Master’s Thesis Presentation - Uni Kassel · Master’s Thesis Presentation 13, July, 2016. Comparison Of Novel And State Of The Art Solar Cells Author: Adegbenro Ayodeji REMENA

Master’sThesisPresentation

13,July,2016

ComparisonOfNovelAndStateOfTheArtSolarCells

Author:AdegbenroAyodejiREMENABatch8- 33356695

Supervisors:Prof.Dr.NadiaH.RafatProf.Dr.HartmutHillmer

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AbbreviationØc-Si– CrystallineSilicon

Øa-Si:H– HydrogenatedAmorphousSilicon

ØCdTe– CadmiumTelluride

ØCIGS– CopperIndiumGalliumSelenide

ØDSSC– DyeSensitizeSolarCells

ØGaAs– GalliumArsenide

ØHIT– HeterojunctionIntrinsicThinlayer

ØEPBT– Energypaybacktime

ØGHG– Greenhousegases2

OUTLINE

ØObjectiveofresearch

ØCurrentstatusofevaluatedPVcells

ØSimulationofHITsolarcell

ØWeighingfactors

ØFutureprospectsofHITsolarcell

ØSummaryandConclusion

ØBibliography 3

Objectiveofresearch

• Theobjectiveofthisresearchworkistocompareandshowthe

possibilityofhetero-junctionintrinsicthinlayer(HIT)solarcells

overcomingc-SisolarcellsinthePVindustrybasedonitslow

thermalbudget,higherconversionefficiency(viaPC1D)and

possibilityofthinnersiliconlayers.

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OUTLINE




ØWeighingfactors


ØSummaryandConclusion

ØBibliography 5

Crystallinesiliconsolarcells:- monocrystalline&polycrystalline

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+93%shareofPVmarketasat2015

+Cellandmoduleefficiencyrangesbetween20-25%and12-19%respectively

+Evidenceofdurabilityandlongevityintoughoutdoorconditions

+Productionscale59GWp[2]- Highlevelofembodiedenergyinproduction

- Complexandintricatetofabricatehttp://www.123rf.com/photo_27734440_polycrystalline-solar-cell-3x6-for-diy-solar-panel-isolated-on-white-background.html

Thin filmsolarcells:- a-Si:H,CdTe,CIGS

+Promisinglowcostsolarcells

+Absorptioncoefficientmuchhigherthanc-Sisolarcells

+Easierprocessingstep

+Productionscale>4.2GWp(aSi-1.1Wp,CdTe-2.5Wp,CIGS-0.6Wp)[2]

+Possibilityofdoublejunctionstructure

- Cellefficienciesranging(9-15%)andmuchloweratmodulelevel

- PronetoStaebler-Wronskieffect 7http://materia.nl/article/innovation-thin-film-solar-cells-at-mx2016/, http://www.asmac.com.hk/thin-film-solar-cell.php

GaAs Multi-junction

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+Utilizeshort,mediumandlongwavelengthofthelightspectrum

- Expensivematerialsandintricateprocessingsteps

+Solarcellefficiencyover30%(concentratorandnonconcentrator)

+Excellentforhightemperatureapplications

+Possibilityofdifferentjunctionformation

+Spaceapplicationsandconcentratorsolarcellsapplicationshttp://www.intechopen.com/books/optoelectronics-advanced-materials-and-devices/iii-v-multi-junction-solar-cells &FraunhoferISE

Organicsolarcell:- DSSC&Organicsolarcells

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- Instabilityandlimitationofmaximumtemperature

- Currentefficiencyisstillrelativelylowcomparewithtraditionalsolarcells

+Theylow-costmaterialsandarelessintricatetofabricate

+Perfectfor"lowdensity"applications

+Shortpaybackperiodandlowenvironmentalimpactinfabricationandoperation

+Flexibilityindesigningandstructurehttp://www.infinitypv.com/infinitypro/opv/demonstrator

HeterojunctionIntrinsicThinlayersolarcells

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• A p-type a-Si layer is deposited on a n-type c-Si wafer to form a p/n heterojunction, with an intrinsic a-Si layer in between

• On the other side of the n-type c-Si is an intrinsic and n-type a-Si layers to obtain a Back Surface Field (BSF)

• Lights is absorbed by the c-Si and photo-generated carries are diffused to the a-Si layer for collection

• Combinationofdifferent layersleads tobanddiscontinuities, resulting incarriersblocking layersatbothendsoftheinterface

• Transportofcarriersattheinterfaceisviathermionic emissionandtunneling

• Abandoffsetof0.6eVbetweena-Si:H/c-Siisfavorable

• Differenceinbandgapresultsinablocking layerfortheminoritycarriers


[Seeref3] 11

+ Good stability under thermal and radiation exposure

+ Efficiency capable of exceedingc-Si (>20%)

+ Low thermal budget

+ Cheap intrinsicamorphous Si used as passivator

+ Back surface field reduces rear surface recombination

- Low production scale but high potential to exceed c-Si in future

+ Fabricating temperature about 200ºC

+MinimizedthicknessPtypea-Si:Htoreducetheabsorption

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SANYOElectricCo.,Ltd.

OUTLINE




ØWeighingfactors


ØConclusion

ØBibliography 13

SimulationparametersPC1D- PersonalComputerOneDimensional,isanumericalsimulatingsoftwareforsolarcellsdevelopedin

AustraliaattheuniversitySouthWalesofSydney.Allparameterstakenfromref[4][5]

• Devicecellarea–100cm2

• Lightsource- Onesun(AM1.5,1000W/m2)

• Frontsurface– Textured

• Exteriorfrontreflectance3%[default]

• Exteriorrearreflectance95%[default]

• Ambient temperature at 300K

• Emitter Contact Enabled

• BaseContact0.0015Ω

• Internalconductor0.3S14

SimulationparametersParameter a-Si(p) a-Si(i) c-Si(n) a-Si(n+)

Thickness(μm) 0.01 0.01 300 0.01Dielectricconstant 11.9 11.9 11.9 11.9Electronaffinity(eV) 3.9 3.9 4.05 3.9

Bandgap(eV) 1.72 1.72 1.12 1.72Electronmobility(cm2V-1s-1) 7 7 1140 7

Holemobility(cm2V-1s-1) 1 1 420 1

DopingConcentration(cm-3) 5x1019 0 1.5x1016 8.2x1019

BulkRecombination(μs) 10 0 10 10

Front-SurfaceRecombination(cm/s) 107 107 107 107

Rear-SurfaceRecombination(cm/s) 107 107 107 107

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SimulationResults

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Voc=0.7086V,Isc=3.912A,Pmax=2.333W,FF=84%, ! =23%SchematicofsimulatedcellusingPC1D

SimulationResults

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Effectofa-Si:H(i)asapassivator• Variedfrom2nm-20nm

• Efficiencydecreasesasthicknessdecreases

• Thinnerlayerofa-Si:H(i)isseentobe

effective

• Efficiencyatthickness15nmissamewhen

thecellhasnobufferlayer

• Reductionincostofcellfabrication

• suppressingrateofdegradationofminority

carriers

EffectofBackSurfaceFieldThickness• Backsurfacefieldofasolarcellreduceseffectofrear

surfacerecombinationofchargecarriesonvoltageandcurrent

• TheBSFthicknesswasvariedfrom2-12nmandthereafteritisseenthatthevariationofthickdoesn't’taffecttheoutputoftheHITcell

• Thinnerlayersofn-typea-Si:HisonlyrequiredforHITsolarcell

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SimulationResults

Thickness[nm] Voc[V]

Current[A/cm²]

Efficiency

[%]

2 0.7086 3.911 23.26

4 0.7086 3.912 23.26

8 0.7086 3.9120 23.29

10 0.7086 3.9120 23.33

12 0.7086 3.912 23.33

Cellperformanceasafunctionofthedopingconcentrationofthen-typeamorphouslayer(BSF)

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SimulationResults

Efficiency,opencircuitvoltageandshortcircuitcurrentstartedtosmoothout8.2x1019cm3

and8.2x1020 cm3

Impactofwaferc-Sithickness

• Efficiencyisstablefrom150micrometerbut

thinnerwafercouldbepronetomechanicaland

thermalstress

• Lowabsorptioncoefficientc-Sirequiresincreasein

thickness(~200μm)formorephotocurrent

generation

• Furtherincreaseofc-Sithicknessbeyond200

micrometremightnotbenecessaryandcostcould

besaved20

SimulationResults

OUTLINE




ØWeighingfactors


ØConclusion

ØBibliography 21

Modulecostofproduction• HITsolarcellshavethepossibilityofagoodlearning

curveinthefuture(costandproductionscale)

• c-Sisolarcellsarestillexpensiveduetotheirproductionprocesses

• CIGSandCdTesolarcellsarecheaper,possibilityofhigherproductionscalebuttheyhavelowerefficiencyandalsolimitedinresource

• a-SisolarhaveahugefuturisticproductionscaleandpossibilityoflowercostperwattbutstillpronetoStaebler-Wronskieffect 22

Technology c-Si a-Si:H HIT CIGS CdTe

Cost(€/Wattpeak) 0.88-1.8 0.50-1.2 N/a ca.1.0 ca1.0

Efficiency(%)

13-19 8-11% >19.7 10-12 6-10

Basicmaterialshortage

No No No Indium Tellurium

Productionscale(MWp)

>1000 >500 900 <10 10

Life span (yr) 25 20 20-25 20 20

Thickness(µm) 150-500 100 200 1-2 10

Paybackperiod(yr) 2-4* <1 <1 n/a n/a

Lifecycle&Energyanalysisofc-Si,a-SiandHITPV• c-Si- High temperatureinproduction resultsinhugeproduction energy,moreGHGemissionandhighEPBT.Lowtemperaturecoefficientresulting tolesspowergenerationathigh temperature

• HIT- Lowtemperaturerequired inproduction processthereforelowenergyinproduction, resulting inlowEPBTandlowGHGemission.Hightemperaturestabilityaccompaniedbymorepowergeneration

• a-Si- Lowenergyinproduction, unstableunderhightemperature,lowGHGinproductionbut lowefficiencyresultsinlowpowergeneration

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PVTechnology

EnergyRequired(MJ/m2)

Energypaybackperiod(years)

GHGemission(gCO2eq./k

Wh)

Moduleconversionefficiency

(%)

Crystalline PV 5300-16,500 2-4 63 18

Thin films PV 2500 <1 34.3 11

HITPV N/A <2 N/A 19.7

AnalysisofEfficiencyforevaluatedcells

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c-Sicells-21.3- 25%HITcell-25.6%Thinfilms– 22.1-22.3%

http://www.nrel.gov/ncpv/(NationalRenewable EnergyLaboratory, Golden, CO.)

EnvironmentalIssue

• AllPVtechnologyemitGHGsandpollutantsduringfabrication

• Workersareexposedtohazardouscompoundsduringfabrication

• HITproductionprocessisn'tintricateandcomplex,thereforeworkersareexposedtolessertoxicsubstance

• HITis“greener”thancrystallinesiliconsolarcells

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PV technology Types of Potential Hazards

c-Si SiH4 fires/explosions,silicondust.Acidburns.

a-Si:H SiH4 fires/explosions,ClH3Si,FlammableH2

CdTe Cadmiumandtelluridetoxicity,carcinogenicitychemicalcompounds.

CIGS Cadmiumandseleniumtoxicity,carcinogenicitychemicalcompounds.

GaAs AsH3 toxicity,,carcinogenicitychemicalcompounds,Phosphine.

HIT SiH4 fires/explosions,silicondust,Acidburns,FlammableH2

OUTLINE




ØWeighingfactors


ØConclusion

ØBibliography 26

FutureprospectsofHITsolarcell

• Withhighconversionefficiency,25yearslifetimeandnomaterial

shortage,HITcouldhaveexceedc-Sionmassproductionscale

• Less-expensiveandbetter-performingPVtechnologylikeHITcould

reducethelevelizedcostofelectricityofsolarenergyatarapidrate

• Betterqualitya-Si:Handc-Siresultingtohigherefficiency(>25%)

• HigherPVmarketshare(>c-Si)27

Conclusion• An-typec-Siabsorberwithp-typea-Si:Hemitter,n+-typeBSFandintrinsica-Si:Hinbetweenthelayers,couldpossiblyresulttoahighefficiencyHITsolarcell.

• HITsolarcellcouldbefabricatedatlowertemperature(~200℃)andshorterprocessingtime,unlikec-Sisolarcells.

• Withlowthermalbudget,EPBTisreduced

• Goodthermalstability,accompaniedwithhigherpowergeneration

• PossibilityofreducingofBSFthickness(ca.2-4nm)

• Efficiencyisrelatedtothea-Si:Hlayerthickness,thickerintrinsica-Si:Hlayersleadtoreductioninefficiency

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Bibliograph1. Dr. Alan Doolittle. ECE 4813: Semiconductor Device and Material

Characterization. School of Electrical and Computer Engineering GeorgiaInstitute of Technology.

2. Photovoltaics report ( June, 2016). Fraunhofer Institute for Solar Energy Systems,ISE with support of PSE AG. Pg 40. Freiburg Germany.

3. Yiming Liu, Yun Sun, Wei Liu and Jianghong Yao. (2014). Novel high-efficiencycrystalline-silicon-based compound heterojunction solar cells: HCT(heterojunction with compound thin-layer). Phys. Chem. Chem. Phys.,16, 15400-15410.

4. Manikandan .M, et al. (2015). Performance Analysis on Conversion Efficiency ofHeterojunction with Intrinsic Thin layer (HIT) Solar Cell by PC1D Simulation.Department of ECE, SRM University, Kattankulathur-603203, Tamilnadu, India.

5. NeerajDwivedi,etal.(2012).SimulationapproachforoptimizationofdevicestructureandthicknessofHITsolarcellstoachieve27%efficiency.CSIR–NetworkofInstitutesforSolarEnergy,CSIR– NationalPhysicalLaboratory,Dr.K.S.KrishnanRoad,NewDelhi110012,India. 29

Thankyouforyourtime

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Master’s Thesis Presentation - Uni Kassel · Master’s Thesis Presentation 13, July, 2016. Comparison Of Novel And State Of The Art Solar Cells Author: Adegbenro Ayodeji REMENA

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