A fractional crystallization technique towards pure mega-size CsPb2Br5 single crystal films

A facile fractional crystallization technique was developed to prepare single crystalline CsPb2Br5 films using water as the solvent, and the films can be easily transferred onto various substrates for the device fabrication. The obtained films can be up to 600 × 600 μm2 and decrease to 50 nm in thickness with high crystalline quality as well as temperature and air stability.