Interfacial engineering of CuSCN-based perovskite solar cells via PMMA interlayer toward enhanced efficiency and stability

CuSCN has been considered as one of the most promising inorganic hole transporting materials for perovskite solar cells (PSCs). However, damaging effects during the deposition of CuSCN and interfacial degradation are detrimental to the photovoltaic performance of CuSCN-based perovskite solar cells. In this work, we demonstrated that a new method based on interfacial engineering could overcome the issues mentioned above effectively. With the introduction of an ultrathin PMMA layer between the interface of CH3NH3PbI3 and CuSCN, the corresponding perovskite solar cells exhibited enhanced power conversion efficiency and thermal stability, which mainly benefited from the reduction of trap density of perovskite thin films by PMMA and the prevention from the degradation reaction between CH3NH3PbI3 and CuSCN. As a result, the present interfacial engineering method realized an enhanced efficiency over 19%, and superior device stability with 90% retainment of the efficiency after aging at 85 °C for 96 h.