CsPb2 Br5 Single Crystals: Synthesis and Characterization.

CsPb2 Br5 is a ternary halogen-plumbate material with close characteristics to the well-reported halide perovskites. Owing to its unconventional two-dimensional structure, CsPb2 Br5 is being looked at broadly for potential applications in optoelectronics. CsPb2 Br5 investigations are currently limited to nanostructures and powder forms of the material, which present unclear and conflicting optical properties. In this study, we present the synthesis and characterization of CsPb2 Br5 bulk single crystals, which enabled us to finally clarify the material's optical features. Our CsPb2 Br5 crystal has a two-dimensional structure with Pb2 Br5- layers spaced by Cs+ cations, and exhibits approximately 3.1 eV indirect band gap with no emission in the visible spectrum.