Dramatically Enhanced Photoluminescence from Femtosecond Laser Induced Micro‐/Nanostructures on MAPbBr₃ Single Crystal Surface

Abstract Single crystal perovskites are used in solar cells, photodetectors, and other devices due to their excellent light absorption and carrier transport characteristics. However, for light‐emitting applications, photoluminescence (PL) is usually weak for MAPbBr₃ (MA = CH₃NH₃⁺) single crystals (MBSCs) compared with their polycrystalline counterpart. Therefore, developing novel techniques to process MBSCs with different morphologies for PL‐related applications is greatly needed. The current strategies for making perovskite crystals are mostly based on bottom‐up method (chemical synthesis and assembling). Here, an easy method to achieve top‐down fabrication of MBSCs, i.e., femtosecond laser processing MBSC surface by controlling the laser parameters is demonstrated. The femtosecond laser processing technology can achieve two orders of magnitude enhancement under ambient conditions in PL. In addition, the processed regions also show three times enhancement in PL under nitrogen environment. It is assumed that this is mainly due to the texture based on photon recycling and light out‐coupling mechanism, and the passivation of surface recombination centers on MBSC. This study not only provides a convenient top‐down strategy to achieve a range of morphological micro‐/nanostructures with enhanced PL on MBSC surface, but also paves the way for applications of MBSCs in light emitting or PL imaging devices.