Polaron Masses in CH₃NH₃PbX₃ Perovskites Determined by Landau Level Spectroscopy in Low Magnetic Fields

Abstract

We investigate the electron-phonon coupling in CH₃NH₃PbX₃ lead halide perovskites through the observation of Landau levels and high-order excitons at weak magnetic fields, where the cyclotron energy is significantly smaller than the longitudinal optical phonon energy. The reduced masses of the carriers and the exciton binding energies obtained from these data are clearly influenced by polaron formation. We analyze the field-dependent polaronic and excitonic properties, and show that they can be quantitatively reproduced by the Fröhlich large polaron model.