In-Situ Epitaxial Growth of MAPbBr3 /MAPbCl3 Lateral Heterojunction Single Crystal Films for High Performance Photo-detectors

Abstract

This study demonstrates the in-situ construction of a MAPbBr 3 /MAPbCl 3 heterojunction single crystal films (SCF) via a space confined epitaxial growth technique to address the critical issues of defects and interface states in perovskite optoelectronics. By leveraging the type-II band alignment and a low lattice mismatch of ~4.2% between MAPbBr 3 and MAPbCl 3 , the heterostructure facilitates effective interfacial charge separation and suppresses non-radiative recombination.Characterizations confirm the high crystalline quality and minimal ion exchange at the heterointerface. The resultant planar photo-detector exhibits significantly suppressed dark current (~10 -12 A), a high on/off ratio of 1.8×10 3 , and enhanced responsivity (2.8 mA/W) and specific detectivity (2.8×10 11 Jones) under 445 nm illumination at a bias of 0.01 V. This work provides a feasible epitaxial strategy for high-performance perovskite heterojunction devices through effective interface engineering.