Aaron Gehrke
Thin-film photovoltaics such as Cu(In,Ga)Se2 (CIGS) and CdTe are among the most promising solar cell technologies. We study these materials using computational materials methodologies, such as density functional theory (DFT), molecular dynamics (MD), kinetic lattice Monte Carlo (KLMC), and continuum-scale models. One of my primary goals is developing atomistic models of diffusion in these materials, for both native species and extrinsic dopants. Knowledge and control of diffusion is necessary for optimizing device performance, such as In/Ga interdiffusion in CIGS, which must be understood to spatially tune the bandgap. I use DFT to predict defect formation energies, defect complex binding, and defect migration barriers. These results...
Andrei Draguicevic
I'm a second-year graduate student in the Velian lab, where I'm working on heterogenous single-site catalysts for environmentally relevant reactions. My research is focused on using black phosphorus, a 2D van der Waal material, to support single metal atoms to create distinct and tunable active sites on a heterogenous support. Currently, I am using hydroformylation as a test reaction to probe this system, where Rh atoms are supported onto the black phosphorus surface to catalytically convert olefins into aldehydes. Advisor: Alexandra Velian - Chemistry...
Jonathan DeStefano
I utilize materials synthesis and thermodynamic, magnetometric, and transport measurements to study materials with non-trivial topological band structures. These materials host surface states which hold promise for applications in a wide variety of fields including quantum computing and next-generation electronics. Of particular interest to me is the interplay of these surface states with magnetism or superconductivity. I hope to develop a deeper understanding of these materials, thus pushing them closer to being used in technical applications. Advisor: Jiun-Haw Chu - Physics...
Yuri Choe
My project is to create hybrid organic-inorganic membranes with greater stabilities at high temperatures and/or with organic solvents. To reduce the energy consumption and associated emissions from industrial thermal chemical separations, switching to membrane separations could reduce energy required by up to 90%. However, commercially available membranes are unstable in many industrial applications. To produce more resilient membranes, I am exploring the use of vapor phase infiltration (VPI) to enhance stabilities of separation membranes and enable its integration into current industrial manufacturing processes without the need for significant changes. My goal is to develop new VPI process chemistries and test properties of the synthesized...
Hannah Contreras
Highly efficient, financially feasible solar photovoltaic technology is crucial to the global transition from fossil fuels to renewable energy to mitigate climate change. Perovskite solar cells (PSCs) represent a promising next generation technology; they have already matched the efficiency of the current market-dominant silicon technology in just a decade of research. Widespread, viable commercial application of PSCs requires stable, scalable device structures to maintain efficiency over time. My goal is to enhance PSC stability and efficiency by studying charge carrier recombination and defect dynamics in the charge transport and active layers of PSCs through extensive device fabrication and subsequent spectroscopic characterization. Advisor: David Ginger -...
Matthew Chang
Information and communications technology (ICT) is predicted to comprise 30% of the world's total energy consumption by 2030. Because of the increasing demand in telecommunications and other relevant technologies, more efficient nanophotonic devices will need to be made industrially. One such device is the Faraday isolator, an optical device that allows the transmission of light in one direction while blocking it in the opposite direction. Yttrium iron garnet (YIG) is a staple ferrimagnetic Faraday isolator material. However, the processability of YIG is lacking due to it mainly being grown as a single crystal. Currently, I am in the process of perfecting a hydrothermal synthesis...
Tyson Carr
I research the fundamentals of anode-electrolyte interactions in Li-ion batteries, in order to enable use of high-capacity, next-generation alloying electrode materials. Standard graphite anodes have up to an order of magnitude lower theoretical capacity than alloying materials such as silicon. However, the volume expansion in these materials as they store lithium ions causes the capacity to fade as they are charged and discharged. My research specifically involves modifying the electrode interface to dynamically mitigate the effects of the volume expansion, while still allowing reversible lithium ion storage to proceed. While the current model system is with silicon electrodes, my research will inform adaptation of...
Jared Abramson
Approximately 250,000 metric tons of nuclear waste currently sit in short term storage around the world with the US accounting for over 90,000. Deep geologic repositories (DGRs) are widely considered the best solution to dispose/storge this waste. The general design of DGRs is widely agreed upon, but some specific aspects optimum design is still uncertain and understudied. One of these aspects is the cement that is used as containment and backfill in some DGR designs, including the design that was implemented in the US at Yucca Mountain until recently. My research focuses on studying different cement formulations to understand how the cement will contribute...
Duncan Reece
Hydrogen is being developed more and more as a sustainable fuel. The combustion of hydrogen produces no carbon emissions and it is suitable for use in gas turbines, internal combustion engines, and fuel cells. However, the primary source of hydrogen is fossil fuels. The focus of my research is developing new ultra-thin films with highly specific structures and properties to improve the efficiency and reaction kinetics of hydrogen production from water electrolysis. Yet, water electrolysis is still too energy-intensive and expensive to compete with current methods. Density functional theory has shown that the slow kinetics of the oxygen evolution reaction, the rate-limiting step of electrolysis, can...
Tharindu W. Fernando
I will use computational and theoretical approaches to understand and predict topological effects of materials in their optically excited states. Currently, I am wrapping-up an investigation on a novel interband index T for 2D systems (such as transition metal dichalcogenides). We showed that T may provide gauge-invariant excitonic optical selection rules and help characterize valley topology in excited states. Next, I will develop robust DFT-based computational schemes to calculate T in other materials beyond tight-binding frameworks. I will simultaneously study T in non-Hermitian systems; which are realistic quantum systems with gain and loss due to interactions with optical fields and environments. I am interested...
Jiayi Li
I will work on large-scale integration of renewable energy resources such as rooftop solar PV: specifically, I will develop state-of-the-art tools at the intersection of machine learning and power system control to safely and efficiently integrate distributed energy resources. A motivating application for me is the integration of solar PV into the distribution system. They can both create large and rapid voltage fluctuations, as well as correcting them using inverter interfaces. Optimizing the actions of inverters is complex and computationally very challenging. Machine learning can be very helpful in designing the controllers but due to the uncertainty and volatility of the system, existing methods do...
Yifei He
Conjugated polymers (CP), a solution-processable and mass-producible semiconducting material, are a promising candidate in the application of organic solar cells. One important factor that determines the light-electricity conversion efficiency of CPs is the morphology. My research will thus primarily investigate the method to control the microstructure of the thin films via accurate copolymerization. The ultimate goal of my project is to establish the knowledge about the relationship of molecular structure-morphology-optoelectronic performances, which contributes to the future design of high performance polymers in solar cells that could be mass manufactured. Advisor: Christine Luscombe - Materials Science & Engineering...