報告題目：Novel Properties of Organo-metal Halide
Perovskites: From Magic Sized Clusters to Quantum
Dots and Quantum Dot Solids
报 告 人：Jin Zhong Zhang （張金中）教授（美國加州大學聖克魯茲分校）
Organo-metal halide perovskites (OMHP), such as CH3NH3PbI3, and all inorganic metal halide perovskites (IMHPs) 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. This is supported by our demonstration that bifunctional peptide-like molecules are highly effective as bidentate ligands for surface passivation. 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.
Very recently, we have found a simple strategy to synthesize and stabilize magic sized clusters (MSCs) of both OMHP and IMHP that exhibit interesting optical properties potential important for use as unique quantum materials for data storage and single photon emitting applications. In all, our studies demonstrate that surface chemistry approaches are promising for stabilizing OMHP or IMHP, leading to generation of MSCs, QDs, and QD solids, which is significant for many emerging applications.
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 full 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 340 publications and three books. Zhang has been serving as a senior editor for JPC(L) published by ACS since 2004. He is a Fellow of AAAS, APS, and ACS. He is the recipient of the 2014 Richard A. Glenn Award of the ACS Energy and Fuel Division.
现主要从事半导体、金属、纳米金属氧化物等先进材料的设计、合成、表征和应用开发，研究专注于太阳能转化，固体材料发光技术和生物医学检测、治疗方面的应用研究。已发表研究论文340余篇，出版著作3部。担任Journal of Physical Chemistry Letters副主编，American Association for the Advancement of Science，American Physical Society和American Chemical Society会士。他是2014 ACS Energy and Fuel Division Richard A. Glenn奖的获得者。