High-pressure structural and optical property evolution of a hybrid indium halide perovskite

Reported is the high-pressure structural and optical characterization of a chloroindium(III) hybrid perovskite consisting of isolated anionic [In2Cl10]4- dimers charge balanced by 4-iodopyridinium cations. No phase transitions were observed upon compression between 0 and 1.51 ​GPa. The metal-halide bond lengths of the dimers decrease slightly, resulting in reduced octahedral distortion of the InCl6 building blocks. The main mechanism of compression is between the anions and cations. Computational density functional theory (DFT) based natural bonding orbital (NBO) and density of state (DOS) methods were utilized to (i) map the band structure, (ii) quantify and categorize noncovalent interaction strength and type, and (iii) deconstruct metal-halide bonding orbitals. Findings reveal the appearance of a pressure induced hybridized molecular orbital containing both In3+ and Cl p-states, and slight enhancement of bridging In–Cl bonding as indicated by increased In3+ orbital character.