Surface Reconstruction of Inorganic Perovskite by The Nanosecond Laser Pulse

While the organic-inorganic hybrid metal halide perovskite has recently achieved remarkable performance in photovoltaics, all-inorganic perovskite (CsPbI_3-xBr_x, X = 0~3) has been proposed as a stable alternative to their organic counterparts. The all-inorganic perovskite demonstrates robust thermal- and photo-stability owing to relatively high thermal decomposition temperature and high ion migration activation energy. Moreover, their suitable energy bandgap (&gt;1.65 eV) offers wide opportunities for applications such as single-junction photovoltaics, tandem solar cells, and indoor photovoltaics. However, inorganic perovskite suffers from rapid crystallization during the film fabrication process, resulting in morphological and surface electronic inhomogeneities. Such inhomogeneities act as charge recombination centers and deter efficient charge extraction, leading to poor reproducibility and performance.<br/>In this study, we implement a nanosecond pulsed laser as an effective tool to reconstruct the surface of inorganic perovskite films. The pulsed lasers are powerful instruments that provide rapid, accurate, and precise processes and are readily accessible as they are already widely adopted in industries. With careful control of the pulse energy, we were able to homogenize the surface potential of inorganic perovskite. In addition, we thoroughly characterize the impacts on the various perspectives including crystallinity, morphology, chemical features, optoelectronic properties, and device performance of the inorganic perovskite film. We believe our study on the inorganic perovskite-laser pulse interaction offers an insightful approach for optimizing inorganic perovskite solar cells and potentially any other applications involving pulsed laser processes.