Previous Winton exchange visitors
Previous Exchange Visitors
Examples: Participants 2019
Supervisor: Dr. Akshay Rao, Winton Fellow and Optoelectronics Group, Department of Physics, University of Cambridge
Host: Professor Jeffrey Neaton, Department of Physics and Kavli ENSI, UC Berkeley
Biography
Antonios completed his BSc in Physics in 2014 at the National and Kapodistrian University of Athens and MSc in Organic and Molecular Electronics at the Technische Universität Dresden. He is currently a Ph.D. student in the Rao group researching light emission and charge generation in organic solar cells and LEDs from a theoretical perspective.
Exchange Proposal
The project “Phonon effects in solid state singlet fission” will investigate the effect that vibrations in solid-state structures of organics semiconductors have on single exciton fission, which is a process that can be utilized in solar cells to increase device efficiency. The research will aim to provide an accurate description of the electronic structure of materials suitable for singlet fission and then calculate the effect of vibrations on their properties. The final phase of the work will be to model the real-time dynamics of singlet fission in a solid with the insight used to inform how to improve the performance of solar cells.
Supervisor: Professor David Limmer, Chemistry Faculty and Kavli ENSI, UC Berkeley
Host: Professor Dr. Alpha Lee, Winton Fellow, and Theory of Condensed Matter Group, Department of Physics, University of Cambridge
Biography
Chloe obtained a BS in Macromolecular Materials and Engineering from Fudan University, before moving to the Limmer group at UC Berkeley in 2016 as a graduate student. Her research is on developing a theoretical description of generic nonequilibrium processes, especially for systems where macroscopic laws that govern their properties break down and microscopic fluctuations become important. She studies large deviation functions (LDF) that are used to characterize the fluctuations around nonequilibrium steady states.
Exchange Proposal
In her research in the Limmer group, she has developed a method to compute transport coefficients using large deviation functions (LDFs). This method relies heavily on the accurate evaluation of LDF and can be costly and inefficient for complex systems. As an alternative approach to tackling these complex problems, she will work with the Lee group in Cambridge to develop enhanced sampling algorithms employing machine learning to estimate LDFs. Once a machine learning aided sampling algorithm is devised, it can be used to study complex chemical system such as transport in ionic liquids based supercapacitors.
Supervisor: Professor Alex Zettl, Department of Physics and Kavli ENSI
Host: Professor Ulrich Keyser, Biological and Soft Systems Group, Department of Physics, University of Cambridge
Biography
Matt studied Physics at the University of Florida and received his BSc in 2013. He then moved to the Zettl group at UC Berkeley where he is studying towards a Ph.D. His research is on chemical synthesis and direct-write nanostructuring of the two-dimensional (2D) materials, graphene and hexagonal boron nitride (h-BN).
Exchange Proposal
In this project, he will bring his expertise on creating structural devices using 2D materials and work with the Keyser group and Dr. Hannah Stern to work on two projects to couple h-BN defects and pores to the outside world. The first will be to perform DNA translocation experiments on nanopores made with atomic precision. The second will be to perform correlated microscopy studies of quantum emission from h-BN defects that will be first imaged with HR-TEM at Berkeley and then bring them to Cambridge to correlate the atomic structure with the local fluorescence.
Supervisor: Professor Jeffrey Neaton, Department of Physics and Kavli ENSI
Host: Dr. Bartomeu Monserrat, Winton Fellow, and Theory of Condensed Matter Group, Department of Physics, University of Cambridge
Biography
Stephanie obtained her BSc from the University of Ottawa in 2013, specializing in Physics. She then joined the Neaton group completing her Masters in 2015 and currently studying towards a Ph.D. Her research is on Density Functional Theory (DFT), examining topological and electronic properties of complex materials.
Exchange Proposal
In this project, the first-principles based techniques that Stephanie has utilized to date will be expanded through working with experts in Cambridge in structure prediction and advanced electron-phonon coupling techniques. These techniques will be applied to exploring how electronic and topological features can be manipulated with pressure in materials. The pressure is known to have enormous effects on material properties, but its use for tuning topology remains an open field that could yield surprising results for controlling these unique properties for future device functionality.
Supervisor: Professor Jeremy Baumberg, Department of Physics, University of Cambridge
Host: Professor Paul Alivisatos, Department of Chemistry and Kavli ENSI, UC Berkeley
Biography
Alex studied Physics at Manchester University, completing one year of his Master's course at the National University of Singapore. He then joined the Graphene doctoral training center and is working in the Baumberg group where he is studying the excitation kinetics of layered materials in coupled plasmonic nanocavities.
Exchange Proposal
Plasmonic nanogaps can be formed by having Au nanoparticles on an ultrathin material (0.4 – 10nm) placed onto an Au ‘mirror’. The material acts as a spacer between the nanoparticle and Au ‘mirror’. In this way the field is confined to below the diffraction limit inside the spacer material, leading to large field enhancements (up to ~104). Irradiation of this nanoparticle-on-mirror (NPoM) system enables novel interactions with the field, and scattering gives us information on how the material interacts with this field. This proposal aims to combine work in the Alivisatos group on the modification of Au nanoparticles in graphene liquid cells with plasmonic techniques from the Baumberg group.
Supervisor: Professor Michael Crommie, Department of Physics and Kavli ENSI, UC Berkeley
Host: Professor Stephan Hofmann, Department of Engineering, University of Cambridge
Biography
Hsin-Zon completed his BA and PhD in Physics at UC Berkeley in 2012 and 2017 respectively. He is currently a postdoctoral researcher in the Crommie group in the Department of Physics, UC Berkeley. His research has been focussed on making and studying a range of low dimensional materials, including molecular nanostructures, graphene and transition metal dichalcogenides.
Exchange Proposal
This project will combine electron microscopy and local probe microscopy to characterize the synthesis process and post-growth atomic structure. Hofmann group at the University of Cambridge have unique expertise on growth dynamics and electron microscopy. Hsin-Zon will work closely with the Cambridge team to investigate novel synthesis and patterning of 2D material heterostructures, transition metal dichalcogenides (TMDs) and covalent organic frameworks (COFs) using gas injection equipped scanning electron microscope and image seeding and subsequent propagation of the growth.
Supervisor: Professor Tsu-Jae King Liu, Electrical Engineering and Computer Sciences Department and Kavli ENSI, UC Berkeley
Host: Dr. Giuliana Di Martino, Winton Fellow and Nanophotonics Group, Department of Physics, University of Cambridge
Biography
Alice completed her BASc in Engineering at the University of Toronto and then moved in 2015 to UC Berkeley to study for her PhD. Her research interests are in sustainable low-energy computing and developing ultra-low voltage micro-electro-mechanical (MEM) switches and circuits.
Exchange Proposal
In this project, Alice will explore the properties of the valence change mechanism (VCM) memristive switches that have high endurance and energy-efficiency. The systems require optimization and a better understanding of filament development and dissolution. To study these process non-destructive optical techniques, developed in the Di Martino group will be utilized to reveal real-time information about the formation of oxygen vacancies in a model materials stack of TiN/HfOx/Au nanoparticle.
Participants 2018
Supervisor: Dr. Sam Stranks, Optoelectronics Group, Cambridge
Host: Dr. Edward Barnard, Molecular Foundry, LBNL
Biography
Camille is a Doctoral researcher investigating the photophysics of perovskite materials for novel solar cell and LEDs. Originally a theoretical physicist with a BSc in Fundamental Physics from the University Paris VI which included an exchange year at the National University Singapore, followed by a Masters in Condensed Matter from Paris VI and the University of Uppsala, Sweden.
Exchange Proposal
The project aims to “Explore non-radiative loss mechanisms and recombination pathways in metal-halide perovskite through 3D photoluminescence tomography.” The Strank’s group recently found that light and atmospheric treatments on polycrystalline perovskite thin films resulted in large enhancements in the luminescence of the dark grains, with macroscopic optoelectronic properties approaching those of the best crystalline semiconductors reported to date. The visit of Camille for three months would enable samples produced in Cambridge to be studied with subsurface two-photon microscopy, a technique pioneered by Edward Barnard to study photovoltaic materials. The results may lead to a detailed understanding of the charge dynamics that are crucial for further improvements in device performance of perovskite-based solar cells and LEDs.
Supervisor: Professor Ulrich Keyser, Biological and Soft Systems Group, Cambridge
Host: Professor Alex Zettl, Department of Physics and Kavli ENSI
Biography
Mustafa is a Doctoral researcher studying “Single Molecule Detection through a 2D membrane”. During his undergraduate studies, electronic engineering at the University of Southampton, he was involved in a range of healthcare projects including developing a point of care diagnosis equipment. In his Master project, he designed and built a real-time Raman spectrometer, before coming to Cambridge to study an MRes in Graphene Technology.
Exchange Proposal
The project is closely linked to the Ph.D. research of Mustafa, to understand and control ionic selectivity across semi-permeable membranes that are crucial to key applications such as batteries and reverse osmosis power generation. Within the Keyser group, he is studying the behavior of graphene and hexagonal boron nitride (hBN) as 2D porous membranes, utilizing intrinsic defects within chemical vapor deposition (CVD). The Zettl group also has a wealth of expertise in creating, imaging and manipulating nanopores using a different technique involving TEM drilling and dielectric breakdown pore creation. This project will provide an opportunity to explore the benefits and drawbacks of the respective methods and apply these to studies of ionic flux across these membranes to study the reverse osmosis process.
Supervisor: Professor Richard Friend, Optoelectronics Group, Cambridge
Host: Professor Peidong Yang, Department of Chemistry and Kavli ENSI
Biography
Aditya completed his Ph.D. in Physics in 2015 in Cambridge investigating photo-physical properties of hybrid perovskites using photothermal deflection spectroscopy (PDS). Prior to this, he completed a Masters in Nanoelectronics at the University of Manchester and a BEng at the University of Mumbai, India. His research on thin-film semiconductors has led to the understanding of the role of defects in semiconductors. Furthermore, his work on LEDs has produced the highest luminescence efficiency at the time for perovskite-based LEDs. Outside of his research, he is involved in outreach projects to propagate STEM education in schools situated in remote corners of India, UK, and Africa.
Exchange Proposal
The advent of perovskite semiconductors has brought a paradigm shift in semiconductor science and technology opening up a unique set of opportunities to realize novel high performing optoelectronic applications. The magic of these polycrystalline thin-film perovskites is their demonstration of intrinsic semiconductor behavior, perfect clean characteristics and low disorder similar to those obtained in extremely purified single crystals of inorganic semiconductors. Aditya’s research at Berkeley is to synthesize and explore lead-free perovskite semiconductors based nanostructures like nano-crystals, nano-wires, and nano-platelets. There are various synthesis routes available for making this possible and Prof. Yang’s group has strong expertise on this front. Aditya’s extensive expertise in working with perovskite-based semiconductors will be deployed to studying their vastly varying photo-physical properties for applications including solar cells, LEDs and FETs.
Supervisor: Dr. Akshay Rao Optoelectronics Group, Cambridge
Host: Professor Naomi Ginsberg, Department of Chemistry and Kavli ENSI
Biography
Hannah obtained a BSc in Chemistry, from the University of Otago, New Zealand graduating top of the year. She then completed a Ph.D. with Professor Richard Friend in the Optoelectronics Group of the Physics Department, Cambridge, as a Winton Scholar. Currently, she holds a Junior Research Fellow at Trinity College, Cambridge since July 2017. Working between the groups of Professor David Klenerman and Dr. Steven Lee in the Chemistry Department, Professor Stephen Hoffman in the Department of Engineering and Dr. Akshay Rao in the Physics Department. Her research focus is to investigate using super-resolution photoluminescence techniques to probe defect states and structural heterogeneity in 2D material systems.
Exchange Proposal
While in Berkeley Hannah worked primarily within the group of Professor Naomi Ginsberg, using a combination of diffraction-limited optical spectroscopic techniques to probe quantum emission in monolayers of hexagonal boron nitride (h-BN). h-BN is a 2D wide band-gap semiconductor that has recently been shown to display bright room-temperature single photon emission in the visible, sparking immense interest in the material as a solid-state quantum emitter for use in quantum communications. As part of this work, in collaboration with The Zettl research group in Berkeley, Hannah is investigating the structural properties and morphological dependence of h-BN single photon emission.
Department of Chemistry, Cambridge
Host: Professor Jeffrey Neaton, Physics and Kavli ENSI and Professor Xiang Zhang, Mechanical Engineering and Kavli ENSI
Biography
Stephen is Professor of Chemical Physics, a position he has held since 1999 and Fellow of Trinity College, Cambridge. His research involves computational modeling of functional materials to gain a basic atomistic understanding of their physical properties. His research has included studying materials for non-volatile ‘phase-change’ random-access memory for flash-replacement applications. More recently he has demonstrated, via finite-element computer modeling, ‘thermal metamaterials’ that can be used to construct thermal waveguides that confine propagating heat and can, therefore, be used to steer heat along complex geometric paths.
Exchange Proposal
The aim of the exchange is to extend Stephen’s research interests in thermal functionality of materials to thermoelectric generation (TEG) for energy-harvesting applications. He plans to use a DFT-based computational approach to design and discover new (families of) TEG materials with ‘engineered’ optimized thermo-electric and cognate properties in the first instance. To establish this new research the exchange will enable learning at first-hand about various relevant techniques employed by researchers at Kavli ENSI, and to forge collaborations with colleagues there which will further strengthen links between the Winton Programme for the Physics of Sustainability and Kavli ENSI.
Participants 2017
Supervisor: Dr. Felix Deschler, Optoelectronics Group and Dr. Hannah Joyce (Department of Engineering), Cambridge
Host: Professor Jim Schuck, Molecular Foundry, LBNL
Biography
Lissa completed in 2015 her BA Natural Sciences and MSci Physics at University of Cambridge. She is currently a member of the Centre for Doctoral Training in Nanoscience and Nanotechnology (NanoDTC). Her Ph.D. project aims to synthesize metal halide perovskite nanowires and to study their optoelectronic properties using high spatial resolution optical spectroscopy.
Exchange Proposal
The project “Imaging of phonon modes in low-dimensional lead-halide perovskite materials”, was performed in Jim Schuck’s nano-optical imaging group at the Lawrence Berkeley National Laboratory to further her Ph.D. work on the photophysics of metal-halide perovskite nanostructures. Understanding the fundamental properties of these semiconductors is vital to their future applications in photovoltaics and other optoelectronic devices. Therefore, in order to track the rise and fall of the phonon population in the materials after photoexcitation, a time-resolved anti-Stokes Raman experiment was set up, with a high spatial resolution made possible by their microscope facilities.
Supervisor: Professor Richard Friend, Optoelectronics Group, Cambridge
Host: Professor Eli Yablonovitch, Department of Electrical Engineering and Kavli ENSI
Biography
Luis studied Physics on an exchange program that included the University of Salamanca, University of Santiago de Compostela and the University of Bristol. He then went on to complete a Masters and Ph.D. in Physics as part of the Nanotechnology doctoral training center, the University of Cambridge where he studied light and electron propagation in perovskite solar cells.
Exchange Proposal
The project aims to develop a thermophotonic based device for cooling which can have applications in areas such as vaccine transport. The device combines an LED with a solar cell inside an insulated container, based on the concept developed by Professor Yablonovitch. The LED cools itself in the process of light emission and illuminates the solar cell which, in turn, recharges the battery. In this process, heat is transferred from the LED attached to the side to be cooled to the solar cell in the form of light and is dissipated into the atmosphere. Luis subsequently was awarded a Heising-Simons Postdoctoral Fellowship at UC Berkeley to continue his research on developing a thermophotonic bottle for vaccine delivery and a related project on thermophotovoltaic devices that transform heat into electricity, using light as the heat transfer medium.