First-principles evidence of strong radiative recombination in hybrid perovskites

Understanding the origin of the high solar conversion efficiency of hybrid perovskites is one key research focus in the field. A number of research groups attributed the high efficiency to low radiative recombination due to strong Rashba spin-orbit coupling. In this work, we perform first-principles calculations to explicitly compute the radiative recombination coefficient in the prototypical hybrid perovskite, CH₃NH₃PbI₃. We demonstrate that the radiative recombination in hybrid perovskites is actually strong, and that spin-orbit coupling has only a minor impact on radiative recombination. The computed radiative recombination coefficient is around 10^-10 cm³s^-1, which is as high as in typical direct-gap semiconductors. The demonstrated high radiative recombination coefficient thus enables promising applications in light-emitting diodes. However, our first-principles calculations of nonradiative rates show that strong Auger recombination may suppress efficiency. Fortunately, our insights into the origins of the strong Auger recombination indicates potential avenues for engineering the Auger coefficient.