Carnegie Institution for Science, Washington, D.C.
12 PM, Wednesday, February 22nd, 2017
1065 Kemper Hall
Abstract: The discovery and application of multifunctional materials such as ferroelectrics have led to paradigm shifts in technologies. Ferroelectrics characterized by the switchable polarization have become pervasive in modern devices, which heavily rely on the interactions between the polarization and applied stimuli. Understanding the dynamical response of ferroelectrics is crucial for the accelerated materials discovery and the development of novel engineering strategies for optimized and breakthrough applications of ferroelectrics. The ferroelectric switching process often spans multiple scales in time and space, making it challenging to establish clear predictive relationships between microscopic quantities and macroscopic performance. In this talk, I will cover a multiscale computational approach that combines methods at different length and time scales to elucidate the connection between local structures, domain wall motions, and dynamical properties of ferroelectrics. I will also highlight how nanoscale polar domains play an important role in the carrier dynamics in the solar materials represented by organic-inorganic hybrid perovskites and how atomistic simulations enable atomic-level mechanistic understandings of various functional properties of hybrid perovskites such as long carrier lifetime and diffusion length.
Biography: Shi Liu graduated in 2009 from the University of Science and Technology of China with a B.S. in chemical physics, before completing his Ph.D. in chemistry at the University of Pennsylvania in 2015. During the Ph.D. program, he worked under the direction of Professor Andrew M. Rappe, developing and applying predictive multiscale modeling techniques that combine methods at different length and time scales to understand the dynamics of ferroelectric materials from the atomistic level all the way up to the mesoscopic length scales. Dr. Liu’s research interests also involve free radical reactions in polymerization, topological insulators, and organic-inorganic hybrid perovskites. He was awarded the 2015 Professor John G. Miller Award for the Best Thesis in Penn Chemistry. Following completion of his Ph.D., Dr. Liu was offered a Carnegie Fellowship at the Carnegie Institution for Science in Washington, D.C., where he is currently working with Dr. Ronald E. Cohen on multiscale simulations of defects in ferroelectrics and hybrid perovskites for photovoltaic applications. He was recently awarded the American Physical Society 2017 Nicholas Metropolis Award for Outstanding Doctoral Thesis Work in Computational Physics.