Heteroepitaxy of Large-Area, Monocrystalline Lead Halide Perovskite Films on Gallium Arsenide.

Lead halide perovskite materials have been emerging as promising candidates for high-performance optoelectronic devices. Significant efforts have sought to realize monocrystalline perovskite films on a large scale. Here, we epitaxially grow monocrystalline methylammonium lead tribromide (MAPbBr 3 ) films on lattice-matched gallium arsenide (GaAs) substrates on a centimeter scale. In particular, a solution-processed lead(II) sulfide (PbS) layer provides a lattice-matched and chemical protective interface for the solid-gas reaction to form MAPbBr 3 films on GaAs. Structure characterizations identify the crystal orientations in the trilayer MAPbBr 3 /PbS/GaAs epistructure and confirm the monocrystalline nature of MAPbBr 3 on PbS/GaAs. The dynamic evolution of surface morphologies during the growth indicates a two-step epitaxial process. These fundamental understandings and practical growth techniques offer a viable guideline to approach high-quality perovskite films for previously inaccessible applications.