Fig. 2: Structural of Cs3Bi2I9 PSC.

a Photographs of representative Cs3Bi2I9 PSCs. b Powder XRD patterns of the Cs3Bi2I9 PSC. c Single-crystal X-ray diffraction spots of a Cs3Bi2I9 PSC. d Configuration of 2 × 2 × 1 supercell Cs3Bi2I9. e XRD 2θ scan on the (002) facet of the Cs3Bi2I9 PSC. f, g High-resolution XRD rocking curves of the diffraction peaks at (002) and (004).