Surface Modification with CuFeS

Poor stability retards the industrialization of perovskite solar cells (PSCs). One of the effective ways to solve this issue is to modify the perovskite surface to improve the efficiency and stability of the PSCs. Herein, we synthesized CuFeS2 nanocrystals and applied them to modify the perovskite surface. The efficiency of the PSCs with CuFeS2 modification is improved to 20.17% from 18.64% for the control devices. Some investigations demonstrate that the CuFeS2 modification passivates the perovskite surface defects and induces better energy band arrangement. Furthermore, the stability of the PSCs with CuFeS2 modification is improved compared with the devices without CuFeS2 modification. The efficiency of the PSCs with CuFeS2 modification maintains 93% of its initial value, whereas that of the devices without CuFeS2 modification decreases to 61% of the initial value. This work demonstrates that CuFeS2 is a novel material used as a modification layer to enhance the efficiency and stability of the PSCs.