Epitaxial Growth of Large‐Scale Orthorhombic CsPbBr₃ Perovskite Thin Films with Anisotropic Photoresponse Property

Abstract

Abstract Inorganic cesium lead halide perovskite (CsPbX 3 , X = Cl, Br, I) is a promising material for developing novel electronic and optoelectronic devices. Despite the substantial progress that has been made in the development of large perovskite single crystals, the fabrication of high‐quality 2D perovskite single‐crystal films, especially perovskite with a low symmetry, still remains a challenge. Herein, large‐scale orthorhombic CsPbBr 3 single‐crystal thin films on zinc‐blende ZnSe crystals are synthesized via vapor‐phase epitaxy. Structural characterizations reveal a “CsPbBr 3 (110)//ZnSe(100), CsPbBr 3 [−110]//ZnSe[001] and CsPbBr 3 [001]//ZnSe[010]” heteroepitaxial relationship between the covering CsPbBr 3 layer and the ZnSe growth substrate. It is exciting that the epitaxial film presents an in‐plane anisotropic absorption property from 350 to 535 nm and polarization‐dependent photoluminescence. Photodetectors based on the epitaxial film exhibit a high photoresponsivity of 200 A W −1 , a large on/off current ratio exceeding 10 4 , a fast photoresponse time of about 20 ms, and good repeatability at room temperature. Importantly, a strong polarization‐dependent photoresponse is also found on the device fabricated using the epitaxial CsPbBr 3 film, making the orthorhombic perovskite promising building blocks for optoelectronic devices featured with anisotropy.