关于举行美国加州大学圣塔克鲁兹分校Jin Zhong Zhang教授学术报告会的通知
关于举行美国加州大学圣塔克鲁兹分校Jin Zhong Zhang教授学术报告会的通知
报告题目：Novel properties of nanostructured metal halide perovskites: beyond quantum dots and towards magic sized clusters and molecular clusters
报 告 人：Jin Zhong Zhang (张金中)教授（University of California Santa Cruz, U.S.A）
邀 请 人：夏志国 教授
报告时间：2023年5月30日（周二）下午15:00-17:00
报告地点： 北区科技园1号楼发光国重502会议室
报告摘要：
Metal halide perovskites (MHPs) with ABX3 structure, such as CH3NH3PbI3 and CsPbBr3, exhibit novel electronic, optical and magnetic properties that are promising for various applications including photovoltaics, LED, sensing, and quantum information technology. However, instability due to factors such as UV light, water, oxygen, and temperature limits their applications. The surface of the perovskites strongly affects stability, especially in terms of environmental factors such as solvent and oxygen. We have developed different surface passivation strategies to stabilize perovskite quantum dots (PQDs) and bulk films using surface chemistry approaches based on molecular ligands. The detailed molecular structures of the ligands make a major difference in their effectiveness of passivation for PQDs vs bulk films, e.g. steric hindrance between ligand molecules. Another important finding is that ammonium ions (-NH3+) and carboxylate groups (-COO-) have synergistic effects in surface passivation, attributed to simultaneous passivation of both anions (X-) and cations (Pb2+ or CH3NH3+) on the surface. In addition, we have developed conjugated ligands to improve charge delocalization and transfer/transport, as well as phosphonic ligands that are highly effective for passivation. This is particularly important for creating QD solids important for devices applications. In general, we found a “cocktail” approach using a combination of ligands to be most effective in passivating the multiple surface defects. More recently, we have found a simple strategy to synthesize and stabilize magic sized clusters (MSCs) of MHPs with strong quantum confinement (SQC), including doping, that exhibit interesting optical properties potential important for use as unique quantum materials for data storage and single photon emitting applications. In our efforts to understand the growth mechanism of MSCs, we discovered a new species that we call molecular cluster (MCs) that do not contain the A component of the perovskites and can be stabilized in solid form of interest for applications. In all, our studies demonstrate that surface chemistry approaches are promising for stabilizing MHPs, leading to generation of doped and undoped PQDs, MSCs and MCs, which is significant for many emerging applications.
报告人简介：
Jin Z. Zhang received his B.Sc. degree in Chemistry from Fudan University, Shanghai, China, in 1983 and his Ph.D. in physical chemistry from University of Washington, Seattle in 1989. He was a postdoctoral research fellow at University of California Berkeley from 1989 to 1992. In 1992, he joined the faculty at UC Santa Cruz, where he is currently distinguished professor of chemistry and biochemistry. Zhang’s recent research interests focus on design, synthesis, characterization, and exploration of applications of advanced materials including semiconductor, metal, and metal oxide nanomaterials, particularly in the areas of solar energy conversion, solid state lighting, sensing, and biomedical detection/therapy. He has authored over 400 publications and four books. Zhang is currently executive editor for JPCL and associate editor of ACS Physical Chemistry Au published by ACS. He is a Fellow of AAAS, APS, RSC, and ACS. He is the recipient of the 2014 Richard A. Glenn Award of the ACS Energy and Fuel Division.
