In-situ passivating surface defects of ultra-thin MAPbBr3 perovskite single crystal films for high performance photodetectors

Ultra-thin single crystal film (SCF) without grain boundary inherits low charge recombination probability as bulk single crystals. However, its low depth brings a high surface defect ratio and hinders the carrier transport and extraction, which affects the performance and stability of optoelectronic devices such as photodetectors, and thus surface defect passivation is of great practical significance. In this paper, we use the space confined method to grow MAPbBr 3 SCF and selected BA 2 PbI 4 for surface defect passivation. The results reveal that BA cation passivates MA vacancy surface defects, reduces carrier recombination, and enhances carrier lifetime. The carrier mobility is as high as 33.6 cm 2 V −1 s −1 , and the surface defect density is reduced to 3.4 × 10 12 cm −3 . Therefore, the self-driven vertical MAPbBr 3 SCF photodetector after surface passivation exhibits more excellent optoelectronic performance. BA 2 PbI 4 is selected to passivate the surface defects of MAPbBr 3 SCFs. The addition of BA interacts with MA vacancy through chemical bonding, thus reducing surface defect density to achieve high performance photo-detector.