Phd fellowship funded by the Department of Materials Science on Materials for Energy The student can choose for his Phd thesis any of the experimental or theoretical activities carried out at the Department of Materials Science on the study of materials for solar cells, solid state batteries and supercapacitors, fuel cells, electrochromic devices, hydrogen production and storage. These activities are described at the webpage https://www.mater.unimib.it/en/research/research-areas within the research areas of "Environment and energy materials", "Organic and polymeric materials", and "Microelectronics and photonic materials".
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Phd fellowship funded by the Department of Materials Science on
Materials for Energy
The student can choose for his Phd thesis any of the experimental or theoretical activities carried out at the Department of Materials Science on the study of materials for solar cells, solid state batteries and supercapacitors, fuel cells, electrochromic devices, hydrogen production and storage. These activities are described at the webpage https://www.mater.unimib.it/en/research/research-areas within the research areas of "Environment and energy materials", "Organic and polymeric materials", and "Microelectronics and photonic materials".
The Consortium Corimav in collaboration with Pirelli Tyres finances 3 fellowships for the Phd Program in Materials Science and Nanotechnology on the projects 1) Self-‐assembly of Nanoparticles in Rubber Nanocomposites 2) Study of the Crosslinking Density for Vulcanization Process 3) Innovative Materials for Tyre Application The project will be carried out both in the University labs of the Department of Materials Science and in the laboratories of Pirelli Tyre under the joint supervision of University and company tutors. For information please contact -‐ Dr. Barbara di Credico, Università Milano-‐Bicocca ([email protected]). -‐ Dr. Raffaella Donetti, PIRELLI TYRE ([email protected]). A description of the three projects is given below.
Self-‐assembly of Nanoparticles in Rubber Nanocomposites
University Supervisor: Dr. Barbara di Credico ([email protected]) Pirelli Supervisors: Dr. Luca Giannini, Dr. Luciano Tadiello Polymer nanocomposites (PNCs), prepared by embedding nanoparticles (NPs) into a polymer matrix, received considerable scientific and technological attention thank to their excellent mechanical, thermal, electrical and gas-‐barrier performance These interesting properties are critically dependent on i) the control of the morphology of the aggregates at the local scale within the nanocomposite, ii) the interfacial interactions between polymer and NPs, and iii) the geometrical characteristics of the NPs, such as size and shape. Recently, the dramatic improvements in PCNs properties have been mainly attributed to the ability of filler NPs to self-‐assemble into highly anisotropic structures. The use of anisotropic NPs, like rod-‐like silica and silicate nanofibers, seems to be a potential way of producing an oriented and anisotropic filler assemblies (filler network structures). Interestingly, some experimental evidences suggest that also spherical NPs, uniformly decorated with organic coatings (e.g. small molecules, biomolecules, or polymers), self-‐assemble into a variety of anisotropic structures when they are dispersed in the corresponding homopolymer matrix. In this context, the PhD research activity aims at developing strategies for filler NPs self-‐assembly in rubber nanocomposites in order to improve their mechanical properties. On the basis of recent publications, the anchoring of polymers onto inorganic filler surfaces will be explored to prepare a new class of hybrid building blocks, which combine the characteristics of both inorganic NPs, like silica or silicate, and rubber polymers. Possible synthetic methodologies (e.g. one-‐pot synthesis, “grafting from” and “grafting to” methods) will be studied to prepare polymer decorated NPs. The surface functionality and interparticle interactions of fillers will be evaluated with respect to the grafting density, polymer length and composition, and particle structure, size and shape. Upon incorporation of polymer decorated NPs in the rubber matrix, a comprehensive investigations on the dispersion and assembly of grafted NPs in rubber nanocomposites will be performed by means of a plethora of characterization techniques. The mechanical performance of new nanocomposites will be studied and related with the dispersion and distribution of NPs, before and after the grafting of polymeric components that may template or direct the self-‐assembly process. Finally, the goal of this research activity is to design rubber systems with well-‐defined spatial organization and control the NPs assembly into architectures with desired complexity and functionality in order to tailor material properties for tyre application.
Study of the Crosslinking Density for Vulcanization Process University Tutor: Prof. Roberto Scotti Pirelli Supervisors: Dr Raffaella Donetti, Dr Antonio Susanna The vulcanization is the final chemical step in the tire production process, creating a covalent network and hence fixing the geometry of the tire components and adjusting the key characteristics of them, such as mechanical strength and resistance, interaction with reinforcing components and major performance requirements as the more environmental relevant Rolling resistance or the more safety related braking and handling performance. Although in particular the sulfur vulcanization is an industrially consolidated process, there are still many open questions regarding the reaction mechanism itself and the potential optimization of it. Hence the vulcanization is still matter of continuous scientific research work. The more complex the compound system evolves, the more challenging is the control and guidance of the vulcanization process. In this scenario, the PhD research activity aims at developing different vulcanization agents, majorly metal complexes, anchored to filler particles. These new vulcanization agents target to modulate, by means of their geometry and nature, both the formation and spatial distribution of the crosslinking sulfur chains during the vulcanization process of rubber, starting with more simple model systems and then moving towards more complex and more real compound compositions. The research activity which basically includes the synthesis on new vulcanization agents will be enhanced by the study and investigation of the distribution and the homogeneity of the network-‐chain density in the polymer matrix, by a variety of sophisticated physical and chemical analytical methods, such as MDR, DSC, Mooney–Rivlin, NMR, etc. Finally it will be related the achieved and adjusted crosslink density, by means of new vulcanization activators to the composite mechanical properties.
Innovative materials for tyre application
Multi-‐functionalized molecular systems for the modulation and optimization of silica-‐rubber interaction
University Supervisor: Prof. Antonio Papagni ([email protected]) Pirelli Supervisors: Dr Luca Giannini, Dr Luciano Tadiello In rubber nanocomposites for tyre compound technology, the interaction at silica-‐rubber interface is usually provided by the use of coupling agent such as silane groups, creating covalent bonds between silica surface and polymeric matrix. In this scenario, the aim of this PhD project is to plan and synthesize multifunctional molecular systems able to modulate and optimize the interaction at the silica-‐rubber interface, exploiting the reactivity of specific functional groups. Particularly appealing are functional groups that show a suitable reactivity activated during vulcanization process.
The Institute for Microelectronics and Microsystems (IMM) of the National Research Council (CNR)
finances 3 Phd fellowships on the following projects
1) Advanced dielectric stacks for smart power devices: synthesis, characterization and modelling 2) Memristive devices for brain inspired computing
3) Synthesis and isolation of epitaxial Xenes based on group IV-VI elements
A description of the three CNR-IMM Phd projects is reported in the following pages.
Advanced dielectric stacks for smart power devices: synthesis, characterization and modelling
Supervisor: Dr. Sabina Spiga – CNR-IMM, Unit of Agrate Brianza (MB) ([email protected])
The PhD fellowship is focused on the development of advanced dielectric stacks, based on high-dielectric constant materials, for metal-insulator-metal capacitors suitable for the integration in smart power devices. The activity has a strong industrial interest and is developed in the framework of an EU project under the Horizon 2020 program.
The development of advanced materials, such as high-dielectric constant materials (high-k), has been one of the boosting factors driving the evolution of nanoelectronics in the last 2 decades. High-k dielectrics such as binary and ternary metal oxides (HfO2, ZrO2 and many others) has been used as gate insulator in transistors, as well as functional layers in non-volatile memories, and are today available in commercial products. The atomic layer deposition (ALD) of very thin, conformal and of controlled stoichiometric oxides has definitely been one of the key enablers for this revolution. Today ALD deposited metal oxides are of increasing interest for a variety of new applications, such as Smart Power ICs, MEMS sensors and actuators. This interest calls for further materials research and understanding of the properties of high-k dielectric materials.
The main goal of the PhD program is the development of binary or ternary oxide compounds deposited by ALD having ultra-low leakage current and dielectric constant values in the range 20-40. One of strategies to be explored is the doping of ZrO2 and HfO2 dielectric films to stabilize crystallographic phases exhibiting high-k values. Facilities for the growth of these materials as well as for the fabrication of devices are available in the clean room of the Unit of Agrate Brianza of CNR-IMM; the laboratory is also equipped with advanced characterization techniques for the analysis of the physical, chemical and electrical properties of materials and devices. Further, within the international partnership of the EU project, other materials such as perovskites may be available for extending the study to alternative routes.
The proposed approach include the synthesis of materials, device/material characterization (electrical and physical), as well as the modelling of charge transport properties and defect distribution within the oxides; a commercial specialized software will be made available for the latter purpose.
The student will join a team with an extensive experience in the field and highly committed to expanding knowledge in application-oriented material and device science; she/he will have the chance to develop broad skills ranging from material science to electrical testing and modelling, as well as to enhance her/his expertise in an international framework. Exchange visits with foreign partners will be organized; part of the activity will be carried out in strict collaboration with one of the leading semiconductor industries in Italy and worldwide, with a direct interaction of the student with the company R&D team.
Memristive devices for brain inspired computing
Supervisor: Dr. Sabina Spiga – CNR-IMM, Unit of Agrate Brianza (MB) ([email protected])
The PhD fellowship is focused on the development of memristive devices as new building blocks for advanced brain inspired computing technologies. The activity has a strong interdisciplinary character at the cross-road between materials science, device technology, computer science and neuroscience, and will be carried out in the framework of European Projects and existing international collaborations.
Memristive systems represent a large class of emerging nanoscaled devices that exploits various physical mechanisms to achieve a controlled and persistent conductance variation upon electrical stimuli. Most of the devices have a simple structure where an active organic or inorganic thin layer (e.g. an oxide) is sandwiched between two metal films and can be scaled down to few nanometers. Memristive devices are today of large interest since they can be used to reproduce bio-inspired systems: for example, they can act as dispersed memory elements mimicking the role of synapses in the nervous systems, or as stochastic and non-linear elements of neuronal units. With the further advantage of being compatible with integrated processes of electronic industry, these devices can be used as new building blocks for brain-inspired computing technologies. Thanks to event-driven computation, highly-parallelized non-von Neumann architecture, and spatio-temporal coding, the brain-inspired spiking neural network (SNN) is one of the most promising approach to artificial intelligence. Among the various available memristive technologies, resistance switching memories (RRAM) based on redox reactions and electrochemical phenomena in oxides are very promising because of low power consumption, fast switching times, scalability down to nm scale and CMOS compatibility. For these reasons, RRAM are today investigated as synaptic elements for spiking neural networks.
The main goal of the proposed PhD activity will be the development of RRAM-based nanoscale synapses for spiking neural network. Materials (oxides, nitrides and metals) will be deposited by atomic layer deposition, sputtering and electron beam evaporation; devices will be patterned via optical or electron beam lithography. The electrical testing will be performed both in DC and pulsed regimes to study the switching properties and the evolution of conductance dynamics under various stimuli. Further, modelling of SNN including the developed devices will be performed. Facilities for the growth of materials as well as for the fabrication of devices are available in the clean room of the Unit of Agrate Brianza of CNR-IMM; the laboratory is also equipped with advanced characterization techniques for the analysis of the physical, chemical and electrical properties of materials and devices.
The student will join a team with an extensive experience in the field and internationally positioned in the area of neuromorphic computing; she/he will have the chance to develop broad skills ranging from material science to electrical testing and modelling in an emerging area of research, as well as to enhance her/his expertise in an international framework through the existing collaborations of the hosting group. Exchange visits with international partners (both academic and industrial) will be organized.
Synthesis and isolation of epitaxial Xenes based on group IV-‐VI elements
Supervisor: Dr. Alessandro Molle – CNR-IMM, Unit of Agrate Brianza (MB) ([email protected])
Project(s): XFab (ERC-CoG 2017)
The topic of the PhD thesis will be focused on the development of standardized procedures for the synthesis and processing of new epitaxial Xenes, that is two-dimensional atomically thin crystals made of non-carbon atoms supported by substrates. Xenes have recently come to the research forefront as complementary materials to graphene with X spanning from alternative group IV elements (like silicene, germanene, stanene), to pnictogens (like phosphorene, antimonene, and bismuthene), and chalcogens (like selenene and tellurene). Basic motivation for the Xenes is to outstandingly expand graphene functionalities in nanotechnology.
The research activity will be carried out in the framework of the ERC CoG 2017 grant “XFab” (“Xene fabrication for a new two-dimensional nanotechnology platform”, grant no. 772261) recently assigned to Dr. Alessandro Molle. The project objective is to produce Xene that can be readily integrated into functional devices for applications in nanotechnology. On this background, the identification and isolation of a selected number of Xenes in device-friendly configurations will be a key goal of the PhD activity.
In detail, a specific task will be devoted to the installation of new growth equipment increasing the production capabilities with respect to the current state. A second task will be concerned with the advanced characterization of the grown materials with light- or electron-based spectroscopy enabling the selection of a portfolio of Xenes that will be readily transferred to the device processing step. Overseas exchanges (stages, internships, and access to large-scale facilities) will be scheduled for these purposes.
The overall activity will be pro-actively conducted according to the project roadmap and within a strongly motivated research team (including Researchers, Post-Doc fellows, PhD students). As such, being respectful of project timing and milestones, and working in a team under the coordination of the supervisor will be considered as pre-requisites for the PhD activity.
Istituto per lo Studio delle Macromolecole (ISMAC) of the National Research Council (CNR)
finances 2 Phd fellowships on the following projects 1) Polymer nanoparticle-based aqueous inks for optoelectronic and electronic device fabrication 2) Innovative additives as viscosity modifiers for energy saving lubricants
A description of the two CNR-ISMAC Phd projects is reported in the following pages.
Polymer nanoparticle-‐based aqueous inks for optoelectronic
and electronic device fabrication Supervisor: Dr. Silvia Destri, Research Director ([email protected]) POPLAB -‐ Photonics and Optoelectronics Group, CNR-‐ ISMAC, Research Unit of Milano The focus of this project will be the fabrication of active layers in electronic and optoelectronic devices processed in aqueous medium, exploiting the preparation of semiconducting material-‐based polymer nanoparticles. In particular, this approach will be studied for the preparation of organic solar cells (OSCs), moreover it could be extended to other kind of device fabrication (e.g. OLED, OFET, etc). Water-‐processable polymer-‐based nanoparticles can be prepared though a miniemulsion process, in which the hydrophobic material (in our case a blend of p-‐type and n-‐type semiconducting materials) dissolved into an organic solvent immiscible with water and properly emulsified with an aqueous phase in order to obtain a miniemulsion. Then the organic solvent can be removed through a mild heating of the so-‐obtained miniemulsion, and recovered if it is necessary. This approach leads to achieve stable colloidal suspensions of nanoparticles consisting of the starting material blend. The deposition and thermal treatment of these colloidal suspensions allows to obtain homogeneous and compact active layers. In literature many papers reported on the use of miniemulsion approach using a large amount of surfactants to stabilize the aqueous/organic solvent interface. These surfactants display an insulating behavior and have to be removed at the end of the procedure by means of dialysis. Recently the ISMAC-‐CNR research group developed the preparation of polymer-‐based colloidal suspensions through miniemulsion approach using amphiphilic rod-‐coil block copolymers, bearing a rigid block (a p-‐type semiconducting polymer) and an hydrophilic flexible segment able to interact with aqueous medium, and at the same time with n-‐type fullerene or non-‐fullerene semiconducting materials (DOI 10.1002/adsu.201700155). Amphiphilic rod-‐coil block copolymers are characterized by the capability to self-‐assemble, leading to make organized nanostructures, under specific conditions. The hydrophilic flexible block behaves as surfactant thus ensuring the colloidal suspension stability, and it interacts with the electron acceptor (n-‐type) material, producing within the suspended nanostructures pre-‐aggregated domains with suitable dimensions for the separation and collection of the charges in the device active layers. The mild annealing of the water-‐processed nanoparticles provides thin films on different substrates (e.g. ITO, PEDOT:PSS, ZnO, etc.) that will be studied as active layers in polymeric solar cells. Low band-‐gap copolymers will be considered as electron donor materials in order to enhance the solar radiation absorption. Possibly materials endowed of partial crystallinity (degree of structural order in solid state) will be selected to investigate the nanoscale structural organization of the p-‐type material within of the water-‐processable nanoparticles. PC71BM and other n-‐type macromolecular compounds will be studied as acceptors. OPV cell prototypes will be prepared on flexible substrates with the aim to produce large area modules, thus the scale-‐up of the material synthesis and processing will be tune in collaboration with the ENI researchers.
Innovative additives as viscosity modifiers for energy saving lubricants
Supervisor: Dr. Laura Boggioni, CNR-‐ISMAC, Via E. Bassini, Milano ([email protected]) Co-‐Supervisor: Dr. Incoronata Tritto, CNR-‐ISMAC, Via E. Bassini, Milano ([email protected]) University Tutor: Prof. Angiolina Comotti The technological evolution of lubricants and in particular of automotive lubricants goes towards products that contribute to the reduction of CO2 emissions through the improvement of energy efficiency. In this evolution, the lubricant additives, such as the Viscosity Modifiers (Viscosity Index Improvers) play a crucial role. The Viscosity Modifiers (VMs) are polymeric additives used to optimize the viscosity of the oils in all the temperatures range at which VMs operate. In particularly the VMs have the function to increase the viscosity of the oils at high temperature (thickening power) limiting as far as possible any increase in low-‐temperature viscosity. These additives must also be stable and retain their functions when the oil is employed in an engine. By this, a good VM must also have an optimal mechanical shear stability. The most common VMs additives are based on ethylene-‐propylene linear copolymers (OCPs) and, although still used in many oils, OCPs show signs of weakness in lubricants of advanced technology, which has to be in compliance with the new international specifications especially in terms of engine tests performances and energy efficiency (fuel economy). It is therefore very important to identify a new class of VMs that overcomes the problems of OCPs and allows the production of technologically advanced lubricants with high fuel economy. The purpose of the project is to study and develop polymers characterized by better mechanical shear stability, thickening efficiency and low temperature performances than OCPs. The research activity will concern the synthesis and the performance evaluations of new polymeric materials with singular structures such as star shape or dendrimer, containing a core linked to arms based on styrene/diene or other copolymers. This study will include the use of different types of polymerization such as anionic or others, that will be combined with "Arm First" or “Core First” techniques. Polymers will be characterized by NMR, GPC and DSC techniques. The project activities will be carried out in the ISMAC laboratories and also in the Eni Research Center of San Donato Milanese.
Contratto di apprendistato di alta formazione presso Glass to Power S.r.l Sede di lavoro: Milano
Sviluppo di nanocristalli colloidali a semiconduttore ad elevato Stokes- shift per concentratori solari luminescenti
I concentratori solari luminescenti (LSCs) sono dei dispositivi fotovoltaici composti da una guida d’onda polimerica drogata o ricoperta con fluorofori altamente emissivi. La luce solare diretta e/o diffusa è assorbita dai fluorofori che la riemettono a lunghezze d’onda maggiori all’interno della matrice. La luminescenza è quindi guidata tramite riflessione totale interna fino a raggiungere i bordi della guida d’onda dove è convertita in elettricità da piccole celle fotovoltaiche poste lungo i bordi perimetrali. L’efficienza del dispositivo è determinata da una serie di processi fisici riguardanti sia la matrice sia i fluorofori. Ad esempio, un elevato coefficiente di assorbimento su tutto lo spettro visibile e un’alta resa quantica di fotoluminescenza dei fluorofori sono necessari mentre il riassorbimento della luminescenza da parte dei fluorofori stessi e della matrice, nonché fenomeni di diffusione della luce, comportano perdite di efficienza. Questi requisiti possono essere simultaneamente soddisfatti dai nanocristalli colloidali a semiconduttore (NC) che presentano elevate efficienze di luminescenza, un alto coefficiente di assorbimento su tutto lo spettro visibile e una lunghezza d’onda di emissione selezionabile tramite le dimensioni. Inoltre, a differenza rispetto ai fluorofori organici tradizionali, ingegnerizzando opportunamente i NC, è possibile ottenere un’elevata separazione spettrale tra i profili di assorbimento ottico e di emissione (comunemente indicata col termine Stokes-shift), che riduce drasticamente le perdite ottiche dovute a riassorbimento in particolar modo in LSC di grandi dimensioni. Sulla base di queste potenzialità, Glass to Power è impegnata a industrializzare i processi di sintesi di NC e di fabbricazione di guide d’onda nano-composite basate su polimeri acrilati contenenti NC. Allo stato attuale, nonostante i grandi passi avanti ottenuti recentemente, rimangono aperte problematiche di rilievo principalmente associate all’ottimizzazione dell’efficienza di emissione dei NC, la loro compatibilizzazione con la matrice polimerica e la stabilità delle proprietà ottiche agli iniziatori radicalici utilizzati per la fabbricazione di LSC tramite polimerizzazione in massa. Il progetto sarà quindi focalizzato sullo sviluppo della sintesi di NC con assorbimento ottico esteso su tutto lo spettro visibile e emissione nel vicino infrarosso in modo da ottenere LSC efficienti ed incolori adatti all’integrazione architettonica sotto forma di finestre fotovoltaiche. Saranno quindi investigate varie classi di NC che presentano un elevato Stokes-shift, tra cui semiconduttori ternari, come il CuInS2, calcogenuri binari drogati con impurezze metalliche e i NC di perovskiti di più recente sviluppo. Nuove procedure sintetiche e di passivazione inorganica tramite etero-strutturazione saranno investigate al fine di ottimizzarne l’efficienza di fotoluminescenza e la fotostabilità verso il processo di fabbricazione, limitando comunque il riassorbimento. Per la sintesi colloidale sarà principalmente utilizzata una Schlenk line, mentre la caraterizzazione del materiale sarà focalizzata sull’investigazione delle proprietà ottiche, come l’assorbimento ottico e la fotoluminescenza tramite tecniche in continua e risolte in tempo. Supervisor Universitario: Dott. Angelo Monguzzi, [email protected] Per informazioni: Prof. Sergio Brovelli, [email protected]
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