题目：Ultrafast Time-resolved micro-spectroscopy for photophysics of organic-inorganic perovskites  

             超快时间分辨显微光谱技术用于有机无机钙钛矿太阳能电池的光物理研究

报告人：文小明博士

时间：12月7日（星期二）下午14：30

地点：动力与机械学院报告厅

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About the Lecturer

文小明博士，学士及硕士毕业于浙江大学。1989-2003在云南大学物理系任教，历任教授，副系主任。2007年在澳大利亚Swinburne University of Technology 获博士学位。后在澳大利亚墨尔本大学从事有机光伏材料的光物理研究，在台湾中央研究院从事纳米颗粒（半导体量子点，石墨烯量子点及金量子点）的光物理研究。2012-2016在世界著名的光伏学院Australian Centre for Advanced Photovoltaics, University of New South Wales (新南威尔士大学)从事太阳能材料与器件研究。与光伏之父马丁.格林教授合作进行钙钛矿太阳电池的研究，同时与多个研究组合作进行热载流子（hot carrier solar cells），CZTS 及量子点太阳电池等方向研究，担任高级研究员领导光物理方向研究。目前在澳大利亚斯文本科技大学Swinburne University of Technology从事新型太阳电池的研究。曾在悉尼大学（University of Sydney, Australia）和大阪电器通信大学(Osaka Electrocommunication University, Japan)从事合作研究。专业特长为超快/时间分辨光谱，单分子光谱，光伏/光催化材料的光学及显微表征，纳米材料中的电子/激子/声子动力学（碳纳米点/石墨稀量子点graphene QDs，金属量子点metallic nanoclusters， 半导体量子点等）。在澳大利亚和台湾分别组建多种先进超快光谱学实验。出版超快光谱学专著一部（独立作者），在国际知名的高影响因子刊物发表SCI论文一百多篇，如：Nature Communications, Nano Letters, Advanced Energy Materials, Advanced Materials, Journal of Physical Chemistry Letters等。担任Scientific Reports（Nature子刊）等学术杂志编辑，同时担任三十多个国际著名学术期刊的审稿人（Nature Communications，Advanced Materials, ACS Nano, Advanced Energy Materials, Nanoscale etc.）。

Abstract

Organic-inorganic hybrid perovskites have been shown very promising for next generation high efficiency low cost solution fabricated solar cells with quickly increased conversion efficiency over 22%. In addition, perovskites are promising candidate for photonic application, such as LED, light source, detector and sensors due to the high efficient luminescence. The device design and performance improvement critically depend on the physical understanding.

Ultrafast time-resolved spectroscopy and microscopy are very powerful tools to investigate photoexcited carrier dynamics and provide novel insight for designing and improving devices. Here I present the dynamics of charge carriers and mobile ions in organic-inorganic halide perovskite combining steady state, time-resolved spectroscopy and microscopy, in the various timescales from femtoseconds up to hours. In picosecond range, ultrafast transient absorption confirmed the slowed cooling of hot carriers in halide perovskites, which is promising for the next high efficiency hot carrier solar cells, with efficiency over the Shockley–Queisser limit. Recombination dynamics is investigated by nanoscale time-resolved photoluminescence. Our investigation reveals both steady state PL and time-resolved PL are closely relevant to the excitation intensity, which suggests that photogenerated excitons are effectively dissociated and free electron-hole recombination is the major mechanism. Moreover, mobile ions have significantly impact on the carrier dynamics. Mobile ion migration and accumulation result in a much slow process in milliseconds to hours, which is closely relevant to the characteristic hysteresis in I-V measurement and light soaking effects.

超快时间分辨光谱及显微技术已经成为一类有效的先进技术，广泛用于光伏，光催化及发光材料及器件的光物理和载流子动力学研究。这里简要介绍先进的超快时间分辨光谱及显微技术，以及应用于钙钛矿太阳能电池的光物理研究。揭示了光激活载流子，移动离子及其在钙钛矿材料系统中的相互作用。