A novel inorganic hole-transporting material of CuInS2 for perovskite solar cells with high efficiency and improved stability

Perovskite solar cells (PSCs) have attracted more attentions in recent decade, and the power conversion efficiency (PCE) has reached 24.2%. While some issues such as cost and stability must be solved for commercialization. One of the most effective ways is to develop inorganic hole-transporting materials (HTMs) for PSCs. In the present work, CuInS 2 quantum dots (CIS QDs) were synthesized using a modified hot-injection method and applied to PSCs as an HTM. A high value of PCE (18.8%) for the optimized solar cells with CuInS 2 as an HTM was achieved, which was very close to the PCE of a device with Spiro-OMeTAD as an HTM (19.2%). Moreover, the stability of CuInS 2 -based solar cells was greatly improved compared to those made with Spiro-OMeTAD. The PCE of CuInS 2 -based solar cells only decayed by 9% of the original value after 30 days, while that of the solar cells based on Spiro-OMeTAD decayed dramatically by 33% of the original value within 15 days. These results in this study demonstrate that CuInS 2 is a promising inorganic hole-transporting material for the fabrication of PSCs with high PCE and improved stability.