Nanoscale investigations by scanning probe microscopy have provided major contributions to the rapid development of organic-inorganic halide perovskites (OIHP) as optoelectronic devices. Further improvement of device level properties requires a deeper understanding of the performance-limiting mechanisms such as ion migration, phase segregation and their effects on charge extraction both at the nano- and macroscale. Here, we have studied the dynamic electrical response of Cs0.05(FA0.83-MA0.17)0.95PbI3-xBrx perovskite structures by employing conventional and microsecond time-resolved Kelvin probe force microscopy (KPFM). Our results indicate strong negative charge carrier trapping upon illumination and very slow (>1s) relaxation of charges at the grain boundaries. The fast electronic recombination and transport dynamics on the microsecond scale probed by time-resolved KPFM show diffusion of charge carriers towards grain boundaries and indicate locally higher recombination rates due to intrinsic spatial heterogeneity. The nanoscale electrostatic effects revealed are summarized in a collective model for mixed-halide CsFAMA. Results on multilayer solar cell structures draw direct relations between nanoscale ionic transport, electron accumulation, recombination properties and the final device performance. Our findings extend the current understanding of complex charge carrier dynamics in stable multi-cation OIHP structures.
Comparison of Electroluminescence and Photoluminescence Imaging of Mixed-Cation Mixed-Halide Perovskite Solar Cells at Low Temperatures
National Institute of Standards & Technology（美国国家标准与技术研究院）；Department of Physics and Astronomy and Wright Center for Photovoltaics Innovation and Commercialization, The University of Toledo（托莱多大学物理与天文学系及光伏创新与商业化赖特中心）；Department of Electrical and Computer Engineering, Johns Hopkins University（约翰斯·霍普金斯大学电气与计算机工程系）；Department of Materials Science and Engineering, Johns Hopkins University（约翰斯·霍普金斯大学材料科学与工程系）
Enhanced Stability and Linearly Polarized Emission from CsPbI$_3$ Perovskite Nanoplatelets through A-site Cation Engineering
Sungkyunkwan University（成均馆大学）；University of Oxford（牛津大学）；Ulsan National Institute of Science and Technology (UNIST)（蔚山科学技术院）；Sun Yat-sen University（中山大学）
