Spatiotemporal Dynamics of Photo-excited Electrons and Holes in Organometal Trihalide Perovskites by Microwave Impedance Microscopy

ORAL

Abstract

The outstanding performance of organometal trihalide solar cells benefits from the exceptional photo-physical properties of both electrons and holes in the material. Here, we directly probe the spatial diffusion and temporal dynamics of photo-generated free carriers in Cs-doped FAPbI3 thin films by nanoscale microwave impedance microscopy. The sample exhibits two relaxation times on the order of 1 μs and 10 μs, which are uniform across grains and grain boundaries. Using charge transport layers to selectively quench one type of carriers, we are able to attribute the short and long lifetimes to that of electrons and holes, respectively. Both types of carriers display a long diffusion length of 3 ~ 5 μm, indicating that the difference in lifetimes is compensated by their distinct mobility. The spatiotemporal microwave imaging provides the most direct method to accurately determine photo-physical properties, which are crucial for the development of perovskite solar cells.

*NSF MRSEC under DMR-1720595
Welch Foundation Grant F-1814 and F-1662.
US Army Research Laboratory and the US Army Research Office under Grants W911NF-16-1-0276 and W911NF-17-1-0190.
U.S. DOE under Contract No. DE-AC36-08GO28308 with Alliance for Sustainable Energy, Limited Liability Company (LLC)

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Presenters

  • Xuejian Ma

    • Department of Physics, University of Texas at Austin

Authors

  • Xuejian Ma

    • Department of Physics, University of Texas at Austin

  • Fei Zhang

    • Chemistry and Nanoscience Center, National Renewable Energy Laboratory

  • Zhaodong Chu

    • Department of Physics, University of Texas at Austin

  • Ji Hao

    • National Renewable Energy Laboratory
    • Chemistry and Nanoscience Center, National Renewable Energy Laboratory

  • Xihan Chen

    • Chemistry and Nanoscience Center, National Renewable Energy Laboratory

  • Jiamin Quan

    • Department of Physics, University of Texas at Austin

  • Xiaoqin (Elaine) Li

    • University of Texas at Austin
    • Physics, University of Texas at Austin
    • Department of Physics, University of Texas at Austin
    • U.T. Austin
    • Department of Physics, The University of Texas at Austin
    • Department of Physics, Center of Complex Quantum Systems, University of Texas at Austin

  • Kai Zhu

    • Chemistry and Nanoscience Center, National Renewable Energy Laboratory

  • Keji Lai

    • University of Texas at Austin
    • Department of Physics, University of Texas at Austin