Asymmetrical Photodetection Response of Methylammonium Lead Bromide Perovskite Single Crystal

Abstract

Abstract Because of their low trap densities and remarkable carrier transport properties, organic‐inorganic hybrid perovskite single crystals have been used as active materials in photodetectors to provide high photodetection responses. While the ideal methylammonium lead bromide (MAPbBr 3 ) perovskite has a cubic crystal structure, the structures and carrier transport properties of the actual crystals may have low symmetry as a result of low‐temperature fabrication processes used. In this work, the variable temperature crystallization method was proposed to fabricate large MAPbBr 3 single crystals. The unsymmetrical structures of the MAPbBr 3 single crystals were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The electrical properties and photodetection responses of these MAPbBr 3 single crystals along the different axial directions were then investigated. The asymmetrical trap density, the carrier mobility, and the photocurrent gain were all estimated from the measurement results. The best photodetection response was obtained along the vertical channel located between the top and bottom faces of the MAPbBr 3 single crystal. The photocurrent gain was 900, and the fall time for transient photodetection was 30 μs. The work presented here is expected to provide useful design information for photodetectors based on perovskite single crystals.