZnSe layers were deposited on ZnOnanowires usingSILARmethod byChung et al [79] forDSSC applicationThefacilitation of electron transfer increased the 119869sc which wasfollowed by improved efficiency

35 Spray Pyrolysis Method Spray pyrolysis is regarded asone of the most attractive and promising film preparationmethods It basically mirrors a film processing techniquecalled thepyrosol technique where a source solution is

CationsAnions

Figure 9 Schematic representation of SILAR method [71]

sprayed onto a heated substrate for it to be deposited in theform of a film The mechanism of the process is as followsThe source solution is atomized where small droplets splashand vaporize on a substrate which results in the formation ofa dry precipitate and thermal decomposition [80] Figure 10shows a schematic of the whole process

351 Advantage and Disadvantages Advantage and Disad-vantages are as follows

(i) does not require high quality targets or substrates(ii) being of low cost(iii) does not require a UHV system(iv) continuously produces the material(v) chemical reaction occurs within the created micron

to submicron sized liquid dropletsmdasha microcapsulereactor

The technique is quite empirical with a number of variablesthat can affect the final product such as solute concentrationatomization technique temperature temperature gradientresidence time in furnace and carrier gases [80] Table 5represents research results using SPD method in preparationof DSSC Figure 11 represents the comparison between spincoating and spray pyrolysis methods

36 Sol-Gel Coating The sol-gel process is also known asthe chemical solution deposition and it is classified as a wetchemical technique that is widely being applied in fields ofmaterials science and ceramic engineering (Figure 12) It ismostly used for materialsrsquo synthesis (typically a metal oxide)initiated from a chemical solution that acts as the precursorfor an integrated network (or gel) of discrete particles ornetwork polymers Some common precursors include metalalkoxides and chlorides which are pegged to undergo mul-tiple forms of hydrolysis and polycondensation reactionsMetal oxides are formed via the linkage of metal ionswith oxo (MndashOndashM) or hydroxo (MndashOHndashM) bridges whichresults in a metal-oxo or metal-hydroxo polymers forming in


Exhaustsystem

Nozzle support

Gas flowcontroller

Nozzle

Depositionchamber

Substrates

Iron plate

HeaterThermocouple

Temperaturecontroller

Powersupply

Mechanical system

Nozzle shaft

Solution

Solution container

Solution flowcontainer

Figure 10 Schematic representation of spray pyrolysis method [18]

Table 5 SPD methods in preparation of DSSC

Materials Method Efficiency (120578) ReferenceFluorine-doped tin oxide (FTO)films coated on indium-tin oxide(ITO) films

Spray pyrolysis deposition (SPD) 37 [191 192]

ITO-Pt semiconductor powdercontaining nanoscale noble metalparticles

Spray pyrolysis mdash [193]

TiO2 blocking layer Spray pyrolysis mdash [194 195]Porous TiO2 films Spray pyrolysis deposition 32ndash 51 [81 196]TiO2 nanocrystalline electrode Atomized spray pyrolysis (ASP) 82 [197]Nb2O5 blocking layer Spray pyrolysis 335 [198]Boron-doped zinc oxide (B

119899

ZnO)electrode Spray pyrolysis deposition 153 [199]

ZnO nanostructures Spray pyrolysis 47 [200]

a solutionThus the sol gravitates towards a gel-like diphasicsystem of both liquid and solid whose morphologies rangesfrom discrete particles to continuous polymer networks Thesol-gel technique is considered as a bridge for nanoparticlesin the DSSC working electrodes such as TiO

2nanoparticles

(P25 and P90) on polyethylene naphthalate (PEN) plasticsheet [82] and metal oxide semiconductor nanostructuredsuch as zinc titanate (ZT) zinc oxide (ZO) and titaniumdioxide (TD)The highest loading amount of dye and the bestinteraction between the semiconductor and dye are related to

ZOwhich has higher efficiency than the other cells Due to itshigh electron conductivity ZnO has the potential to enhancedye adsorption and highlight transmittance of a compositefilm [83] Generally the sol-gel process results in a highly pureproduct homogenous high adhesion and strength and lowtemperature processing

The Sol-gel method is one of the most used meth-ods for materials preparation in DSSC Certain recentresearch achievements using the sol-gel methods includeTiO2film and nanoparticles ZnO ZT preparation for DSSC


Spin coating

Drying

Pre-sintering

Stacking

Sintering and necking

(a) Spin coating technique

Spraying

Stacking

Pyrolyzing and necking

(b) SPD technique

Figure 11 Comparison between spin coating and SPD methods [81]

Xerogel filmHeat

Heat

Coating

Coating

GellingHydrolysis

polymerisation

Sol

Precipitating

Uniform particles

Wet gel

Dense film

Evaporation

Extraction ofsolvent

Aerogel

FurnaceCeramic fibres

Spinning

Metalalkoxidesolution

Figure 12 Schematic of sol-gel procedure and their products [84]


application [82 83 85ndash90] Some researchers employ the sol-gelmethod in combinationwith physical depositionmethodssuch as dip coating spin coating and electrospinning inorder to synthesis TiO

2 doped TiO

2 and TiO

2composites

[90ndash95]Kwon et al [96] used the sol-gel combustion method for

the preparation of nanoporous F-doped tin dioxide filmsTheresulting DSSC managed to achieve an efficiency of 12

37 Template Method Among the many methods that can beused to fabricate ordered porous films (sputtering chemicalvapor deposition (CVD) spray pyrolysis and sol-gel process)the template method is the one that is mostly used due tothe fact that the porersquos dimensions are determined by the sizeof the ordered template beads [97ndash100] The result of thismethod is a material that is homogenous pure possessingnovel morphology structure and properties

However it is commonly acknowledged that withoutbeing combined with another physical and chemical methodthe end product of the template method is not up to parThe combination of template growth and sol-gel coatingresults in the fabrication of fine nanostructure of desiredfeatures [101ndash110] Jiu et al [102] reported template growthof porous TiO

2films with mixed polymers of Pluronic F-

127 and cetyltrimethylammonium bromide Zukalova et al[111] reported a similar structure with Pluronic P-123 Bothworks produce end products with very high surface areasbut small pore diameters of 4ndash7 nm [102] and 6ndash8 nm [101]respectively

Dionigi et al presented a colloidal composite consistingof monodispersed polystyrene (PS) coated with a titaniumoxide precursor named TALH that acts as a ldquostructuredirectorrdquo for the fabrication of TiO

2films [112] Meanwhile

Meng et al assembled a highly ordered three-dimensionalporous structurewith commercial nanosized crystalline TiO

2

particles via a cooperative method where the fabrication ofthe template and the infiltration of its voids occur simulta-neously [113] Also highly ordered TiO

2porous films were

synthesized via a single-step assembly method where theporous structures were prepared using polystyrene micro-spheres with diameters [114] Liu et al prepared porous ZnOthin films that are assembled by multilayer PS templatesachievable by repeatedly employing the dip coating method[115] Table 6 shows the result for DSSC prepared usingtemplate method

38 Self-Assembly Self-assembled nanosphere monolayersform the templates of nanosphere lithography and can usuallybe fabricated with techniques such as drop coating or spincoating [116ndash118] of polystyrene (PS) latex nanospheresHowever the difficulty in producing a low-defect and large-area nanosphere monolayer using this method is also noted[119]

Jhang et al [119] have used spin-coating that in com-bination with the water transfer technique produced self-assembled layer for preparation of nanostructured Pt counterelectrodesThis electrode achieved119881oc (V) 119869sc (mAcm2) FFand 120578 of 071 1445 070 and 718 respectively Template-free

chemically induced self-transformation (CIST) method hasemployed by Yu et al [120] for preparation of hollow anataseTiO2spheres The fabricated DSSC has been reached at 119869sc

(mAcm2) 119881oc (V) FF () and 120578 () of 147 0599 0547and 482 respectivelyMesostructured titania thick films havebeen synthesized employing of evaporation-induced self-assembly using nonionic triblock copolymers as templatingagents by Malfatti et al [121]

39 Mechanical Methods There are many mechanical tech-niques such as spraying spinning dipping and draining flowcoating and roller coating which are done for depositingcoatings from a liquid media that subsequently reactedchemically to form the inorganic thin film product Thesetechniques are also classified in different ways compared tothe physical depositionmethod which requires a whole otherdiscussion

4 Film Processing Techniques

There are some techniques which can be used to enhancethe materialsrsquo properties after their preparation as well astheir application for the preparation mix with some otherpreparation methods namely microwave or ultrasonic

The deposited electrode materials on flexible substratelike polymers require an additional processing step toimprove the necessary interparticle contact for their effectiveperformance as an electrode material as well as to improvethe mechanical stability namely good film-substrate adhe-sion Organic binders were used in making flexible DSSCsbut the absence of high temperature sintering of the metaloxide filmonpolymer substrates resulted in incomplete neck-ing of the particles due to the presence of residual organics inthe film [122] UVozone and UV radiation treatments of thedeposited metal oxide films were used by several groups as amethod for eliminating adsorbed organic impurities on thesurface of metal oxide films and improving the interparticleconnection as another low temperature sintering method forflexible DSSCs [6 123ndash127]

In order to realize the selective heating of organic-inorganic composite films microwave processing seems tobe the most promising choice Uchida et al [128] used a28GHz microwave irradiation process to produce a flexibleDSSC This particular technique is also applicable in thefabrication of PET-ITO film electrodes A photoelectronenergy conversion efficiency of 216 is realized for all-plasticcell fabricated by the 28GHzmicrowave irradiation at 10 kWfor 5 minutes

Gan et al [129] succeeding in fabricating a hybrid ZnOnanowireTiO

2nanoparticle photoanodes for DSSCs using

an ultrasonic irradiation assisted dip-coating method Thegap-filling efficiency of TiO

2nanoparticles into the interstice

voids of the ZnO nanowires was enhanced with the assis-tance of ultrasonic irradiation which results in an increaseof the total surface area along with the light harvestingefficiency for the hybrid electrode The effects of the ultra-sonic treatment on the microstructure the sensitization and


Table 6 Some research work on DSSC that used template method

Materials Method Efficiency (120578) ReferenceHigh-crystalline TiO2nanoparticles as a thin-film Mixed template of copolymer and surfactant 824 [102]

Mesoporous titania nanocrystals Sol-gel synthesis using surfactant as template 408 [201]Organized mesoporous TiO2films

Supramoleculartemplating with anamphiphilictriblock copolymer mdash [111]

Multilayered mesoporous TiO2films

Supramolecular templating and layer-by-layerdeposition 512 [202]

Nanocrystallinemesoporoustitania

Surfactant-assisted templating method anddoctor-blading technique 806 [203]

Ordered nanoporous TiO2Different silica templates and the squeezeprinting technique 36 [204]

Hollow spherical TiO2 Colloidal carbon spheres as templates 564 [205]Mesoporous anatase-TiO2 Sol-gel using soft template and a hard template 671 [206]Anatase TiO2 hollow spheres Chemical template method 379 [207]Ordered porous TiO2 thin films Colloid crystal template 1269 [208]

Mesoporous TiO2Sol-gel using water miscible ionic liquidtemplate mdash [209]

Porous TiO2 films Templated sol-gel method mdash [210]Mesoporous nanocrystallineTiO2 films

Hydrolysis-limited solndashgel process using blockcopolymer as template 031 [211]

Center hollow ZnO and TiO2nanotubes arrays

Electrodeposition chemical etching andsol-gel process assisted by templates 12 [212]

Ferrocene-derivatized orderedmesoporous carbon Hard template method 789 [213]

Ordered mesoporous carbon(OMC)

Evaporation-induced triconstituent coassemblymethod using soft-template method employingtriblock copolymer

746 [214]

MWCNTmesoporous carbonnanofibers composites

Electrospinning template etching and thermalprocess 635 [215]

Nanoporous NiO films NiCl2 in waterethanol mixed solution usingtriblock copolymers as template mdash [216]

Hollow silver microspheres Chemical deposition using sacrificialtemplating method mdash [217]

the performance of hybrid ZnO NWTiO2NP electrodes

were thoroughly analyzed

5 Lessons Learned

Taking into account the contents that are presented it can besurmised that choosing an appropriate method is incumbentupon its parameters For example if the deposition rate isthe primary parameter being considered then the ALD andSILAR methods are ruled out as they are detrimental in thecontext of deposition rates If safety is of vital importancethen the use of CVD ALD and solvothermalhydrothermalmethods is not recommended Furthermore if one needsto synthesize materials that are unobtainable via solid-statereaction the usage of solvothermalhydrothermal methodmight be most suitable

The preparation of thin films is highly reliant on theminute control of the materials at a molecular and atomiclevel which encompasses surface modifications depositionand structuring The preparation techniques and methods of

thin film preparation have been significantly enhanced in thepast decade due to better understanding of the physics andchemistry of thin films alongwith their fundamental aspectsmicrostructural evolution and their respective properties

6 Conclusion

The selection of a specific deposition method needs varietyof consideration and criteria such as thin film applicationmaterial characteristics and process technology It is foundthat there is no general guideline for choosing the bestdeposition method However different preparations anddeposition technologies with materialsrsquo and substratesrsquo typespecified application cost and requested efficiency allowthe researchers to select a more appropriate technique fortheir research Future work focuses more on the fabricationconditions and accounts for more parameters in order tocompare the available chemical preparationmethods in termsof their effect onDSSC efficiency stability durability cost andoptimization of the working conditions


Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

The authors would like to thank the UKMDIP-2012-22and DLP-2013-015 Research Funds for providing financialsupport to this study

References

[1] L Wang X Fang and Z Zhang ldquoDesign methods for largescale dye-sensitized solar modules and the progress of stabilityresearchrdquoRenewable and Sustainable EnergyReviews vol 14 no9 pp 3178ndash3184 2010

[2] Y-D Zhang X-M Huang D-M Li Y-H Luo and Q-BMeng ldquoHow to improve the performance of dye-sensitized solarcell modules by light collectionrdquo Solar Energy Materials andSolar Cells vol 98 pp 417ndash423 2012

[3] Y-D Zhang X-M Huang Y-Y Yang et al ldquoHow to improvethe performance of dye-sensitized solar modules by lsquobackleadsrsquordquo Solar Energy Materials and Solar Cells vol 102 pp 109ndash113 2012

[4] Q Zhang and G Cao ldquoNanostructured photoelectrodes fordye-sensitized solar cellsrdquo Nano Today vol 6 no 1 pp 91ndash1092011

[5] J Gong J Liang and K Sumathy ldquoReview on dye-sensitizedsolar cells (DSSCs) fundamental concepts and novel materialsrdquoRenewable and Sustainable Energy Reviews vol 16 no 8 pp5848ndash5860 2012

[6] H C Weerasinghe F Huang and Y-B Cheng ldquoFabricationof flexible dye sensitized solar cells on plastic substratesrdquo NanoEnergy vol 2 no 2 pp 174ndash189 2013

[7] K L Choy ldquoChemical vapour deposition of coatingsrdquo Progressin Materials Science vol 48 no 2 pp 57ndash170 2003

[8] K Seshan Handbook of Thin-Film Deposition Processes andTechniques Principles Methods Equipment and ApplicationsNoyes PublicationsWilliam Andrew Publishing Norwich NYUSA 2nd edition 2002

[9] J L Zilko ldquoMetal organic chemical vapor deposition tech-nology and equipmentrdquo in Handbook of Thin Film DepositionProcesses and Techniques Principles Methods Equipment andApplications K Seshan Ed 2002

[10] H Kim H-B-R Lee andW J Maeng ldquoApplications of atomiclayer deposition to nanofabrication and emerging nanodevicesrdquoThin Solid Films vol 517 no 8 pp 2563ndash2580 2009

[11] H Kim Nanomaterials amp Nanopatterning Yonsei University[12] S M George ldquoAtomic layer deposition an overviewrdquo Chemical

Reviews vol 110 no 1 pp 111ndash131 2010[13] M Ritala and M Leskela ldquoAtomic layer depositionrdquo in Hand-

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[14] C Goh Growth of SiO2

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[15] S Choopun A Tubtimtae T Santhaveesuk S Nilphai EWongrat and N Hongsith ldquoZinc oxide nanostructures forapplications as ethanol sensors and dye-sensitized solar cellsrdquoApplied Surface Science vol 256 no 4 pp 998ndash1002 2009

[16] Y-T Kim J Park and J Choi ldquoSputter-deposited ZnOthin films consisting of nano-networks for binder-free dye-sensitized solar cellsrdquo Current Applied Physics vol 13 no 2 pp381ndash385 2013

[17] F Hossein-Babaei and S Rahbarpour ldquoTitanium and silvercontacts on thermally oxidized titanium chip electrical and gassensing propertiesrdquo Solid-State Electronics vol 56 no 1 pp 185ndash190 2011

[18] C D Lokhande A M More and J L Gunjakar ldquoMicrostruc-ture dependent performance of chemically deposited nanocrys-tallinemetal oxide thin filmsrdquo Journal of Alloys andCompoundsvol 486 no 1-2 pp 570ndash580 2009

[19] M Paunovic andM Schlesinger Fundamentals of Electrochem-ical Deposition Wiley-Interscience Hoboken NJ USA 2006

[20] X-J Wu F Zhu C Mu et al ldquoElectrochemical synthesis andapplications of oriented and hierarchically quasi-1D semicon-ducting nanostructuresrdquo Coordination Chemistry Reviews vol254 no 9-10 pp 1135ndash1150 2010

[21] AM FernandezM E Calixto P J Sebastian S A Gamboa AM Hermann and R N Noufi ldquoElectrodeposited and selenized(CuInSe2) (CIS) thin films for photovoltaic applicationsrdquo SolarEnergy Materials and Solar Cells vol 52 no 3-4 pp 423ndash4311998

[22] G Zou H Li Y Zhang K Xiong and Y Qian ldquoSolvother-malhydrothermal route to semiconductor nanowiresrdquo Nan-otechnology vol 17 no 11 pp S313ndashS320 2006

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chemistryrdquo Angewandte ChemiemdashInternational Edition vol 24no 12 pp 1026ndash1040 1985

[25] K Eda Hydrothermal Synthesis Kobe University 2006[26] S Somiya and R Roy ldquoHydrothermal synthesis of fine oxide

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[27] Y G Guo HydrothermalSolvothermal Synthesis of Nanomate-rials 2010

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2

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[29] Y Zhao X Gu and Y Qiang ldquoInfluence of growth timeand annealing on rutile TiO

2

single-crystal nanorod arrayssynthesized by hydrothermal method in dye-sensitized solarcellsrdquoThin Solid Films vol 520 no 7 pp 2814ndash2818 2012

[30] J-K Oh J-K Lee B Han S-J Kim and K-W Park ldquoTiO2

rutile nanowire electrodes for dye-sensitized solar cellsrdquoMate-rials Letters vol 68 pp 4ndash7 2012

[31] J Jung J Myoung and S Lim ldquoEffects of ZnO nanowiresynthesis parameters on the photovoltaic performance of dye-sensitized solar cellsrdquoThin Solid Films vol 520 no 17 pp 5779ndash5789 2012

[32] Y Kim J H Jeong and M Kang ldquoRapid synthesis of bis(221015840-bipyridine) nitratocopper(II) nitrate using a hydrothermalmethod and its application to dye-sensitized solar cellsrdquo Inor-ganica Chimica Acta vol 365 no 1 pp 400ndash407 2011

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core-shelllong nanowire arrays and their application on dye-sensitizedsolar cellsrdquo Journal of Solid State Chemistry vol 190 pp 303ndash308 2012

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in dye-sensitized solar cellrdquo Solar Energy Materials and SolarCells vol 85 no 3 pp 457ndash465 2005

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2

via sol-gel process for dye-sensitized solar cellsrdquo Microporousand Mesoporous Materials vol 142 no 2-3 pp 473ndash480 2011

[38] W H Sutton ldquoMicrowave processing of ceramic materialsrdquoTheAmerican Ceramic Society Bulletin vol 68 no 2 pp 376ndash3861989

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[40] S G Deng and Y S Lin ldquoMicrowave synthesis of mesoporousand microporous alumina powdersrdquo Journal of Materials Sci-ence Letters vol 16 no 15 pp 1291ndash1294 1997

[41] R Roy D Agrawal J Cheng and S Gedevanishvili ldquoFullsintering of powdered-metal bodies in a microwave fieldrdquoNature vol 399 pp 668ndash670 1999

[42] K J Rao P A Ramakrishnan and R Gadagkar ldquoMicrowavepreparation of oxide bronzesrdquo Journal of Solid State Chemistryvol 148 no 1 pp 100ndash107 1999

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[44] T Yamamoto Y Wada H Yin T Sakata H Mori and SYanagida ldquoMicrowave-driven polyol method for preparation ofTiO2

nanocrystallitesrdquo Chemistry Letters no 10 pp 964ndash9652002

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2

nanocrystalline electrode fordye-sensitized solar cells by 28GHz microwave irradiationrdquoSolar Energy Materials and Solar Cells vol 81 no 1 pp 135ndash1392004

[46] XHu G Li and J C Yu ldquoDesign fabrication andmodificationof nanostructured semiconductor materials for environmentaland energy applicationsrdquo Langmuir vol 26 no 5 pp 3031ndash3039 2010

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2

for enhancedsurface properties finite ostwald ripening by a microwavehydrothermal processrdquo Langmuir vol 22 no 5 pp 2016ndash20272006

[48] P Zhang S Yin and T Sato ldquoSynthesis of high-activityTiO2

photocatalyst via environmentally friendly and novelmicrowave assisted hydrothermal processrdquo Applied Catalysis Bvol 89 no 1-2 pp 118ndash122 2009

[49] J N Hart R Cervini Y B Cheng G P Simon and L SpiccialdquoFormation of anatase TiO

2

by microwave processingrdquo SolarEnergy Materials and Solar Cells vol 84 no 1ndash4 pp 135ndash1432004

[50] I Zumeta J A Ayllon B Gonzalez X Domenech and E VigilldquoTiO2

films obtained by microwave-activated chemical-bath

deposition used to improve TiO2

-conducting glass contactrdquoSolar Energy Materials and Solar Cells vol 93 no 10 pp 1728ndash1732 2009

[51] S Ribbens V Meynen G V Tendeloo et al ldquoDevelopment ofphotocatalytic efficient Ti-based nanotubes and nanoribbonsby conventional and microwave assisted synthesis strategiesrdquoMicroporous and Mesoporous Materials vol 114 no 1ndash3 pp401ndash409 2008

[52] Y Li H Li T Li G Li and R Cao ldquoFacile synthesis ofmesoporous titanium dioxide nanocomposites with control-lable phase compositions by microwave-assisted esterificationrdquoMicroporous andMesoporousMaterials vol 117 no 1-2 pp 444ndash449 2009

[53] P Periyat N Leyland D E McCormack J Colreavy D Corrand S C Pillai ldquoRapid microwave synthesis of mesoporousTiO2

for electrochromic displaysrdquo Journal of Materials Chem-istry vol 20 no 18 pp 3650ndash3655 2010

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[58] K S Suslick S-B Choe A A Cichowlas and M W GrinstaffldquoSonochemical synthesis of amorphous ironrdquo Nature vol 353no 6343 pp 414ndash416 1991

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[62] A Tubtimtae and M W Lee ldquoZnO nanorods on undoped andindium-dopedZnO thin films as a TCO layer on nonconductiveglass for dye-sensitized solar cellsrdquo Superlattices andMicrostruc-tures vol 52 no 5 pp 987ndash996 2012

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[65] Y Wang X Cui Y Zhang X Gao and Y Sun ldquoPreparation ofcauliflower-like ZnO films by chemical bath deposition pho-tovoltaic performance and equivalent circuit of dye-sensitizedsolar cellsrdquo Journal of Materials Science and Technology vol 29no 2 pp 123ndash127 2013


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[67] Y-M Lee and H-W Yang ldquoOptimization of processing param-eters on the controlled growth of ZnO nanorod arrays for theperformance improvement of solid-state dye-sensitized solarcellsrdquo Journal of Solid State Chemistry vol 184 no 3 pp 615ndash623 2011

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[70] E Vigil B Gonzalez I Zumeta et al ldquoThe role of conducting-oxide-substrate type and morphology in TiO

2

films grown bymicrowave chemical bath deposition (MW-CBD) and theirphotovoltaic characteristicsrdquo Journal of Crystal Growth vol 262no 1ndash4 pp 366ndash374 2004

[71] S M Pawar B S Pawar J H Kim O-S Joo and C DLokhande ldquoRecent status of chemical bath deposited metalchalcogenide and metal oxide thin filmsrdquo Current AppliedPhysics vol 11 no 2 pp 117ndash161 2011

[72] C-M Chen C-H Chen and T-C Wei ldquoChemical depositionof platinum on metallic sheets as counterelectrodes for dye-sensitized solar cellsrdquo Electrochimica Acta vol 55 no 5 pp1687ndash1695 2010

[73] J-L Lan Y-YWang C-CWan et al ldquoThe simple and easy wayto manufacture counter electrode for dye-sensitized solar cellsrdquoCurrent Applied Physics vol 10 no 2 pp S168ndashS171 2010

[74] Y Li H Zhang B Guo and M Wei ldquoEnhanced efficiencydye-sensitized SrSnO

3

solar cells prepared using chemical bathdepositionrdquo Electrochimica Acta vol 70 pp 313ndash317 2012

[75] M Ristov G Sinadinovski and I Grozdanov ldquoChemicaldeposition of Cu

2

O thin filmsrdquo Thin Solid Films vol 123 no1 pp 63ndash67 1985

[76] Y F Nicolau ldquoSolution deposition of thin solid compound filmsby a successive ionic-layer adsorption and reaction processrdquoApplied Surface Science vol 22-23 no 2 pp 1061ndash1074 1985

[77] H M Pathan and C D Lokhande ldquoDeposition of metalchalcogenide thin films by successive ionic layer adsorption andreaction (SILAR) methodrdquo Bulletin of Materials Science vol 27no 2 pp 85ndash111 2004

[78] S Das P Sudhagar S Nagarajan et al ldquoSynthesis of graphene-CoS electro-catalytic electrodes for dye sensitized solar cellsrdquoCarbon vol 50 no 13 pp 4815ndash4821 2012

[79] J Chung J Myoung J Oh and S Lim ldquoSuccessive ionic layeradsorption and reaction of ZnSe shells for ZnOnanowire-baseddye-sensitized solar cellsrdquo Journal of Physics and Chemistry ofSolids vol 73 no 4 pp 535ndash539 2012

[80] P S Patil ldquoVersatility of chemical spray pyrolysis techniquerdquoMaterials Chemistry and Physics vol 59 no 3 pp 185ndash198 1999

[81] M Okuya K Nakade D Osa T Nakano G R A Kumara andS Kaneko ldquoFabrication of dye-sensitized solar cells by spraypyrolysis deposition (SPD) techniquerdquo Journal of Photochem-istry and Photobiology A vol 164 no 1ndash3 pp 167ndash172 2004

[82] W-H Yen C C Hsieh H W Wang C Y Hung and M CTsui ldquoFlexible TiO

2

working electrode for dye-sensitized solar

cellsrdquo Journal of the Chinese Chemical Society vol 57 no 5 pp1162ndash1166 2010

[83] MHHabibiMMikhakM Zendehdel andMHabibi ldquoInflu-ence of nanostructured zinc titanate zinc oxide or titaniumdioxide thin film coated on fluorine doped tin oxide as workingelectrodes for dye-sensitized solar cellrdquo International Journal ofElectrochemical Science vol 7 pp 6787ndash6798 2012

[84] A Cannavale F Fiorito M Manca G Tortorici R Cingolaniand G Gigli ldquoMultifunctional bioinspired sol-gel coatings forarchitectural glassesrdquo Building and Environment vol 45 no 5pp 1233ndash1243 2010

[85] J-Y Bae D Lim H-G Yun M Kim J Jin and B-S BaeldquoA quasi-solid-state dye-sensitized solar cell based on sol-gelderived in situ gelation of a siloxane hybrid electrolyterdquo RSCAdvances vol 2 no 13 pp 5524ndash5527 2012

[86] H J Jung ldquoCharacterization of TiO2

nanocrystalline films forhigh performance dye-sensitized solar cellsrdquo Transactions onElectrical and Electronic Materials vol 12 no 3 pp 123ndash1262011

[87] M Boucharef C Di Bin M S Boumaza et al ldquoSolid-state dye-sensitized solar cells based on ZnO nanocrystalsrdquoNanotechnol-ogy vol 21 no 20 Article ID 205203 2010

[88] S Rani P Suri P K Shishodia and R M Mehra ldquoSynthesis ofnanocrystalline ZnOpowder via sol-gel route for dye-sensitizedsolar cellsrdquo Solar EnergyMaterials and Solar Cells vol 92 no 12pp 1639ndash1645 2008

[89] A O T Patrocınio E B Paniago R M Paniago and N Y MIha ldquoXPS characterization of sensitized n-TiO

2

thin films fordye-sensitized solar cell applicationsrdquo Applied Surface Sciencevol 254 no 6 pp 1874ndash1879 2008

[90] J N Hart D Menzies Y-B Cheng G P Simon and L SpiccialdquoTiO2

sol-gel blocking layers for dye-sensitized solar cellsrdquoComptes Rendus Chimie vol 9 no 5-6 pp 622ndash626 2006

[91] W H Jung N-S Kwak T S Hwang and K B Yi ldquoPreparationof highly porous TiO

2

nanofibers for dye-sensitized solar cells(DSSCs) by electro-spinningrdquo Applied Surface Science vol 261pp 343ndash352 2012

[92] Y Chen E Stathatos and D D Dionysiou ldquoSol-gel modifiedTiO2

powder films for high performance dye-sensitized solarcellsrdquo Journal of Photochemistry and Photobiology A vol 203no 2-3 pp 192ndash198 2009

[93] Y-M Lee C-H Hsu and H-W Chen ldquoStructural opticaland electrical properties of p-type NiO films and compositeTiO2

NiO electrodes for solid-state dye-sensitized solar cellsrdquoApplied Surface Science vol 255 no 8 pp 4658ndash4663 2009

[94] Y Zhang Y Shen F Gu M Wu Y Xie and J ZhangldquoInfluence of Fe ions in characteristics and optical properties ofmesoporous titanium oxide thin filmsrdquo Applied Surface Sciencevol 256 no 1 pp 85ndash89 2009

[95] J Sabataityte I Oja F Lenzmann O Volobujeva and MKrunks ldquoCharacterization of nanoporous TiO

2

films preparedby sol-gel methodrdquo Comptes Rendus Chimie vol 9 no 5-6 pp708ndash712 2006

[96] H-M Kwon D-W Han D-J Kwak and Y-M Sung ldquoPrepa-ration of nanoporous F-doped tin dioxide films for TCO-lessdye-sensitized solar cells applicationrdquo Current Applied Physicsvol 10 no 2 pp S172ndashS175 2010

[97] F Bosc P Lacroix-Desmazes and A Ayral ldquoTiO2

anatase-basedmembranes with hierarchical porosity and photocatalyticpropertiesrdquo Journal of Colloid and Interface Science vol 304 no2 pp 545ndash548 2006


[98] OD Velev PM Tessier AM Lenhoff and EWKaler ldquoA classof porous metallic nanostructuresrdquoNature vol 401 no 6753 p548 1999

[99] L J Fu T Zhang Q Cao H P Zhang and Y P Wu ldquoPrepa-ration and characterization of three-dimensionally orderedmesoporous titaniamicroparticles as anodematerial for lithiumion batteryrdquo Electrochemistry Communications vol 9 no 8 pp2140ndash2144 2007

[100] Y Lan X Gao H Zhu et al ldquoTitanate nanotubes and nanorodsprepared from rutile powderrdquo Advanced Functional Materialsvol 15 no 8 pp 1310ndash1318 2005

[101] M Zukalova A Zukal L Kavan M K Nazeeruddin P Liskaand M Gratzel ldquoOrganized mesoporous TiO

2

films exhibitinggreatly enhanced performance in dye-sensitized solar cellsrdquoNano Letters vol 5 no 9 pp 1789ndash1792 2005

[102] J Jiu F Wang M Sakamoto J Takao and M Adachi ldquoPer-formance of dye-sensitized solar cell based on nanocrystalsTiO2

film prepared with mixed template methodrdquo Solar EnergyMaterials and Solar Cells vol 87 no 1ndash4 pp 77ndash86 2005

[103] J E G J Wijnhoven and W L Vos ldquoPreparation of photoniccrystalsmade of air spheres in titaniardquo Science vol 281 no 5378pp 802ndash804 1998

[104] P Jiang J Cizeron J F Bertone and V L Colvin ldquoPreparationof macroporous metal films from colloidal crystalsrdquo Journal ofthe American Chemical Society vol 121 no 34 pp 7957ndash79581999

[105] P Ni B Cheng and D Zhang ldquoInverse opal with an ultravioletphotonic gaprdquo Applied Physics Letters vol 80 no 11 pp 1879ndash1881 2002

[106] B T Holland C F Blanford and A Stein ldquoSynthesis ofmacroporous minerals with highly ordered three-dimensionalarrays of spheroidal voidsrdquo Science vol 281 no 5376 pp 538ndash540 1998

[107] M E Abdelsalam P N Bartlett J J Baumberg and SCoyle ldquoPreparation of arrays of isolated spherical cavities byself-assembly of polystyrene spheres on self-assembled pre-patterned macroporous filmsrdquo Advanced Materials vol 16 no1 pp 90ndash93 2004

[108] Z Zhong Y Yin B Gates andY Xia ldquoPreparation ofmesoscalehollow spheres of TiO

2

and SnO2

by templating against crys-talline arrays of polystyrene beadsrdquo Advanced Materials vol 12no 3 pp 206ndash209 2000

[109] A Richel N P Johnson and D W McComb ldquoObservationof Bragg reflection in photonic crystals synthesized from airspheres in a titania matrixrdquo Applied Physics Letters vol 76 no14 pp 1816ndash1818 2000

[110] Z Zhou andX S Zhao ldquoOpal and inverse opal fabricatedwith aflow-controlled vertical deposition methodrdquo Langmuir vol 21no 10 pp 4717ndash4723 2005

[111] M Zukalova J Prochazka A Zukal J H Yum and LKavan ldquoStructural parameters controlling the performance oforganized mesoporous TiO

2

films in dye sensitized solar cellsrdquoInorganica Chimica Acta vol 361 no 3 pp 656ndash662 2008

[112] C Dionigi P Greco G Ruani M Cavallini F Borgatti andF Biscarini ldquo3D hierarchical porous TiO

2

films from colloidalcomposite fluidic depositionrdquo Chemistry of Materials vol 20no 22 pp 7130ndash7135 2008

[113] Q B Meng C H Fu Y Einaga Z Z Gu A Fujishimaand O Sato ldquoAssembly of highly ordered three-dimensionalporous structure with nanocrystalline TiO

2

semiconductorsrdquoChemistry of Materials vol 14 no 1 pp 83ndash88 2002

[114] R A Doong S M Chang Y C Hung and I L KaoldquoPreparation of highly ordered titanium dioxide porous filmscharacterization and photocatalytic activityrdquo Separation andPurification Technology vol 58 no 1 pp 192ndash199 2007

[115] Z H Liu X S Cheng H Q Yang X L Chai and X X LiuldquoDeformation and energy-absorption characteristics of thin-wall straight beam under central collisionrdquo Journal of JilinUniversity (Engineering and Technology Edition) vol 36 no 1pp 25ndash30 2006

[116] J C Hulteen and R P van Duyne ldquoNanosphere lithography amaterials general fabrication process for periodic particle arraysurfacesrdquo Journal of Vacuum Science and Technology A vol 13no 3 pp 1553ndash1558 1995

[117] R Micheletto H Fukuda and M Ohtsu ldquoA simple method forthe production of a two-dimensional ordered array of smalllatex particlesrdquo Langmuir vol 11 no 9 pp 3333ndash3336 1995

[118] T Ogi L B Modesto-Lopez F Iskandar and K OkuyamaldquoFabrication of a large area monolayer of silica particles ona sapphire substrate by a spin coating methodrdquo Colloids andSurfaces A vol 297 no 1ndash3 pp 71ndash78 2007

[119] Y-H Jhang Y-T Tsai C-H Tsai et al ldquoNanostructuredplatinum counter electrodes by self-assembled nanospheres fordye-sensitized solar cellsrdquoOrganic Electronics vol 13 no 10 pp1865ndash1872 2012

[120] J Yu J Fan and L Zhao ldquoDye-sensitized solar cells based onhollow anatase TiO

2

spheres prepared by self-transformationmethodrdquo Electrochimica Acta vol 55 no 3 pp 597ndash602 2010

[121] LMalfatti P FalcaroHAmenitsch et al ldquoMesostructured self-assembled titania films for photovoltaic applicationsrdquo Microp-orous and Mesoporous Materials vol 88 no 1ndash3 pp 304ndash3112006

[122] C Cheng J Wu Y Xiao et al ldquoPolyvinyl pyrrolidone aidedpreparation of TiO

2

films used in flexible dye-sensitized solarcellsrdquo Electrochimica Acta vol 56 no 21 pp 7256ndash7260 2011

[123] D Gutierrez-Tauste I Zumeta E Vigil M A Hernandez-Fenollosa X Domenech and J A Ayllon ldquoNew low-temperature preparation method of the TiO

2

porous photo-electrode for dye-sensitized solar cells using UV irradiationrdquoJournal of Photochemistry and Photobiology A vol 175 no 2-3pp 165ndash171 2005

[124] M TomoakiMHideki K Toshiaki andH Yukie ldquoOutcome ofnonpenetrating trabeculectomy for glaucomardquo Japanese Journalof Clinical Ophthalmology vol 58 no 2 pp 187ndash191 2004

[125] T Oekermann D Zhang T Yoshida and H Minoura ldquoElec-tron transport and back reaction in nanocrystalline TiO

2

filmsprepared by hydrothermal crystallizationrdquo Journal of PhysicalChemistry B vol 108 no 7 pp 2227ndash2235 2004

[126] T Clark Jr J D Ruiz H Fan C J Brinker B I Swansonand A N Parikh ldquoA new application of UV-ozone treatmentthe preparation of substrate-supportedmesoporous thin filmsrdquoChemistry of Materials vol 12 no 12 pp 3879ndash3884 2000

[127] G Mincuzzi L Vesce A Reale A Di Carlo and T M BrownldquoEfficient sintering of nanocrystalline titaniumdioxide films fordye solar cells via raster scanning laserrdquo Applied Physics Lettersvol 95 no 10 Article ID 103312 2009

[128] S UchidaM Tomiha H Takizawa andM Kawaraya ldquoFlexibledye-sensitized solar cells by 28GHz microwave irradiationrdquoJournal of Photochemistry and Photobiology A vol 164 no 1ndash3 pp 93ndash96 2004


[129] XGan X Li XGao F Zhuge andWYu ldquoZnOnanowireTiO2

nanoparticle photoanodes prepared by the ultrasonic irradia-tion assisted dip-coating methodrdquoThin Solid Films vol 518 no17 pp 4809ndash4812 2010

[130] H Choi H Kim S Hwang W Choi and M Jeon ldquoDye-sensitized solar cells using graphene-based carbon nano com-posite as counter electroderdquo Solar Energy Materials and SolarCells vol 95 no 1 pp 323ndash325 2011

[131] Y J Chen Y S Lo C H Huang Y C Cai and M CHsu ldquoAnode growth of DSSCs by flat-flame chemical vapordeposition methodrdquo Materials Chemistry and Physics vol 120no 1 pp 181ndash186 2010

[132] K E Kim S-R Jang J Park R Vittal and K-J KimldquoEnhancement in the performance of dye-sensitized solar cellscontaining ZnO-covered TiO

2

electrodes prepared by thermalchemical vapor depositionrdquo Solar Energy Materials and SolarCells vol 91 no 4 pp 366ndash370 2007

[133] G-Y Zeng K-S Nian and K-Y Lee ldquoCharacteristics of a dye-sensitized solar cell based on an anode combining ZnO nanos-tructures with vertically aligned carbon nanotubesrdquo Diamondand Related Materials vol 19 no 12 pp 1457ndash1460 2010

[134] J Y Roh Y H Kim and C S Lee ldquoSynthesis of MWNTsusing thermal chemical vapor deposition for the application ofa counter electrode for DSSCsrdquo Current Applied Physics vol 11no 4 pp S69ndashS72 2011

[135] S H Nam J-S Hyun and J-H Boo ldquoSynthesis of TiO2

thinfilms using singlemolecular precursors byMOCVDmethod fordye-sensitized solar cells application and study on film growthmechanismrdquo Materials Research Bulletin vol 47 no 10 pp2717ndash2721 2012

[136] T-T Wang P Raghunath Y-F Lu Y-C Liu C-H Chiouand M C Lin ldquoObservation of Significant enhancement inthe efficiency of a DSSC by InN nanoparticles over TiO

2

-nanoparticle filmsrdquo Chemical Physics Letters vol 510 no 1-3pp 126ndash130 2011

[137] S Nejati and K K S Lau ldquoIntegration of polymer electrolytesin dye sensitized solar cells by initiated chemical vapor deposi-tionrdquoThin Solid Films vol 519 no 14 pp 4551ndash4554 2011

[138] C Quinonez W Vallejo and G Gordillo ldquoStructural opticaland electrochemical properties of TiO

2

thin films grown byAPCVD methodrdquo Applied Surface Science vol 256 no 13 pp4065ndash4071 2010

[139] P S Shinde and C H Bhosale ldquoProperties of chemical vapourdeposited nanocrystalline TiO

2

thin films and their use indye-sensitized solar cellsrdquo Journal of Analytical and AppliedPyrolysis vol 82 no 1 pp 83ndash88 2008

[140] V Ganapathy B Karunagaran and S-W Rhee ldquoImprovedperformance of dye-sensitized solar cells with TiO

2

aluminacore-shell formation using atomic layer depositionrdquo Journal ofPower Sources vol 195 no 15 pp 5138ndash5143 2010

[141] M Shanmugam M F Baroughi and D Galipeau ldquoEffect ofatomic layer deposited ultra thin HfO

2

and Al2

O3

interfaciallayers on the performance of dye sensitized solar cellsrdquo ThinSolid Films vol 518 no 10 pp 2678ndash2682 2010

[142] T-C Tien F-M Pan L-PWang F Y Tsai and C Lin ldquoGrowthmode transition of atomic layer deposited Al

2

O3

on porousTiO2

electrodes of dye-sensitized solar cellsrdquo Thin Solid Filmsvol 520 no 6 pp 1745ndash1750 2012

[143] J Lee K S Hong K Shin and J Y Jho ldquoFabrication ofdye-sensitized solar cells using ordered and vertically orientedTiO2

nanotube arrays with open and closed endsrdquo Journal of

Industrial and Engineering Chemistry vol 18 no 1 pp 19ndash232012

[144] J Du F Bittner D S Hecht et al ldquoA carbon nanotubes-based transparent conductive substrate for flexible ZnO dye-sensitized solar cellsrdquo Thin Solid Films vol 531 pp 391ndash3972013

[145] R Ranjusha P Lekha K R V Subramanian V N Shantikumarand A Balakrishnan ldquoPhotoanode activity of ZnO nanotubebased dye-sensitized solar cellsrdquo Journal of Materials Scienceand Technology vol 27 no 11 pp 961ndash966 2011

[146] X Gan X Li X Gao X He and F Zhuge ldquoDeposition poten-tial dependence of ZnO-eosin Y hybrid thin films preparedby electrochemical deposition and their photoelectrochemicalpropertiesrdquo Materials Chemistry and Physics vol 114 no 2-3pp 920ndash925 2009

[147] J Elias M Parlinska-Wojtan R Erni et al ldquoPassing the limit ofelectrodeposition ldquogas templaterdquo H

2

nanobubbles for growinghighly crystalline nanoporous ZnOrdquo Nano Energy vol 1 no 5pp 742ndash750 2012

[148] T Yoshida M Iwaya H Ando et al ldquoImproved photoelectro-chemical performance of electrodeposited ZnOEosinY hybridthin films by dye re-adsorptionrdquo Chemical Communicationsvol 10 no 4 pp 400ndash401 2004

[149] C Lin H Lin J Li and X Li ldquoElectrodeposition preparationof ZnO nanobelt array films and application to dye-sensitizedsolar cellsrdquo Journal of Alloys and Compounds vol 462 no 1-2pp 175ndash180 2008

[150] H-W Chen C-Y Lin Y-H Lai et al ldquoElectrophoretic deposi-tion of ZnO film and its compression for a plastic based flexibledye-sensitized solar cellrdquo Journal of Power Sources vol 196 no10 pp 4859ndash4864 2011

[151] X Yin X Liu L Wang and B Liu ldquoElectrophoretic depositionof ZnO photoanode for plastic dye-sensitized solar cellsrdquoElectrochemistry Communications vol 12 no 9 pp 1241ndash12442010

[152] Y-TKim J Park S KimDW Park and J Choi ldquoFabrication ofhierarchical ZnO nanostructures for dye-sensitized solar cellsrdquoElectrochimica Acta vol 78 pp 417ndash421 2012

[153] J Qiu M Guo Y Feng and X Wang ldquoElectrochemicaldeposition of branched hierarchical ZnO nanowire arrays andits photoelectrochemical propertiesrdquo Electrochimica Acta vol56 no 16 pp 5776ndash5782 2011

[154] C H Yoon R Vittal J Lee W-S Chae and K-J KimldquoEnhanced performance of a dye-sensitized solar cell with anelectrodeposited-platinum counter electroderdquo ElectrochimicaActa vol 53 no 6 pp 2890ndash2896 2008

[155] G Yue JWu Y Xiao et al ldquoPlatinumgraphene hybrid film as acounter electrode for dye-sensitized solar cellsrdquo ElectrochimicaActa vol 92 pp 64ndash70 2013

[156] G H Guai Q L Song C X Guo et al ldquoGraphene-PtITO counter electrode to significantly reduce Pt loading andenhance charge transfer for high performance dye-sensitizedsolar cellrdquo Solar Energy vol 86 no 7 pp 2041ndash2048 2012

[157] P Li J Wu J Lin M Huang Z Lan and Q Li ldquoImprove-ment of performance of dye-sensitized solar cells based onelectrodeposited-platinum counter electroderdquo ElectrochimicaActa vol 53 no 12 pp 4161ndash4166 2008

[158] C-C Yang H Q Zhang and Y R Zheng ldquoDSSC with a novelPt counter electrodes using pulsed electroplating techniquesrdquoCurrent Applied Physics vol 11 no 1 pp S147ndashS153 2011


[159] X Yin Z Xue and B Liu ldquoElectrophoretic deposition of Ptnanoparticles on plastic substrates as counter electrode forflexible dye-sensitized solar cellsrdquo Journal of Power Sources vol196 no 4 pp 2422ndash2426 2011

[160] C-M Chen C-H Chen S-J Cherng and T-C Wei ldquoElec-troless deposition of platinum on indium tin oxide glass asthe counterelectrode for dye-sensitized solar cellsrdquo MaterialsChemistry and Physics vol 124 no 1 pp 173ndash178 2010

[161] M-H Yeh C-P Lee L-Y Lin et al ldquoA composite poly(33-diethyl-34-dihydro-2H-thieno-[34-b][14]-dioxepine) and Ptfilm as a counter electrode catalyst in dye-sensitized solar cellsrdquoElectrochimica Acta vol 56 no 17 pp 6157ndash6164 2011

[162] T-Y Tsai and S-Y Lu ldquoA novel way of improving lightharvesting in dye-sensitized solar cellsmdashelectrodeposition oftitaniardquo Electrochemistry Communications vol 11 no 11 pp2180ndash2183 2009

[163] Y-L Xie Z-X Li Z-G Xu and H-L Zhang ldquoPreparation ofcoaxial TiO

2

ZnO nanotube arrays for high-efficiency photo-energy conversion applicationsrdquo Electrochemistry Communica-tions vol 13 no 8 pp 788ndash791 2011

[164] S Sakurai H-Q Jiang M Takahashi and K KobayashildquoEnhanced performance of a dye-sensitized solar cell witha modified poly(34-ethylenedioxythiophene)TiO

2

FTOcounter electroderdquo Electrochimica Acta vol 54 no 23 pp5463ndash5469 2009

[165] H-J An S-R Jang R Vittal J Lee and K-J Kim ldquoCationicsurfactant promoted reductive electrodeposition of nanocrys-talline anatase TiO

2

for application to dye-sensitized solar cellsrdquoElectrochimica Acta vol 50 no 13 pp 2713ndash2718 2005

[166] K Wessels M Maekawa J Rathousky and T OekermannldquoOne-step electrodeposition of TiO

2

dye hybrid filmsrdquo ThinSolid Films vol 515 no 16 pp 6497ndash6500 2007

[167] L Zhao J Yu J Fan P Zhai and S Wang ldquoDye-sensitizedsolar cells based on ordered titanate nanotube films fabricatedby electrophoretic deposition methodrdquo Electrochemistry Com-munications vol 11 no 10 pp 2052ndash2055 2009

[168] G-S Kim H-K Seo V P Godble Y-S Kim O B Yang andH-S Shin ldquoElectrophoretic deposition of titanate nanotubesfrom commercial titania nanoparticles application to dye-sensitized solar cellsrdquo Electrochemistry Communications vol 8no 6 pp 961ndash966 2006

[169] H-W Chen K-C Huang C-Y Hsu et al ldquoElectrophoreticdeposition of TiO

2

film on titanium foil for a flexible dye-sensitized solar cellrdquo Electrochimica Acta vol 56 no 23 pp7991ndash7998 2011

[170] H-W Chen C-Y Hsu J-G Chen et al ldquoPlastic dye-sensitizedphoto-supercapacitor using electrophoretic deposition andcompression methodsrdquo Journal of Power Sources vol 195 no18 pp 6225ndash6231 2010

[171] C-C Tsai Y-Y Chu and H Teng ldquoA simple electrophoreticdepositionmethod to prepare TiO

2

-B nanoribbon thin films fordye-sensitized solar cellsrdquo Thin Solid Films vol 519 no 2 pp662ndash665 2010

[172] S Wang J Zhang S Chen et al ldquoConversion enhancementof flexible dye-sensitized solar cells based on TiO

2

nanotubearrays with TiO

2

nanoparticles by electrophoretic depositionrdquoElectrochimica Acta vol 56 no 17 pp 6184ndash6188 2011

[173] M Chigane and T Shinagawa ldquoTitanium dioxide thin filmsprepared by electrolysis from aqueous solution of titanium-lactic acid complex for dye-sensitized solar cellsrdquo Thin SolidFilms vol 520 no 9 pp 3510ndash3514 2012

[174] P-J Chu S-Y Wu K-C Chen J-L He A Yerokhin andA Matthews ldquoNano-structured TiO

2

films by plasma elec-trolytic oxidation combined with chemical and thermal post-treatments of titanium for dye-sensitised solar cell applica-tionsrdquoThin Solid Films vol 519 no 5 pp 1723ndash1728 2010

[175] D Zheng M Lv S Wang W Guo L Sun and C Lin ldquoAcombined TiO

2

structure with nanotubes and nanoparticles forimproving photoconversion efficiency in dye-sensitized solarcellsrdquo Electrochimica Acta vol 83 pp 155ndash159 2012

[176] H Wang H Li J Wang and J Wu ldquoHigh aspect-ratiotransparent highly ordered titanium dioxide nanotube arraysand their performance in dye sensitized solar cellsrdquo MaterialsLetters vol 80 pp 99ndash102 2012

[177] E Tsuji N Hirata Y Aoki and H Habazaki ldquoPreparation ofnon-annealed anatase TiO

2

film on ITO substrate by anodizingin hot phosphateglycerol electrolyte for dye-sensitized solarcellsrdquoMaterials Letters vol 91 pp 39ndash41 2013

[178] L Sun S Zhang X W Sun and X He ldquoEffect of electric fieldstrength on the length of anodized titania nanotube arraysrdquoJournal of Electroanalytical Chemistry vol 637 no 1-2 pp 6ndash12 2009

[179] Q Pang L Leng L Zhao L Zhou C Liang and Y LanldquoDye sensitized solar cells using freestanding TiO

2

nanotubearrays on FTO substrate as photoanoderdquo Materials Chemistryand Physics vol 125 no 3 pp 612ndash616 2011

[180] H Jha P Roy R Hahn I Paramasivam and P Schmuki ldquoFastformation of aligned high-aspect ratio TiO

2

nanotube bundlesthat lead to increased open circuit voltage when used in dyesensitized solar cellsrdquo Electrochemistry Communications vol 13no 3 pp 302ndash305 2011

[181] H Y Hwang A A Prabu D Y Kim and K J Kim ldquoInfluenceof the organic electrolyte and anodization conditions on thepreparation of well-aligned TiO

2

nanotube arrays in dye-sensitized solar cellsrdquo Solar Energy vol 85 no 7 pp 1551ndash15592011

[182] C-H Chen K-C Chen and J-L He ldquoTransparent conductingoxide glass grown with TiO

2

-nanotube array for dye-sensitizedsolar cellrdquo Current Applied Physics vol 10 no 2 pp S176ndashS1792010

[183] S Wang X Wu W Qin and Z Jiang ldquoTiO2

films prepared bymicro-plasma oxidation method for dye-sensitized solar cellrdquoElectrochimica Acta vol 53 no 4 pp 1883ndash1889 2007

[184] T Hino Y Ogawa and N Kuramoto ldquoPreparation of func-tionalized and non-functionalized fullerene thin films on ITOglasses and the application to a counter electrode in a dye-sensitized solar cellrdquo Carbon vol 44 no 5 pp 880ndash887 2006

[185] Z Chen Y Tian S Li H Zheng andWZhang ldquoElectrodeposi-tion of arborous structure nanocrystalline SnO

2

and applicationin flexible dye-sensitized solar cellsrdquo Journal of Alloys andCompounds vol 515 pp 57ndash62 2012

[186] Y Selk T Yoshida and T Oekermann ldquoVariation of themorphology of electrodeposited copper thiocyanate filmsrdquoThinSolid Films vol 516 no 20 pp 7120ndash7124 2008

[187] K-M Lee P-Y Chen C-Y Hsu et al ldquoA high-performancecounter electrode based on poly(34-alkylenedioxythiophene)for dye-sensitized solar cellsrdquo Journal of Power Sources vol 188no 1 pp 313ndash318 2009

[188] K Okada H Matsui T Kawashima T Ezure and N Tanabeldquo100mmtimes 100mm large-sized dye sensitized solar cellsrdquo Jour-nal of Photochemistry and Photobiology A vol 164 no 1ndash3 pp193ndash198 2004


[189] J Chen B Li J Zheng J Zhao H Jing and Z Zhu ldquoPolyani-line nanofibercarbon film as flexible counter electrodes inplatinum-free dye-sensitized solar cellsrdquo Electrochimica Actavol 56 no 12 pp 4624ndash4630 2011

[190] Y Xiao J-Y Lin W-Y Wang S-Y Tai G Yue and J WuldquoEnhanced performance of low-cost dye-sensitized solar cellswith pulse-electropolymerized polyaniline counter electrodesrdquoElectrochimica Acta vol 90 pp 468ndash474 2013

[191] T Kawashima T Ezure K Okada H Matsui K Goto andN Tanabe ldquoFTOITO double-layered transparent conductiveoxide for dye-sensitized solar cellsrdquo Journal of Photochemistryand Photobiology A vol 164 no 1ndash3 pp 199ndash202 2004

[192] K Goto T Kawashima and N Tanabe ldquoHeat-resisting TCOfilms for PV cellsrdquo Solar Energy Materials and Solar Cells vol90 no 18-19 pp 3251ndash3260 2006

[193] S Katusic P Albers R Kern et al ldquoProduction and character-ization of ITO-Pt semiconductor powder containing nanoscalenoble metal particles catalytically active in dye-sensitized solarcellsrdquo Solar Energy Materials and Solar Cells vol 90 no 13 pp1983ndash1999 2006

[194] C Jiang M Y Leung W L Koh and Y Li ldquoInfluences ofdeposition and post-annealing temperatures on properties ofTiO2

blocking layer prepared by spray pyrolysis for solid-statedye-sensitized solar cellsrdquo Thin Solid Films vol 519 no 22 pp7850ndash7854 2011

[195] C Jiang W L Koh M Y Leung W Hong Y Li and J ZhangldquoInfluences of alcoholic solvents on spray pyrolysis depositionof TiO

2

blocking layer films for solid-state dye-sensitized solarcellsrdquo Journal of Solid State Chemistry vol 198 pp 197ndash2022013

[196] M Okuya K Nakade and S Kaneko ldquoPorous TiO2

thin filmssynthesized by a spray pyrolysis deposition (SPD) techniqueand their application to dye-sensitized solar cellsrdquo Solar EnergyMaterials and Solar Cells vol 70 no 4 pp 425ndash435 2002

[197] HMN Bandara RM G Rajapakse KMurakami G R R AKumara andG A Sepalage ldquoDye-sensitized solar cell based onoptically transparent TiO

2

nanocrystalline electrode preparedby atomized spray pyrolysis techniquerdquoElectrochimicaActa vol56 no 25 pp 9159ndash9161 2011

[198] J Xia N Masaki K Jiang and S Yanagida ldquoFabrication andcharacterization of thin Nb

2

O5

blocking layers for ionic liquid-based dye-sensitized solar cellsrdquo Journal of Photochemistry andPhotobiology A vol 188 no 1 pp 120ndash127 2007

[199] B N Pawar G Cai D Ham et al ldquoPreparation of transparentand conducting boron-doped ZnO electrode for its applicationin dye-sensitized solar cellsrdquo Solar Energy Materials and SolarCells vol 93 no 4 pp 524ndash527 2009

[200] V Dutta ldquoSpray deposited ZnO nanostructured layers for dyesensitized solar cellsrdquo Energy Procedia vol 3 pp 58ndash62 2011

[201] N Alexaki T Stergiopoulos A G Kontos et al ldquoMesoporoustitania nanocrystals prepared using hexadecylamine surfactanttemplate crystallization progress monitoring morphologicalcharacterization and application in dye-sensitized solar cellsrdquoMicroporous andMesoporousMaterials vol 124 no 1ndash3 pp 52ndash58 2009

[202] Y Zhang Z Xie and J Wang ldquoPre-curing of supramolecular-templatedmesoporous TiO

2

films for dye-sensitized solar cellsrdquoThin Solid Films vol 518 no 24 pp e34ndashe37 2010

[203] S Ngamsinlapasathian S Pavasupree Y Suzuki and SYoshikawa ldquoDye-sensitized solar cell made of mesoporoustitania by surfactant-assisted templating methodrdquo Solar EnergyMaterials and Solar Cells vol 90 no 18-19 pp 3187ndash3192 2006

[204] K-J Hwang W-G Shim S-H Jung S-J Yoo and J-W LeeldquoAnalysis of adsorption properties of N719 dye molecules onnanoporous TiO

2

surface for dye-sensitized solar cellrdquo AppliedSurface Science vol 256 no 17 pp 5428ndash5433 2010

[205] X P Lin D M Song X Q Gu Y L Zhao and Y H QiangldquoSynthesis of hollow spherical TiO

2

for dye-sensitized solar cellswith enhanced performancerdquo Applied Surface Science vol 263pp 816ndash820 2012

[206] T K Yun S S Park D Kim et al ldquoPore-size effect on photo-voltaic performance of dye-sensitized solar cells composed ofmesoporous anatase-titaniardquo Journal of Power Sources vol 196no 7 pp 3678ndash3682 2011

[207] Y Liu S Wang Z Shan et al ldquoAnatase TiO2

hollow sphereswith small dimension fabricated via a simple preparationmethod for dye-sensitized solar cells with an ionic liquidelectrolyterdquo Electrochimica Acta vol 60 pp 422ndash427 2012

[208] H Li Y Zhou C Lv and M Dang ldquoTemplated synthesisof ordered porous TiO

2

films and their application in dye-sensitized solar cellrdquoMaterials Letters vol 65 no 12 pp 1808ndash1810 2011

[209] C-C Han S-Y Ho Y-P Lin Y-C Lai W-C Liang andY W Chen-Yang ldquoEffect of 120587-120587 stacking of water miscibleionic liquid template with different cation chain length andcontent on morphology of mesoporous TiO

2

prepared via sol-gel method and the applicationsrdquoMicroporous and MesoporousMaterials vol 131 no 1ndash3 pp 217ndash223 2010

[210] L Qi and D P Birnie III ldquoTemplated titania films with meso-and macroporositiesrdquo Materials Letters vol 61 no 11-12 pp2191ndash2194 2007

[211] Y Fu Z Jin Y Ni H Du and TWang ldquoMicrostructure opticaland optoelectrical properties of mesoporous nc-TiO

2

filmsby hydrolysis-limited sol-gel process with different inhibitorsrdquoThin Solid Films vol 517 no 19 pp 5634ndash5640 2009

[212] Z Liu C Liu J Ya and E Lei ldquoControlled synthesis of ZnOand TiO

2

nanotubes by chemical method and their applicationin dye-sensitized solar cellsrdquo Renewable Energy vol 36 no 4pp 1177ndash1181 2011

[213] E Ramasamy and J Lee ldquoFerrocene-derivatized ordered meso-porous carbon as high performance counter electrodes for dye-sensitized solar cellsrdquo Carbon vol 48 no 13 pp 3715ndash37202010

[214] E Ramasamy J Chun and J Lee ldquoSoft-template synthe-sized ordered mesoporous carbon counter electrodes for dye-sensitized solar cellsrdquo Carbon vol 48 no 15 pp 4563ndash45652010

[215] S-H Park H-R Jung B-K Kim and W-J Lee ldquoMWCNTmesoporous carbon nanofibers composites prepared by elec-trospinning and silica template as counter electrodes for dye-sensitized solar cellsrdquo Journal of Photochemistry and Photobiol-ogy A vol 246 pp 45ndash49 2012

[216] S Sumikura S Mori S Shimizu H Usami and E SuzukildquoSyntheses ofNiOnanoporous films using nonionic triblock co-polymer templates and their application to photo-cathodes ofp-type dye-sensitized solar cellsrdquo Journal of Photochemistry andPhotobiology A vol 199 no 1 pp 1ndash7 2008

[217] N Sharifi S Dadgostar N Taghavinia and A Iraji zadldquoFreestanding light scattering hollow silver spheres prepared bya facile sacrificial templating method and their application indye-sensitized solar cellsrdquo Journal of Power Sources vol 225 pp46ndash50 2013

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy


Carbohydrate Chemistry

International Journal of


Journal of

Chemistry


Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of


Chromatography Research International


Applied ChemistryJournal of



Theoretical ChemistryJournal of


Journal of

Spectroscopy

Analytical ChemistryInternational Journal of


Journal of


Quantum Chemistry


Organic Chemistry International

ElectrochemistryInternational Journal of



CatalystsJournal of


2 Gas Phase Precursors

21 Chemical Vapor Deposition (CVD) The process that iscalled chemical vapor deposition (CVD) of films and coatingsis the result of chemical reactions that occur between thegaseous reactant close to or adjacent to the surface of a heatedsubstrate (Figure 1) The flexible nature of CVD makes it oneof the preferredmethods of thin filmdeposition and coatingsThe applications of CVD coated thin films are but not limitedto semiconductors for microelectronics optoelectronicsenergy conversion devices dielectrics for microelectronicsrefractory ceramic materials for hard coatings corrosionprotection oxidation or as diffusion barriers metallic filmsfor microelectronics and for protective coatings and fiberproduction and coating [7]

211 Advantages and Disadvantages of CVD On top of itscomplex chemical system some of the advantages of CVDsare [7] as follows

(a) Being able to produce extremely dense and purematerials and allowing manipulation at the atomic ornanometer scales

(b) The films are highly uniform and have good repro-ducibility and adhesion with acceptable depositionrates

(c) Due to its good throwing power and nonline of sightnature it can be used to uniformly coat complex-shaped components and deposit filmswith reasonableconformal coverage which is significantly advanta-geous compared to the physical vapor deposition(PVD) processes

(d) Properties such as crystal structure surface mor-phology and orientation of the products can bemanipulated and customized via the CVDrsquos processparameters

(e) It is capable of producing a variety of coatings suchas single layer multilayer composite nanostructuredand functionally graded coating materials along withwell-controlled dimension and unique structure atlow processing temperatures

(f) The rate of deposition can be readily adjusted Lowdeposition rates are favored for the growth of epitaxialthin films formicroelectronic applications while highdeposition rates are preferred for the deposition ofthick protective coatings

(g) The processing cost for the conventional CVD tech-nique is quite low

(h) The CVD technique allows the usage of a wide varietyof chemical precursors such as halides hydrides andorganometallics which enables the deposition of alarge spectrum of materials that encompasses metalscarbides nitrides oxides sulphides IIIndashV and IIndashVImaterials

(i) The low deposition temperatures allow the desiredphases to be deposited in-situ at low energies via

Heater

Film

Susceptor Substrate

X2 (g)AX2 (g)

AB2 (s) or (1)

Figure 1 A schematic diagram of the CVD coating [7]

vapor phase reactions or nucleation and growthon the substratersquos surface This in turn allows thedeposition of refractorymaterials at a fraction of theirrespective melting temperatures

However the drawbacks of this technique include the follow-ing

(a) the inherent chemical and safety hazards that mightbe instigated by the use of toxic corrosive flammableandor explosive precursor gases Recently howeverthese issues have been mitigated by using variantsof CVD methods such as electrostatic spray-assistedvapor deposition (ESAVD) and combustion chemicalvapor deposition (CCVD) methods which employmore environmental-friendly precursors

(b) the difficulty encountered when trying to depositmulticomponent materials with well-controlled stoi-chiometry via multisource precursors due to the factthat different precursors adhere to different vaporiza-tion rates However this limitation can be negated viathe utilization of single source chemical precursors

(c) the high level of sophistication in the reactor orvacuum system in CVD variants such as low pressureor ultrahigh vacuumCVD plasma-assistedCVD andphoto-assisted CVD tends will inevitably increase thecost of production However there are exceptionsto this case such as aerosol assisted chemical vapordeposition (AACVD) and flame-assisted chemicalvapor deposition (FACVD) where it might be aviable alternative that guarantees low productioncosts [7]

212 Variants of CVDMethods Both the conventional CVDand thermal activated CVD (TACVD) rely upon thermalenergy to activate chemical reactions However other sourcesof energy are also viable for this purpose The advancementsand uniqueness of different variants of the CVD method arediscussed and detailed by Choy [7] while Figure 2 representsthe relationship between different parameters and coatingproperties

In all of the CVD processes several basic functions mustbe provided This includes free movement of the reactantsanddiluents gases to the deposition surface utilizing differentsource to provide reactantrsquos activation energy and maintain


Process parameters



Coating properties




CVD phenomena

∙ Thermodynamics


phasesurface)

∙ Mass transport

∙ Microstructure
























Precursor

Byproduct

Reactant



1 cycle




















Siliconwafers

Exhaust

Quartz tube

HCl H2N2

O2




















Reference electrode









Spring

Stainless steellid

Teflon liner

Precursorsolution




























119909







Table 3 Continued




0092 [183]










Solidphase

Solidphase

Solidphase


Starting materials

Heating Pressure

Dissolution

Doposition







4
















2nanoparticles



3COO)








cations











Rotor

Precursor solution

Oil filled bath

Magnetic niddal

Heater

StandSubstrate

Thermometer

Thin film






CationsAnions









Exhaustsystem

Nozzle support

Gas flowcontroller

Nozzle

Depositionchamber

Substrates

Iron plate

HeaterThermocouple


Powersupply

Mechanical system

Nozzle shaft

Solution

Solution container









119899




2nanoparticles





Spin coating

Drying

Pre-sintering

Stacking



Spraying

Stacking


(b) SPD technique


Xerogel filmHeat

Heat

Coating

Coating

GellingHydrolysis

polymerisation

Sol

Precipitating

Uniform particles

Wet gel

Dense film

Evaporation


Aerogel


Spinning





2 doped TiO

2 and TiO

2composites










2


2porous films were



































746 [214]







5 Lessons Learned




6 Conclusion





Acknowledgment


References






























2



2














2











2




2





2




























2






3



2









2











2





2








2










2










2

and SnO2





2



2



2









2




2



2




2











2







2




2



2



2



2

and Al2

O3



2

O3

on porousTiO2









2



















2



2



2



2





2




2



2


2




2



2




2




2



2



2



2






2














2





2



2

O5






2




2



2






2



2




2



2
















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


Process parameters



Coating properties




CVD phenomena

∙ Thermodynamics


phasesurface)

∙ Mass transport

∙ Microstructure
























Precursor

Byproduct

Reactant



1 cycle




















Siliconwafers

Exhaust

Quartz tube

HCl H2N2

O2




















Reference electrode









Spring

Stainless steellid

Teflon liner

Precursorsolution




























119909







Table 3 Continued




0092 [183]










Solidphase

Solidphase

Solidphase


Starting materials

Heating Pressure

Dissolution

Doposition







4
















2nanoparticles



3COO)








cations











Rotor

Precursor solution

Oil filled bath

Magnetic niddal

Heater

StandSubstrate

Thermometer

Thin film






CationsAnions









Exhaustsystem

Nozzle support

Gas flowcontroller

Nozzle

Depositionchamber

Substrates

Iron plate

HeaterThermocouple


Powersupply

Mechanical system

Nozzle shaft

Solution

Solution container









119899




2nanoparticles





Spin coating

Drying

Pre-sintering

Stacking



Spraying

Stacking


(b) SPD technique


Xerogel filmHeat

Heat

Coating

Coating

GellingHydrolysis

polymerisation

Sol

Precipitating

Uniform particles

Wet gel

Dense film

Evaporation


Aerogel


Spinning





2 doped TiO

2 and TiO

2composites










2


2porous films were



































746 [214]







5 Lessons Learned




6 Conclusion





Acknowledgment


References






























2



2














2











2




2





2




























2






3



2









2











2





2








2










2










2

and SnO2





2



2



2









2




2



2




2











2







2




2



2



2



2

and Al2

O3



2

O3

on porousTiO2









2



















2



2



2



2





2




2



2


2




2



2




2




2



2



2



2






2














2





2



2

O5






2




2



2






2



2




2



2
















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of
















Precursor

Byproduct

Reactant



1 cycle




















Siliconwafers

Exhaust

Quartz tube

HCl H2N2

O2




















Reference electrode









Spring

Stainless steellid

Teflon liner

Precursorsolution




























119909







Table 3 Continued




0092 [183]










Solidphase

Solidphase

Solidphase


Starting materials

Heating Pressure

Dissolution

Doposition







4
















2nanoparticles



3COO)








cations











Rotor

Precursor solution

Oil filled bath

Magnetic niddal

Heater

StandSubstrate

Thermometer

Thin film






CationsAnions









Exhaustsystem

Nozzle support

Gas flowcontroller

Nozzle

Depositionchamber

Substrates

Iron plate

HeaterThermocouple


Powersupply

Mechanical system

Nozzle shaft

Solution

Solution container









119899




2nanoparticles





Spin coating

Drying

Pre-sintering

Stacking



Spraying

Stacking


(b) SPD technique


Xerogel filmHeat

Heat

Coating

Coating

GellingHydrolysis

polymerisation

Sol

Precipitating

Uniform particles

Wet gel

Dense film

Evaporation


Aerogel


Spinning





2 doped TiO

2 and TiO

2composites










2


2porous films were



































746 [214]







5 Lessons Learned




6 Conclusion





Acknowledgment


References






























2



2














2











2




2





2




























2






3



2









2











2





2








2










2










2

and SnO2





2



2



2









2




2



2




2











2







2




2



2



2



2

and Al2

O3



2

O3

on porousTiO2









2



















2



2



2



2





2




2



2


2




2



2




2




2



2



2



2






2














2





2



2

O5






2




2



2






2



2




2



2
















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of










Siliconwafers

Exhaust

Quartz tube

HCl H2N2

O2




















Reference electrode









Spring

Stainless steellid

Teflon liner

Precursorsolution




























119909







Table 3 Continued




0092 [183]










Solidphase

Solidphase

Solidphase


Starting materials

Heating Pressure

Dissolution

Doposition







4
















2nanoparticles



3COO)








cations











Rotor

Precursor solution

Oil filled bath

Magnetic niddal

Heater

StandSubstrate

Thermometer

Thin film






CationsAnions









Exhaustsystem

Nozzle support

Gas flowcontroller

Nozzle

Depositionchamber

Substrates

Iron plate

HeaterThermocouple


Powersupply

Mechanical system

Nozzle shaft

Solution

Solution container









119899




2nanoparticles





Spin coating

Drying

Pre-sintering

Stacking



Spraying

Stacking


(b) SPD technique


Xerogel filmHeat

Heat

Coating

Coating

GellingHydrolysis

polymerisation

Sol

Precipitating

Uniform particles

Wet gel

Dense film

Evaporation


Aerogel


Spinning





2 doped TiO

2 and TiO

2composites










2


2porous films were



































746 [214]







5 Lessons Learned




6 Conclusion





Acknowledgment


References






























2



2














2











2




2





2




























2






3



2









2











2





2








2










2










2

and SnO2





2



2



2









2




2



2




2











2







2




2



2



2



2

and Al2

O3



2

O3

on porousTiO2









2



















2



2



2



2





2




2



2


2




2



2




2




2



2



2



2






2














2





2



2

O5






2




2



2






2



2




2



2
















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of



Reference electrode









Spring

Stainless steellid

Teflon liner

Precursorsolution




























119909







Table 3 Continued




0092 [183]










Solidphase

Solidphase

Solidphase


Starting materials

Heating Pressure

Dissolution

Doposition







4
















2nanoparticles



3COO)








cations











Rotor

Precursor solution

Oil filled bath

Magnetic niddal

Heater

StandSubstrate

Thermometer

Thin film






CationsAnions









Exhaustsystem

Nozzle support

Gas flowcontroller

Nozzle

Depositionchamber

Substrates

Iron plate

HeaterThermocouple


Powersupply

Mechanical system

Nozzle shaft

Solution

Solution container









119899




2nanoparticles





Spin coating

Drying

Pre-sintering

Stacking



Spraying

Stacking


(b) SPD technique


Xerogel filmHeat

Heat

Coating

Coating

GellingHydrolysis

polymerisation

Sol

Precipitating

Uniform particles

Wet gel

Dense film

Evaporation


Aerogel


Spinning





2 doped TiO

2 and TiO

2composites










2


2porous films were



































746 [214]







5 Lessons Learned




6 Conclusion





Acknowledgment


References






























2



2














2











2




2





2




























2






3



2









2











2





2








2










2










2

and SnO2





2



2



2









2




2



2




2











2







2




2



2



2



2

and Al2

O3



2

O3

on porousTiO2









2



















2



2



2



2





2




2



2


2




2



2




2




2



2



2



2






2














2





2



2

O5






2




2



2






2



2




2



2
















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of















119909







Table 3 Continued




0092 [183]










Solidphase

Solidphase

Solidphase


Starting materials

Heating Pressure

Dissolution

Doposition







4
















2nanoparticles



3COO)








cations











Rotor

Precursor solution

Oil filled bath

Magnetic niddal

Heater

StandSubstrate

Thermometer

Thin film






CationsAnions









Exhaustsystem

Nozzle support

Gas flowcontroller

Nozzle

Depositionchamber

Substrates

Iron plate

HeaterThermocouple


Powersupply

Mechanical system

Nozzle shaft

Solution

Solution container









119899




2nanoparticles





Spin coating

Drying

Pre-sintering

Stacking



Spraying

Stacking


(b) SPD technique


Xerogel filmHeat

Heat

Coating

Coating

GellingHydrolysis

polymerisation

Sol

Precipitating

Uniform particles

Wet gel

Dense film

Evaporation


Aerogel


Spinning





2 doped TiO

2 and TiO

2composites










2


2porous films were



































746 [214]







5 Lessons Learned




6 Conclusion





Acknowledgment


References






























2



2














2











2




2





2




























2






3



2









2











2





2








2










2










2

and SnO2





2



2



2









2




2



2




2











2







2




2



2



2



2

and Al2

O3



2

O3

on porousTiO2









2



















2



2



2



2





2




2



2


2




2



2




2




2



2



2



2






2














2





2



2

O5






2




2



2






2



2




2



2
















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


Table 3 Continued




0092 [183]










Solidphase

Solidphase

Solidphase


Starting materials

Heating Pressure

Dissolution

Doposition







4
















2nanoparticles



3COO)








cations











Rotor

Precursor solution

Oil filled bath

Magnetic niddal

Heater

StandSubstrate

Thermometer

Thin film






CationsAnions









Exhaustsystem

Nozzle support

Gas flowcontroller

Nozzle

Depositionchamber

Substrates

Iron plate

HeaterThermocouple


Powersupply

Mechanical system

Nozzle shaft

Solution

Solution container









119899




2nanoparticles





Spin coating

Drying

Pre-sintering

Stacking



Spraying

Stacking


(b) SPD technique


Xerogel filmHeat

Heat

Coating

Coating

GellingHydrolysis

polymerisation

Sol

Precipitating

Uniform particles

Wet gel

Dense film

Evaporation


Aerogel


Spinning





2 doped TiO

2 and TiO

2composites










2


2porous films were



































746 [214]







5 Lessons Learned




6 Conclusion





Acknowledgment


References






























2



2














2











2




2





2




























2






3



2









2











2





2








2










2










2

and SnO2





2



2



2









2




2



2




2











2







2




2



2



2



2

and Al2

O3



2

O3

on porousTiO2









2



















2



2



2



2





2




2



2


2




2



2




2




2



2



2



2






2














2





2



2

O5






2




2



2






2



2




2



2
















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of





2nanoparticles



3COO)








cations











Rotor

Precursor solution

Oil filled bath

Magnetic niddal

Heater

StandSubstrate

Thermometer

Thin film






CationsAnions









Exhaustsystem

Nozzle support

Gas flowcontroller

Nozzle

Depositionchamber

Substrates

Iron plate

HeaterThermocouple


Powersupply

Mechanical system

Nozzle shaft

Solution

Solution container









119899




2nanoparticles





Spin coating

Drying

Pre-sintering

Stacking



Spraying

Stacking


(b) SPD technique


Xerogel filmHeat

Heat

Coating

Coating

GellingHydrolysis

polymerisation

Sol

Precipitating

Uniform particles

Wet gel

Dense film

Evaporation


Aerogel


Spinning





2 doped TiO

2 and TiO

2composites










2


2porous films were



































746 [214]







5 Lessons Learned




6 Conclusion





Acknowledgment


References






























2



2














2











2




2





2




























2






3



2









2











2





2








2










2










2

and SnO2





2



2



2









2




2



2




2











2







2




2



2



2



2

and Al2

O3



2

O3

on porousTiO2









2



















2



2



2



2





2




2



2


2




2



2




2




2



2



2



2






2














2





2



2

O5






2




2



2






2



2




2



2
















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


Rotor

Precursor solution

Oil filled bath

Magnetic niddal

Heater

StandSubstrate

Thermometer

Thin film






CationsAnions









Exhaustsystem

Nozzle support

Gas flowcontroller

Nozzle

Depositionchamber

Substrates

Iron plate

HeaterThermocouple


Powersupply

Mechanical system

Nozzle shaft

Solution

Solution container









119899




2nanoparticles





Spin coating

Drying

Pre-sintering

Stacking



Spraying

Stacking


(b) SPD technique


Xerogel filmHeat

Heat

Coating

Coating

GellingHydrolysis

polymerisation

Sol

Precipitating

Uniform particles

Wet gel

Dense film

Evaporation


Aerogel


Spinning





2 doped TiO

2 and TiO

2composites










2


2porous films were



































746 [214]







5 Lessons Learned




6 Conclusion





Acknowledgment


References






























2



2














2











2




2





2




























2






3



2









2











2





2








2










2










2

and SnO2





2



2



2









2




2



2




2











2







2




2



2



2



2

and Al2

O3



2

O3

on porousTiO2









2



















2



2



2



2





2




2



2


2




2



2




2




2



2



2



2






2














2





2



2

O5






2




2



2






2



2




2



2
















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


Exhaustsystem

Nozzle support

Gas flowcontroller

Nozzle

Depositionchamber

Substrates

Iron plate

HeaterThermocouple


Powersupply

Mechanical system

Nozzle shaft

Solution

Solution container









119899




2nanoparticles





Spin coating

Drying

Pre-sintering

Stacking



Spraying

Stacking


(b) SPD technique


Xerogel filmHeat

Heat

Coating

Coating

GellingHydrolysis

polymerisation

Sol

Precipitating

Uniform particles

Wet gel

Dense film

Evaporation


Aerogel


Spinning





2 doped TiO

2 and TiO

2composites










2


2porous films were



































746 [214]







5 Lessons Learned




6 Conclusion





Acknowledgment


References






























2



2














2











2




2





2




























2






3



2









2











2





2








2










2










2

and SnO2





2



2



2









2




2



2




2











2







2




2



2



2



2

and Al2

O3



2

O3

on porousTiO2









2



















2



2



2



2





2




2



2


2




2



2




2




2



2



2



2






2














2





2



2

O5






2




2



2






2



2




2



2
















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


Spin coating

Drying

Pre-sintering

Stacking



Spraying

Stacking


(b) SPD technique


Xerogel filmHeat

Heat

Coating

Coating

GellingHydrolysis

polymerisation

Sol

Precipitating

Uniform particles

Wet gel

Dense film

Evaporation


Aerogel


Spinning





2 doped TiO

2 and TiO

2composites










2


2porous films were



































746 [214]







5 Lessons Learned




6 Conclusion





Acknowledgment


References






























2



2














2











2




2





2




























2






3



2









2











2





2








2










2










2

and SnO2





2



2



2









2




2



2




2











2







2




2



2



2



2

and Al2

O3



2

O3

on porousTiO2









2



















2



2



2



2





2




2



2


2




2



2




2




2



2



2



2






2














2





2



2

O5






2




2



2






2



2




2



2
















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of



2 doped TiO

2 and TiO

2composites










2


2porous films were



































746 [214]







5 Lessons Learned




6 Conclusion





Acknowledgment


References






























2



2














2











2




2





2




























2






3



2









2











2





2








2










2










2

and SnO2





2



2



2









2




2



2




2











2







2




2



2



2



2

and Al2

O3



2

O3

on porousTiO2









2



















2



2



2



2





2




2



2


2




2



2




2




2



2



2



2






2














2





2



2

O5






2




2



2






2



2




2



2
















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




















746 [214]







5 Lessons Learned




6 Conclusion





Acknowledgment


References






























2



2














2











2




2





2




























2






3



2









2











2





2








2










2










2

and SnO2





2



2



2









2




2



2




2











2







2




2



2



2



2

and Al2

O3



2

O3

on porousTiO2









2



















2



2



2



2





2




2



2


2




2



2




2




2



2



2



2






2














2





2



2

O5






2




2



2






2



2




2



2
















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




Acknowledgment


References






























2



2














2











2




2





2




























2






3



2









2











2





2








2










2










2

and SnO2





2



2



2









2




2



2




2











2







2




2



2



2



2

and Al2

O3



2

O3

on porousTiO2









2



















2



2



2



2





2




2



2


2




2



2




2




2



2



2



2






2














2





2



2

O5






2




2



2






2



2




2



2
















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of






2











2




2





2




























2






3



2









2











2





2








2










2










2

and SnO2





2



2



2









2




2



2




2











2







2




2



2



2



2

and Al2

O3



2

O3

on porousTiO2









2



















2



2



2



2





2




2



2


2




2



2




2




2



2



2



2






2














2





2



2

O5






2




2



2






2



2




2



2
















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of







2






3



2









2











2





2








2










2










2

and SnO2





2



2



2









2




2



2




2











2







2




2



2



2



2

and Al2

O3



2

O3

on porousTiO2









2



















2



2



2



2





2




2



2


2




2



2




2




2



2



2



2






2














2





2



2

O5






2




2



2






2



2




2



2
















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of






2










2

and SnO2





2



2



2









2




2



2




2











2







2




2



2



2



2

and Al2

O3



2

O3

on porousTiO2









2



















2



2



2



2





2




2



2


2




2



2




2




2



2



2



2






2














2





2



2

O5






2




2



2






2



2




2



2
















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of







2







2




2



2



2



2

and Al2

O3



2

O3

on porousTiO2









2



















2



2



2



2





2




2



2


2




2



2




2




2



2



2



2






2














2





2



2

O5






2




2



2






2



2




2



2
















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of







2



2



2



2





2




2



2


2




2



2




2




2



2



2



2






2














2





2



2

O5






2




2



2






2



2




2



2
















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of










2





2



2

O5






2




2



2






2



2




2



2
















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of










Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

Review Article Research and Development Aspects on Chemical … · 2019. 7. 31. · Review Article Research and Development Aspects on Chemical Preparation Techniques of Photoanodes

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