Revealing Energy Loss and Nonradiative Recombination Pathway in Mixed-Ion Perovskite Solar Cells.

Multiple-cation lead mixed-halide perovskites (MLMPs) with tunable band gaps have been demonstrated as ideal candidates to achieve perovskite solar cells with high efficiencies. It is well-known that a large open-circuit voltage (VOC) loss caused by nonradiative recombination still limits the approach to the Shockley-Queisser limit. However, there are few comprehensive contributions regarding the origin and pathway of nonradiative recombination in n-i-p structured MLMPs. Here, we compare the performance of MLMPs containing different halides and analyze the energy loss and interface trap-assisted nonradiative recombination characterizations. It is found that Br-containing devices with a lower interface trap density of 3.2 × 1013 cm-2 obtain a high VOC of 1.12 V, a small energy loss of 0.02 eV, radiative recombination current density of 8.05 × 10-21 A m-2, and total recombination current density of 22.16 mA cm-2. This work provides an opportunity to understand the device physics and reveals the nature of nonradiative recombination based on experiment and simulation.