Buried interface defects passivation of perovskite film by choline halide for high performance inverted perovskite solar cells with efficiency exceeding 22%

Defect-induced charge carrier recombination between charge transport layers and perovskite layer limits the further improvement of the performance of perovskite solar cells (PSCs). Defect passivation is a promising path for further development improves in the open-circuit voltage (VOC) and the short-circuit current density (JSC) of PSCs. Here, we report a simple method via spin-coating choline halide to passivate buried interface defects of perovskite applied to inverted PSCs. The introduction of choline chloride (CHCl) can remarkably improve the crystalline quality of perovskite films, speed up the transport of carriers and reduce the trap density in perovskite, which universally enhance the performance of PSCs. Finally, the champion CHCl modified device got a high PCE of 22.61% with negligible hysteresis, which is one of the highest efficiencies of inverted PSCs fabricated with a two-step method. This optimization can also improve the stability of PSCs, the CHCl modified device without encapsulation maintained 89% of its initial PCE in air with a relative humidity of 40 ± 5% after near 800 h ageing. This work reveals an effective way of using choline halide for buried interface defects passivation of perovskite film to further improve both the stability and efficiency of solar cells.