1Department of Physics, Shanghai University, Shanghai 200444 2State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 3Department of Chemical Engineering, School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444 4STU & SIOM Joint Laboratory for Superintense Lasers and Applications, Shanghai 201210 5College of Precision Instrument and Opto-electronics Engineering, Institute of Laser and Opto-electronics, Tianjin University, Tianjin 300072
Abstract：Using time-dependent terahertz spectroscopy, we investigate the role of mixed-cation and mixed-halide on the ultrafast photoconductivity dynamics of two different methylammonium (MA) lead-iodide perovskite thin films. It is found that the dynamics of conductivity after photoexcitation reveals significant correlation on the microscopy crystalline features of the samples. Our results show that mixed-cation and lead mixed-halide affect the charge carrier dynamics of the lead-iodide perovskites. In the (5-AVA)$_{0.05}$(MA)$_{0.95}$PbI$_{2.95}$Cl$_{0.05}$/spiro thin film, we observe a much weaker saturation trend of the initial photoconductivity with high excitation fluence, which is attributed to the combined effect of sequential charge carrier generation, transfer, cooling and polaron formation.
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2019, Vol. 36 
