In situ epitaxial growth of MAPbBr3/MAPbCl3 lateral heterojunction single-crystal films for high-performance photodetectors

Abstract

This study demonstrates the in situ construction of a MAPbBr₃/MAPbCl₃ heterojunction single-crystal film (SCF) via a space-confined epitaxial growth technique to address the critical issues of defects and interfacial states in perovskite optoelectronics. By leveraging the type-II band alignment and a low lattice mismatch of ∼4.2% between MAPbBr₃ and MAPbCl₃, the heterostructure facilitates effective interfacial charge separation and suppresses non-radiative recombination. Characterization confirms the high crystalline quality and minimal ion exchange at the heterointerface. The resultant planar photodetector exhibits a significantly suppressed dark current (∼10⁻¹² A), a high on/off ratio of 1.8 × 10³, and enhanced responsivity (2.8 mA W⁻¹) and specific detectivity (2.8 × 10¹¹ 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.