Unexpectedly strong Auger recombination in halide perovskites

The emergence of halide perovskites in solar cell applications has triggered the exploration of electron-hole recombination processes. Some experimental measurements have shown unexpectedly high Auger recombination coefficients in halide perovskites as compared to III-V semiconductors with similar band gaps, but the underlying microscopic mechanism remains unclear. In the present work, we compute the Auger recombination coefficients in the prototype halide perovskite, CH₃NH₃PbI₃ (MAPbI₃), using first-principles calculations. We demonstrate that the unexpectedly high Auger coefficient observed in MAPbI₃ is due to an accidental resonance between the band gap and a complex of bands at energies approximately equal to the gap above the conduction-band edge. Furthermore, we show that the high Auger coefficient can be suppressed by eliminating the octahedral distortions of the halide lattice.