(3ip) Dynamic Transformations in Colloidal Semiconductors for Scalable Energy Technologies

Nanomaterials exhibit distinct phenomena from the bulk, such as tunable interfaces, charge localization and quantum confinement. However, integrating nanomaterials into technologies is hampered by difficulties controlling transformations during synthesis and operation. My vision is to develop experimental frameworks to explore multi-scale transformations in optoelectronic nanomaterials. Specifically, my group would target: (1) harnessing electrochromism as a scalable indicator to understand rapid transformations in next-generation electrochemical systems, and (2) investigating colloidal interactions that direct microstructure of solution-processed hybrid 2D semiconductors with tunable light-matter interactions. We would use high-throughput synthesis and correlated in situ optical spectroscopies of dynamics to discover material design rules through traditional and big-data analysis.

Post-doctoral Research: My post-doctoral research, with Prof. Michael Chabinyc at the University of California, Santa Barbara, has investigated 2D layered hybrid perovskite materials for solution-processed optoelectronic devices. These materials are tunable and robust analogues of lead halide perovskites (e.g. MAPbI₃), which show exceptional promise for low-cost solar technologies. 2D perovskites are composed of atomically-thin layers of semiconducting sheets separated by insulating spacer molecules. This anisotropic structure is a ‘bulk’ quantum nanomaterial, because lead halide sheets demonstrate quantum confinement with tunable optical and electronic properties My work resolved problematic solvent interactions during film deposition that lead to phase impurities and disordered quantum well nanostructure. More recently, I have explored the colloidal interactions that govern crystal growth, and dynamic interactions between organic and inorganic moieties in layered hybrid perovskites through NMR spectroscopy to uncover molecular design rules for this intriguing class of 2D materials.

Pre-doctoral Research: My pre-doctoral work with Prof. Delia Milliron at the University of Texas at Austin explored the electrochromic effect in metal oxide nanocrystals. I discovered that distinct electrochemical charging processes, such as surface capacitance, ion insertion, or metal-insulator transitions, cause independent colorations in nanocrystal films. During my studies of TiO₂ nanocrystals, I resolved independent infrared and visible electrochromic responses that can be harnessed for energy efficient ‘smart windows’. These modulations can be attributed to either capacitive charging – inducing a tunable plasmonic interaction with light – or Li insertion, which causes local polaronic defect modes that absorb visible light. Building on these observations, I explored how charging and coloration phenomena in correlated and plasmonic oxides are sensitive to nanocrystal size, shape and doping. These studies revealed the potential for full-spectrum in situ optical spectroscopies to probe local transformations in nanomaterial ensembles, from the nano- to macroscopic scale.

Teaching Interests

My goal as an educator is to make the process of learning transparent and structured within an inclusive learning environment. Presenting subject matter in a well-bounded approach, with consistent low-stakes feedback, allows students to engage with the material to the best of their own abilities. I find that this structure provides grounding to pursue deep questions with curiosity and inclusion, and an efficient mechanism to deliver content for scientific curricula. During my graduate studies I assisted with the development of two chemical engineering courses from the ground up: an undergraduate survey class in materials science and a graduate elective course in solid-state materials physics. I am deeply invested in improving my science and engineering teaching pedagogy, and I took graduate courses in engineering curriculum design and assessment to develop effective tools and practices. I employed these skills as a teaching assistant by incorporating simple feedback channels in both classes, including peer-directed projects, low-stakes quizzes and mid-semester surveys. As a mentor to several undergraduate and graduate students, I have also strived for open communication and regular feedback to ensure a productive relationship.

My work frequently recalls my chemical engineering training, and I would use my research experience as a teaching device within the canonical chemical engineering curriculum. I am particularly interested to teach core thermodynamics courses and elective solid-state courses on optoelectronic and electrochemical materials. I am also eager to apply my experience of kinetics and phase behaviors of solution- and solid-state systems to courses on reaction kinetics, continuum transport and material separations. Beyond the classroom and laboratory, I have been a consistent advocate of STEM education for under-represented and resource-limited communities through my participation in on-campus outreach events. I devote great effort and enthusiasm to the STEM education 501(c)3 non-profit that I co-founded and continue to supervise as a board member, called Emerging Leaders in Technology and Engineering. As a faculty member I will continue to seek opportunities to advance equity, inclusion and diverse representation in science, both locally and in the broader scientific community.


AIChE 2020 Presentation

“Electrochromism as an in Operando Tool to Deconvolute Dynamic Li-Ion Charging Processes in Nanocrystal Electrodes.”
Q&A Time: 8:00AM Pacific Time – 9:00AM Pacific Time
Category: PreRecorded+, Materials Engineering and Sciences Division (08).
Length: 15 minutes