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

Abstract

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 MAPbBr₃ SCF and selected BA₂PbI₄ 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 cm² V⁻¹ s⁻¹, and the surface defect density is reduced to 3.4 × 10¹² cm⁻³. Therefore, the self-driven vertical MAPbBr₃ SCF photodetector after surface passivation exhibits more excellent optoelectronic performance.