Pressure effects on the structures and electronic properties of halide perovskite CsPbX3 (X = I, Br, Cl)

Two monoclinic C2/m phases and an insulator–metal transition were discovered in CsPbI₃ at high pressure. Furthermore, the largest piezochromic effect in the perovskites occurs in the non-Pv-Pnma phase of CsPbI₃ below 10 GPa.