Growth, characterization and optoelectronic applications of pure-phase large-area CsPb2Br5 flake single crystals

Abstract

To clarify the controversies on CsPb₂Br₅ and extend its optoelectronic applications, from a thermodynamic equilibrium growth system, pure phase high quality CsPb₂Br₅ single crystals (maximum area: 5 × 5 mm², minimum thickness: 160 nm) were successfully obtained. Optical characterization results indicated a 3.87 eV bandgap for CsPb₂Br₅, clarifying the controversies on CsPb₂Br₅. The fabricated photodetector showed a sensitive and fast deep-UV photoresponse, demonstrating the potential applications of CsPb₂Br₅ in deep-UV detection. Theoretical calculations suggested that the wide bandgap of CsPb₂Br₅ resulted from its layered structure and short Pb–Br bonds.