Electron-phonon Interaction and Fröhlich Polaron Diffusion of Ferroelectric Perovskite Materials

In 2009, methylammonium lead perovskite was introduced as a light-absorbing material for solar cells, and solar cells based on this material achieved an astonishing conversion efficiency improvement of 25% in 2020. It has been pointed out that the diffusion distance of photogenerated carriers (electrons and holes) is extremely long compared to that of conventional semiconductor inorganic materials as a factor for the high efficiency, but the mechanism of carrier recombination suppression remains unclear. In this study, based on first-principles calculations of carrier-phonon interactions in ferroelectric perovskite materials, we discuss the mechanism of carrier recombination suppression in terms of Fröhlich polaron formation due to the interaction between photogenerated carriers and longitudinal optical phonons.