Single-Crystal Thin Films of Cesium Lead Bromide Perovskite Epitaxially Grown on Metal Oxide Perovskite (SrTiO3).

High-quality metal halide perovskite single crystals have low defect densities and excellent photophysical properties, yet thin films are the most sought after material geometry for optoelectronic devices. Perovskite single-crystal thin films (SCTFs) would be highly desirable for high-performance devices, but their growth remains challenging, particularly for inorganic metal halide perovskites. Herein, we report the facile vapor-phase epitaxial growth of cesium lead bromide perovskite (CsPbBr3) continuous SCTFs with controllable micrometer thickness, as well as nanoplate arrays, on traditional oxide perovskite SrTiO3(100) substrates. Heteroepitaxial single-crystal growth is enabled by the serendipitous incommensurate lattice match between these two perovskites, and overcoming the limitation of island-forming Volmer-Weber crystal growth is critical for growing large-area continuous thin films. Time-resolved photoluminescence, transient reflection spectroscopy, and electrical transport measurements show that the CsPbBr3 epitaxial thin film has a slow charge carrier recombination rate, low surface recombination velocity (104 cm s-1), and low defect density of 1012 cm-3, which are comparable to those of CsPbBr3 single crystals. This work suggests a general approach using oxide perovskites as substrates for heteroepitaxial growth of halide perovskites. The high-quality halide perovskite SCTFs epitaxially integrated with multifunctional oxide perovskites could open up opportunities for a variety of high-performance optoelectronics devices.