Shape and phase evolution from CsPbBr3 perovskite nanocubes to tetragonal CsPb2Br5 nanosheets with an indirect bandgap

Tetragonal CsPb2Br5 nanosheets were obtained by an oriented attachment of orthorhombic CsPbBr3 nanocubes, involving a lateral shape evolution from octagonal to square. Meanwhile, the experimental results, together with DFT simulation results, indicated that the tetragonal CsPb2Br5 is an indirect bandgap semiconductor that is PL-inactive with a bandgap of 2.979 eV.