Organic Halide PEACl for Surface Passivation and Defects Suppression in Perovskite Solar Cells

In recent times, mixed cation-based perovskite has gained a lot of popularity in high-performance solar cells. However, the mixed cations based on the FAxMA1–xPbI3 absorber layer still exhibit a higher trap state density, which decreases the overall performance, especially in the open-circuit voltage (VOC) and fill factor (FF). Herein, we show that surface passivation by the organic halide PEACl is an effective way to reduce the trap state density. This efficient PEACl treatment reduces the halide deficiency present at the perovskite surface and reduces surface defects and nonradiative recombination. The resultant perovskite solar cell exhibits a higher VOC (1.15 V), 92% of the Shockley-Queisser limit (1.25 V), and a higher FF than standard perovskite.