Metal-halide perovskite (MHP) solar cells exhibit long nonradiative lifetimes as a crucial feature enabling high efficiencies. Long nonradiative lifetimes occur if the transfer of electronic into vibrational energy is slow due to, e.g., a low trap density, weak electron-phonon coupling, or the requirement to release many phonons in the electronic transition. Here, we combine known material properties of MHPs with basic models for electron-phonon coupling and multiphonon-transition rates in polar semiconductors. We find that the low phonon energies of MAPbI3 lead to a strong dependence of recombination rates on trap position, which we deduce from the underlying physical effects determining nonradiative transitions. This is important for nonradiative recombination in MHPs, as it implies that they are rather insensitive to defects that are not at midgap energy, which can lead to long lifetimes. Therefore, the low phonon energies of MHPs are likely an important factor for their optoelectronic performance.

Centre for Advanced Photovoltaics Czech Technical University 166 36 Prague 6 Czech Republic

Engineering Sciences University of Southampton Southampton SO17 1BJ United Kingdom

Faculty of Engineering and CENIDE University of Duisburg Essen Carl Benz Straße 199 47057 Duisburg Germany

IEK5 Photovoltaics Forschungszentrum Jülich 52425 Jülich Germany

Institute of Theoretical Physics University of Regensburg 93040 Regensburg Germany

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