Quasiparticle Self-Consistent GW

Metal-organic perovskite solar cells, CH3NH3PbI3 (MAPI) in particular, have attracted much attention recently because of their high power conversion efficiency and potential low cost.

The material exhibits strong absorptivity characteristic of a direct-gap semiconductor, while showing extraordinarily slow radiative recombination times, reminiscent of an indirect-gap semiconductor. This is widely thought to be the key to the very high efficiencies in the device.

In APL Materials 4, 091501 (2016), we provide a simple explanation for the origin of this effect, as a consequence of large spin-orbit coupling combined with large internal electric fields. Together, they create a Rashba effect which slightly spin-splits the bands at the direct-gap point. We develop a theory of photoluminescence based on the Quasiparticle Self-Consistent GW approximation, and obtain good agreement for the recombination rate with experiment.