Tunable photostriction of halide perovskites through energy dependent photoexcitation
Bo Peng, Daniel Bennett, Ivona Bravić, Bartomeu Monserrat
Abstract
Photostriction, the name given to volume changes upon illumination, has recently been observed in halide perovskites. However, the microscopic mechanism remains unclear. In this letter, the authors propose that the orbital character of the electronic bands near the Fermi level determine the photostriction behavior. They find that photoexciting electrons from strong antibonding valence states to weaker antibonding conduction states leads to lattice contraction as a result of weakened antibonding interaction. Interestingly, using higher excitation energies promotes electrons from deeper nonbonding valence states to antibonding conduction states, resulting in giant lattice expansion. These results rationalize the experimentally observed tunable photostriction in halide perovskites.