Surface Modification with CuFeS 2 Nanocrystals to Improve the Efficiency and Stability of Perovskite Solar Cells.

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 CuFeS 2 nanocrystals and applied them to modify the perovskite surface. The efficiency of the PSCs with CuFeS 2 modification is improved to 20.17% from 18.64% for the control devices. Some investigations demonstrate that the CuFeS 2 modification passivates the perovskite surface defects and induces better energy band arrangement. Furthermore, the stability of the PSCs with CuFeS 2 modification is improved compared with the devices without CuFeS 2 modification. The efficiency of the PSCs with CuFeS 2 modification maintains 93% of its initial value, whereas that of the devices without CuFeS 2 modification decreases to 61% of the initial value. This work demonstrates that CuFeS 2 is a novel material used as a modification layer to enhance the efficiency and stability of the PSCs.