Absence of a giant Rashba effect in the valence band of lead halide perovskites

Abstract

The high efficiency of lead halide perovskite solar cells is revolutionizing photovoltaics and, at the same time, puzzling the scientific community. Here, the authors take up the prediction that a large Rashba-type spin-orbit effect slows down carrier recombination. From their experiments on organic perovskites, they conclude that this effect is much smaller than so far believed. For the inorganic CsPbBr${}_{3}$ perovskite, they probe the electron spin and reduce the upper limit for a Rashba effect by two orders of magnitude.