Lattice Anharmonicity: A Double-Edged Sword for 3D Perovskite-Based Optoelectronics

Halide perovskites have attracted much attention due to their remarkable optoelectronic properties, such as long carrier lifetimes and diffusion lengths. However, current state-of-the-art perovskite optoelectronics lack long-term stability and are prone to ion or defect migration. In this Perspective, we discuss the structural properties and dynamics of the perovskite lattice that extend carrier lifetimes, but that also may facilitate ion migration. We describe changes of the vibrational properties of the anharmonic perovskite lattice in both the ground and excited electronic states and reveal the influence that these changes have on carrier recombination and ion transport under the influence of optical and electrical excitation. Finally, we suggest modifications of the phonon dynamics of the perovskite lattice that may allow these properties of the materials to be tuned to strike the right balance between carrier dynamics and ion migration.