电子科学与技术学院2017年学术报告会之五-Probing Light-Matter Interactions in Perovskite Crystals
来源：电子科学与技术学院 浏览：101 时间：2017-04-05
题 目：Probing Light-Matter Interactions in Perovskite Crystals
报告人：Qihua Xiong, Ph.D. Professor of Physics and Electrical Engineering Fellow, Singapore National Research Foundation，School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore
The interaction of light with matter gives rises to a wide range of phenomena that we are familiar with, such as absorption, scattering, and spontaneous or stimulated emission. The electromagnetic field of light polarizes the matter that is responsible for many linear or nonlinear optical processes, which lay down the foundation of a wide range of photonic and optoelectronic devices that have modernized our life and society. In this talk, I will first introduce our capability of probing light-matter interactions in nanoscale semiconductor materials, whereby the quantum size and structure anisotropy play an important role. I will then discuss our effort in vapor phase synthesis of high quality inorganic-organic or all-inorganic perovskite crystals. Those crystals exhibit regularly hexagon or square facets with sufficiently large laser damaging threshold while the emission edge can be tuned from ultraviolet to near-infrared. Steady-state and transient spectroscopy approaches can elaborate the large exciton binding energy and excitonic emission nature at room temperature. Optically pumped photonic lasing based on the intrinsic whispering gallery mode cavity will then be presented, while the lasing quality factor can be as high as 5000 in all-inorganic perovskite crystals. Lastly, I will present our recent experimental realization of room-temperature polariton lasing in all-inorganic cesium lead chloride perovskite crystals embedded in two distributed Bragg reflectors. The perovskite crystals possess efficient polariton-polariton scattering due to the Wannier-Mott exciton nature with large binding energy. The polariton lasing is evidenced by a superlinear power dependence, macroscopic ground state occupation, and increase of the temporal coherence. Our work advocates the considerable promise of perovskite materials for photonics and nanophotonics applications.
Qihua Xiong received his B.S. degree in physics from Wuhan University in 1997, and then finished three years graduate studies at the Shanghai Institute of Applied Physics, Chinese Academy of Sciences. He went to the United States in 2000 and received Ph.D. degree under the supervision of Prof. Peter C. Eklund from The Pennsylvania State University in 2006. After three years postdoctoral experience in Prof. Charles M. Lieber’s group at Harvard University, he joined Nanyang Technological University as an assistant professor in 2009 and promoted to Nanyang Associate Professor in 2014. He was promoted to full Professor in 2016 recently. He is a Fellow of Singapore National Research Foundation awarded in 2009 and the inaugural NRF Investigatorship Award by Singapore National Research Foundation. He is the recipient of IPS Nanotechnology Physics Award (2015) and Nanyang Award for Research Excellence of NTU (2014). Prof. Xiong’s research focuses on light-matter interactions of emergent quantum matter by optical spectroscopy approaches. He recently ventured into the field of 2D layered materials and laser cooling of solids.