Efficiency Limit of Lead Halide Perovskite Photovoltaics

Lead halide materials have seen a recent surge of interest from the photovoltaics community following the observation of surprisingly high photovoltaic performance, with opto-electronic properties similar to GaAs. This begs the question; what is the limit for the efficiency of these materials? In this article, we show that Methyl Ammonium Lead Iodide (MAPbI3), like silicon, has a larger than expected Auger coefficient, decreasing the theoretical external luminescence efficiency to $\sim$ 95% at open-circuit. The Auger penalty is much reduced at the operating point where the carrier density is less, producing an oddly high fill factor of $\sim$ 90.4%. This compensates the Auger penalty and leads to an operating point voltage and power conversion efficiency close to ideal for the MAPbI3 bandgap.