Origin of pressure-induced band gap tuning in tin halide perovskites

Structural and optical high-pressure study of FASnBr 3 revealed a cubic to orthorhombic phase transition near 1.4 GPa accompanied by a huge band gap red-shift from 2.4 to 1.6 eV, which is followed by a blue-shift of ∼0.2 eV upon further pressure increase.