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

To clarify the controversies on CsPb2Br5 and extend its opto-electronic applications, from a thermodynamic equilibrium growth system, pure phase high quality CsPb2Br5 single crystals (maximum area: 5 x 5 mm(2), 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.