报告题目：Understanding Effects of Cesiumin CH(NH2)2PbI3 for Stabilizing CH(NH2)2PbI3/CsPbI3 Interface under UV Illumination
摘要：In solution-processed perovskite semiconductors (SPS’s), ultraviolet (UV) radiation can induce structural degradation in the light-absorbing layer, for instance methylammonium lead iodide (MAPbI3). In this paper, we use modulated surface photovoltage (SPV) spectroscopy to track the mechanisms of photo-generated charge generation and separation as well as the formation of defects in the formamidinium lead triiodide (FAPbI3) and cesium-containing (Cs) FAPbI3 (FAxCs1-xPbI3) perovskite when exposed to different durations of UV-light treatment. The measured SPV signals (in-phase and out-phase (shifted by 90o)) were found to be strongly dependent on the addition of Cs and on the UV exposure times. Upon the partial incorporation of Cs, the improved stability in the structural and optical properties was observed. The formation of the d-CsPbI3 phase in the FAxCs1-xPbI3 perovskite is attributed to the stabilization of the FAPbI3/CsPbI3 interface, which would efficiently inhibit the phase segregation, and provide for a stable medium for the modulated charge separation under UV illumination.
报告人简历：Thidarat Supasai received her PhD in Physics from the Faculty of Science, Chulalongkorn University, Thailand in 2012. She did her postdoctoral work at Helmholtz-Center Berlin for Materials and Energy, Germany in 2013-2014. Currently, she is an Assistant Professor and head of the laboratory of Nanomaterials for Photovoltaics at Department of Materials Science, Faculty of Science, Kasetsart University. Her current research interests include (i) fabrication of semiconducting materials for photovoltaics application (ii) characterization of photoactive materials by using surface photovoltage technique.