Madeleine Breshears
My research focuses on merging data science and machine learning techniques with functional scanning probe microscopy (SPM) to better understand energy materials. We are currently experiencing a convergence of advancement in both data science techniques and scanning probe microscopy resolution and functionality. I aim to take advantage of this confluence to evaluate the spatial heterogeneity of photovoltaic materials. SPM allows us to visualize surface photovoltage, charging rate, chemical composition, and morphology on the nanometer scale. These multimodal techniques produce incredibly dense, multidimensional data that naturally encourage the use of machine learning to extract meaningful information more efficiently. Specifically, I am working on using neural...
Daniel Zhou
Thermoelectric materials, or materials that can convert waste heat into electricity are promising sources for renewable energy. For a thermoelectric material to be efficient, it must have low thermal conductivity and high electrical conductivity. Prime candidates for these materials are Zintl phases which are semiconductors that can exhibit metallic conductivity due to the contributions of ionic and covalent character. Both the cationic and anionic sites of these compounds can be manipulated to tune the electronic and thermal properties. The Velian group has developed redox-active nanoclusters that can be tuned electronically with the addition of different transition metals. I plan on linking these nanoclusters with inorganic...
Ying Xia
The focus of my research will be interface-assisted solution-synthesis of two-dimensional metal-porphyrin monoatomic layers (2D-PML), which are of great interest due to the tunability of their properties. I will use two methods to synthesize metal-porphyrin monoatomic layer structures, one is the hydrothermal method, the other is the water-oil interface assisted method. AFM will be the main characterization method to analyze nucleation and growth mechanisms during the synthesis procedure. Then clean energy applications such as catalysts for hydrogen evolution and electrical capacitance will be studied. Advisor: Jim De Yoreo and Jun Liu - Materials Science & Engineering...
Julia White
Advances in energy storage are a critical aspect of the effort to convert the world to clean energy sources as electrification increases. For applications such as electric vehicles, lithium ion batteries are the best technology available but need to be improved upon further to meet energy density and power demands. Anode-less lithium batteries are extremely promising for drastically increasing energy density and rate capabilities, yet dendrite formation leading to rapid failure remain an obstacle in their implementation. My research will focus on designing ultrathin (<50 micron) 3D current collectors, altering both geometry and chemistry, and examining the mechanism of lithium electrodeposition. The findings will...
Xingyi Wang
Semiconductor crystals that behave exactly as researchers expect are rare, if nonexistent in nature or in lab. Local environment within crystals like defects or surface discontinuities may dominate the properties of semiconductor materials, and often these intractable local impurities limit the performance of clean energy harvest or generation devices like solar cells or LEDs. As part of a collaboration, my project takes a step towards understanding photon generation and loss mechanisms bottom-up by isolating and directly observing single defects within ZnO nanoparticles at atomic level, and correlating their optical properties with theoretical calculations based upon the local environment of single defects. If the observed...
Eden Tzanetopoulos
Lighting accounts for 15% of annual global energy consumption. Due to mounting concerns arising from anthropogenic climate change, there is an increased demand for lighting technologies with higher efficiencies and greater longevity. My research will focus on synthesizing colloidal nanocrystals of Mn4+-doped A2MF6 (A = K, Na, Cs; M = Ti, Ge, Zr) lattices to be used as red-emitting phosphors. These activator-host materials can act as an efficient red component of white LEDs due to their narrow-band ~630 nm emission. Mn4+-doped fluorides have recently been utilized in next-generation lighting technologies, but the nanoscale regime that affords synthetic tunability and narrow emission bandwidth has yet to...
Kathleen Snook
Electrically conductive metal–organic frameworks (MOFs) are important due to their applications in electrocatalysis, energy storage, and electronic devices. However, their synthesis is often poorly developed, resulting in small crystal sizes and a limited understanding of their physical properties. I hypothesize that a critical barrier to their synthesis is uncontrolled ligand oxidation, as conductive MOFs often contain air-sensitive catechol, o-phenylenediamine, and dithiolene building units. During this award period, I will examine the synthesis of π–d conjugated 2D frameworks, an important family of conductive MOFs, via controlled chemical oxidation in an inert atmosphere. I will optimize my synthetic parameters using a design of experiments approach, in...
Yangwei Shi
I will focus on fabrication and characterization of organic-inorganic halide perovskite solar cells which are regarded as a promising photovoltaic technology. My projects include passivation of mixed cation mixed halide wide-bandgap perovskite, aiming to improve the photoluminescence quantum efficiency of perovskite and to achieve a higher open-circuit voltage that approaches the theoretical limit. In addition, I will focus on developing a solution processed recombination layer with matched refractive index and good conductivity for tandem perovskite/silicon solar cell. Based on the low defect density of wide bandgap perovskite and solution processible recombination layer, the efficiencies of tandem perovskite/silicon solar cells can be further increased. Advisor: David...
Ricardo Rivera-Maldonado
Electrocatalysis is a promising means to reduce the climate impacts of the chemical industry by combining renewable electricity, abundant feedstocks, and catalysts made of earth-abundant materials. The study of the surface of electrocatalytic materials is essential for the advancement of the field since all inner-sphere reactions occur at the surface and the surface modulates charge transfer and outer-sphere interactions with solvents, electrolytes, and substrates. Nanoscale catalysts enable these studies due to their high surface-to-bulk atom ratio. My research involves studying transition metal phosphide (TMP) nanoparticles. TMPs have been shown to be excellent catalysts for hydroprocessing and hydrogen evolution, which provide a foundation for developing...
Ramsess Quezada
Organic Mixed Ionic Electronic Conductors (OMIECs) are a set of organic semiconducting materials that conduct both electronic and ionic charge in an electrolyte. When OMIECs are electrochemically oxidized or reduced, counter-ions will enter the film to compensate the electronic charge. This process of ion injection is a crucial one for the optimization of these materials in applications such as organic batteries and capacitors. My research will focus on probing and understanding the electrochemical and electrostatic relationship between these charges in conjugated polymers. Utilizing a wide range of characterization techniques, including XRD and AFM, I will investigate the physical relationship between these electronic and ionic...
Vinh Nguyen
The Internet of Things (IoT) holds immense promise for energy sustainability but has a critical limitation: traditional energy storage cannot meet the power, energy, and size requirements of devices that power the IoT. Batteries that utilize specialized 3D geometries can meet these requirements, but manufacturing these batteries is currently time-intensive, inflexible, and requires laborious post-process integration. I will address these limitations by developing a manufacturing workflow that can print customized, integrated energy storage on-demand. First, I will develop a specialized manufacturing platform with custom printheads and tools. I will use this platform to 3D print a customized battery using a single-step, automated procedure that simplifies...
Christine Morrison
Conjugated polymers are touted for their electronic and photonic properties, and have been shown to have significant applications in light-harvesting and storage. Much research has already been done showing the plethora of applications for conjugated polymers, but there has been considerably less work involving conjugated cyclic polymers. My research is focused on creating an optimized initiator for ring expansion metathesis polymerizations (REMP) for use in the synthesis of conjugated cyclic polymers. Ring expansion polymerizations are a favorable way to approach the production of cyclic polymers as they provide better control over molecular weight, effective conjugation length, and long-range morphology of the polymer. Using REMP...