MSE Seminar Series: Qiuming Yu (Cornell)

Description

Tailoring Light-Matter Interaction for Nanobiosensing, Solar Energy Harvesting and Circularly Polarized Light Detecting

Tailoring light-matter interaction with nanostructured plasmonic materials and thin film semiconductors has led to the development of new technologies for broad applications from biomedical diagnostics to sustainable energy. Our recent efforts have been focusing on the development of plasmonic nanostructures for biosensors based on surface plasmon resonance and surface-enhanced Raman scattering, organic-inorganic hybrid metal halide perovskites for photovoltaic cells, and two-dimensional chiral hybrid halide perovskites for direct detecting circularly polarized light (CPL). In this talk, I will highlight our recent work on chiral perovskites and their applications for CPL photodetectors. As ionic semiconductors, the flexible crystal structures and tunable compositions make it possible to rationally design hybrid perovskites with desired properties. Chiral perovskites demonstrate such possibility and the breakthrough with respect to the development of a new class of chiral semiconductors, which opens up new applications of hybrid perovskites to chiroptoelectronics, ferroelectrics, and spintronics. We demonstrate that the chirality of 2D halide perovskites can be widely tuned via incorporation of mixed chiral and achiral organic ligands in the organic layer. A broad range of alkyl and aryl chiral and achiral cations are used in forming 2D chiral halide perovskites. Additionally, we synthesize semiconducting organic cations and integrate them into 2D chiral halide perovskites to tune the band structure and charge transport. To reveal the origin of the chirality, we conduct density functional theory calculations to gain the insights of hydrogen bonding and octahedral structure as well as their relationship to the electronic band structure and spin spilt. We perform temperature dependent powder X-ray diffraction and pair distribution function measurements to investigate structural variations with temperature to help understanding the observation of the unique behavior exhibited in the temperature dependent circularly polarized photoluminescent measurements. We construct photodiode-typed CPL photodetectors and demonstrate a record high distinguishability of right-handed and left-handed circularly polarized light. While many phenomena are unknown and needed further investigations, our work provides a new way to manipulate chirality of 2D perovskites, which could lead to broader applications.

Bio:
Qiuming Yu received her B.S. and M.S. in Chemistry from Nanjing University, China in 1985 and 1989, respectively, and her Ph.D. in Chemical Engineering from Cornell University in 1995. She was a postdoctoral fellow in the Micro-devices Laboratory at the NASA Jet Propulsion Laboratory, California Institute of Technology, from 1995-1996. After spending three years as a research assistant professor in Chemical Engineering at Kansas State University, she moved to the University of Washington and was a full professor in the Department of Chemical Engineering. She joined the Robert Frederick Smith School of Chemical and Biomolecular Engineering at Cornell University in July 2020 as a professor.