Pressure induced band structure evolution of halide perovskites: a first-principles atomic and electronic structure study

Density functional theory (DFT) based calculations have been conducted to draw a broad picture of pressure induced band structure evolution in various phases of organic and inorganic halide perovskite materials. Under a wide range of pressure applied, distinct band structure behaviors including magnitude change of band gap, direct-indirect/indirect-direct band gap transitions and CBM/VBM shifts, have been observed between organic and inorganic perovskites among different phases. Through atomic and electronic structure calculations, band gap narrowing/widening has been rationalized through crystal orbitals coupling transformations; direct-indirect mutual transitions were explained based on structural symmetry evolution; different VBM/CBM shifts behaviors between organic and inorganic perovskites were analyzed focusing on orientation and polarity of molecules/atoms outside the octahedrals. These results provide a comprehensive guidance for further experimental investigations on pressure engineering of perovskite materials.