CrystEngComm

Organic–inorganic hybrid perovskite materials have been receiving considerable attention due to their promising applications in many optoelectronic fields. However, some of the fundamental properties of perovskite materials are still disputed, because most of them are derived from a thin-film state. To comprehend the intrinsic characteristics in a single crystal, herein we report, for the first time, the bulk crystal growth of CH₃NH₃PbI₃. Single crystals of tetragonal CH₃NH₃PbI₃ with dimensions of 10 mm × 10 mm × 8 mm were grown by a temperature-lowering method in HI solution. Studies in to the refinement and orientations of the CH₃NH₃PbI₃ single crystal structure were conducted based on a high quality crystal. The absorption edge of a CH₃NH₃PbI₃ single crystal was located at about 836 nm, indicating that the band gap of CH₃NH₃PbI₃ is approximately 1.48 eV, which is close to the theoretical results and smaller than those derived from polycrystalline and thin-films. CH₃NH₃PbI₃ crystal exhibits a relatively wide absorption (from 250 nm to 800 nm) and a relatively good thermal stability.