2020-08-012024-05-17https://scholars.lib.ntu.edu.tw/handle/123456789/680565The organic-inorganic halide perovskites have shown a remarkable photovoltaics in solar cell performance, surpassing previously the top efficiency achieved with conventional silicon-based solar cells. In addition, due to the preparation via simple and low-cost solution processes, organic-inorganic halide perovskites demonstrate the immense potential alternative to the future commercially photovoltaic technologies. Many theoretical reports predicted that the orientation of the organic molecules plays a fundamental role in determining the perovskite-based optoelectronic properties. However, experimentally, to directly explore the microscopic origin about the underlying photophysics involving photon-lattice coupling and the role played by the organic molecules in the light-illuminating process still remains poorly understood. Scanning tunneling microscopy and spectroscopy (STM/S) could be presently the only approachable technique to investigate the organic molecule-related issues in halide perovskites. Thus, in this proposal, we intend to improve the present capability of the cross-sectional STM technique in our lab with the light-modulated function and the externally electric availability to mimic the real perovskite-based operation conditions. With the advances of the cross-sectional STM/S technique, the latest cutting-edge problems with atomic resolution involving the role of organic molecules in halide perovskites can be revealed. In this project, several organic molecule-related problems regarding compositional engineering, mixed dimensions (two-dimensional mixed three-dimensional, 2D/3D), and all-inorganic perovskite materials will be studied. In addition, experimentally, utilizing the light-modulated XSTM/S technique, the simultaneous molecule dipole orientation pattern and the electrostatic potential with atomic resolution under light illumination or under an externally applied electric field can be directly mapped. We identify and work on the exploration of the microscopic origin of the halide perovskites in this project. With the atomically-resolved XSTM results, the challenging organic molecules-related problems in halide perovskites will be discussed. In addition, to mimic the real device operation conditions, the atomically-resolved XSTM measurements can be performed under light-modulated situations and an externally electric availability. We expect to provide the direct observations for developing a comprehensive physical understanding of charge carrier dynamics and high photovoltaic performance in halide perovskites under actual operation conditions.cross-sectional STM; organic-inorganic halide perovskites; light-modulated functions; externally electric availability; molecule dipole orientation