Light-modified Electronic Transition of Atomic Defect in Metalorganic Halide Perovskite Solar Cells
Hung-Chang Hsu1*, Huai-En Chen1, Ya-Ping Chiu1,2
1Department of physics, National Taiwan University, Taipei, Taiwan
2Center of Atomic Initiative for New Materials, National Taiwan University, Taipei, Taiwan
* Presenter:Hung-Chang Hsu,
Polaron formation due to electron-lattice coupling is an important mechanism to avoid carrier scattering in lead halide perovskite, which presents the high performance in solar cells. To demonstrate the electron-lattice coupling in atomic scale under photoelectronic operation, light-modulated cross-sectional scanning tunneling microscopy and spectroscopy (LM-XSTM/S) is utilized to observe the electronic transition on the orgnic-inorgamic terminal of MAPbBr₃ single crystal in dark and under illumination. The potential variation on the MA-Br defect site reveals that photoexcited carriers are injected to the exposed Pb atoms under illumination. Due to the softness of PbBr₃ octahedron, the spontaneous PbBr₃ deformation can directly screen the built-in coulomb potential on the defect site and reduce the photoexcited carrier scattering on the defect site. Polaron formation on the nature defect demonstrates the defect tolerance of halide perovskite solar cells under photoelectronic operation.

Keywords: organometal halide perovskites, scanning tunneling microscopy/spectroscopy, defect tolerance, polaron