Polaronic Charge Carrier-Lattice Interactions in Lead Halide Perovskites

Almost ten years after the renaissance of the popular perovskite-type semiconductors based on lead salts with the general formula AMX(3) (A=organic or inorganic cation; M=divalent metal; X=halide), many facets of photophysics continue to puzzle researchers. In this Minireview, light is shed on the low mobilities of charge carriers in lead halide perovskites with special focus on the lattice properties at non-zero temperature. The polar and soft lattice leads to pronounced electron-phonon coupling, limiting carrier mobility and retarding recombination. We propose that the proper picture of excited charge carriers at temperature ranges that are relevant for device operations is that of a polaron, with Frohlich coupling constants between 1<a