All-inorganic halide perovskites as candidates for efficient solar cells

Hybrid perovskites currently exhibit higher efficiencies than their all-inorganic counterparts in photovoltaic applications, which has led to a common belief that the organic cation somehow suppresses defect-assisted nonradiative recombination. Using first-principles calculations, here we show that the dominant nonradiative recombination center in CsPbI3 is the iodine interstitial, which causes similar nonradiative capture rates as in MAPbI3 (MA = CH3NH3). However, the MA cation can give rise to additional strong nonradiative recombination centers such as hydrogen vacancies, which are absent from CsPbI3. One major advantage of MA+ over Cs+ is a better stability of the perovskite phase. Our study suggests that all-inorganic halide perovskites, if they can be stabilized, hold great promise for high-efficiency optoelectronic applications. These critical insights may prevent all-inorganic halide perovskites from being disregarded as potentially strong candidates for solar cell materials.