  Solar cells based on metal-halide perovskite absorber layers have resulted in
outstanding photovoltaic devices with long non-radiative lifetimes as a crucial
feature enabling high efficiencies. Long non-radiative lifetimes occur if the
transfer of the energy of the electron-hole pair into vibrational energy is
slow, due to, e.g., a low density of defects, weak electron phonon coupling or
the release of a large number of phonons needed for a single transition. Here,
we discuss the implications of the known material properties of metal-halide
perovskites (such as permittivities, phonon energies and effective masses) and
combine those with basic models for electron-phonon coupling and
multiphonon-transition rates in polar semiconductors. We find that the low
phonon energies of MAPbI$_3$ lead to a strong dependence of recombination rates
on trap position, which can be readily deduced from the underlying physical
effects determining non-radiative transitions. Here, we show that this is
important for the non-radiative recombination dynamics of metal-halide
perovskites, as it implies that these systems are rather insensitive to defects
that are not at midgap energy. This can lead to long lifetimes, which indicates
that the low phonon energies are likely an important factor for the high
performance of optoelectronic devices with metal halide perovskites.
