Controllable Perovskite Single Crystal Heterojunction for Stable Self-Powered Photo-Imaging and X-Ray Detection

摘要

Semiconductor heterostructures underpin the design and performanceof virtually all modern optoelectronic systems. The clear interface, highcrystalline quality, and suitable energy band match lay the foundation forhigh-performance heterojunction optoelectronic devices. Here, a facilesolution epitaxial growth method is demonstrated for controllably growingCH_3NH_3PbBr_3 single crystal (SC) on the CH_3NH_3PbCl_3 SC, which forms a pnheterojunction with a well-defined interface and high single-crystalline quality.The thickness of the epitaxial layer can be finely controlled by adjustingthe growth time. Benefiting from excellent built-in electrical potential at pnheterojunction, the heterojunction detector shows an obvious rectificationbehavior and high performance in photo-imaging and X-ray detection withoutany power supply, including high responsivity (26.8 mA W~(?1)), fast responsetime (8/613 μs), and high sensitivity of 868 μC Gy_(air)~(?1) cm~(?2) with a recordlowest detectable X-ray dose rate of 15.5 nGy_(air) s~(?1). Furthermore, it exhibitshigh-fidelity UV photo-imaging capability at zero bias voltage. In addition,the heterojunction detector shows excellent stability by maintaining 99%of the initial responsivity after 120 days without any encapsulation inthe atmosphere. This work enables a significant advance in engineeringperovskite SC heterojunction for developing novel and functional devices.