Control of symmetry breaking in organic-inorganic hybrid semiconductors

Bio: Lina Quan earned her Ph.D. in Chemistry from Ewha Womans University in Seoul, South Korea, where she conducted joint research with Prof. Edward Sargent at the University of Toronto. She went on to complete postdoctoral research at the University of Toronto and the University of California, Berkeley, working with Prof. Peidong Yang from 2018 to 2020. She began her independent career as an Assistant Professor at Virginia Tech from 2021 to 2025 and is currently an Assistant Professor in the Department of Chemistry at UNC Chapel Hill. Her research focuses on understanding the optical and electronic properties of emerging semiconductors, including halide perovskites and their derivatives, with the goal of advancing their applications in next-generation semiconductor and quantum technologies. She received the 2024 U.S. Department of Energy (DOE) Early Career Research Award and the 2025 National Science Foundation (NSF) CAREER Award. She is also a Scialog Fellow in Negative Emissions Science and has been recognized as a Clarivate Highly Cited Researcher annually since 2019.

Abstract: Organic–inorganic hybrid semiconductors provide a versatile platform in which the structural tunability of molecular components can be coupled with the exceptional electronic and optical properties of an inorganic lattice. A particularly powerful aspect of these materials is the ability to manipulate symmetry breaking across multiple length and time scales, creating new opportunities to control light–matter interactions, spin dynamics, and functional excited states. In this seminar, I will discuss our efforts to understand and control symmetry breaking in metal halide hybrid semiconductors through molecular design, compositional engineering, and light–matter interactions. First, I will describe how optical excitation can drive hybrid metal halides into long-lived, metastable polar states, revealing a pathway to dynamically generate broken-symmetry structures that are inaccessible under equilibrium conditions. The coupling between photoexcitation, lattice distortion, and structural dynamics provides new opportunities for controlling nonlinear optical responses and persistent material functionalities. I will then discuss how chiral organic–inorganic perovskites provide a molecular approach to controlling inversion symmetry and spin-dependent photophysics. Using ultrafast, spin-resolved spectroscopy, we investigate how structural chirality and spin–orbit coupling govern carrier spin polarization and relaxation. In particular, compositional engineering through mixed organic cations provides an additional degree of freedom for tuning local lattice distortion, electronic structure, and spin dynamics beyond what is accessible in single-cation materials.