Formation of pristine CuSCN layer by spray deposition method for efficient perovskite solar cell with extended stability

By employing CuSCN, a low-cost inorganic hole transporting material (HTM), CH3NH3PbI3 perovskite solar cell (PSC) devices with high efficiency and extended stability were successfully fabricated in this work. In particular, we developed a facile method of depositing CuSCN layer reproducibly by a simple spray deposition technique, which allows the formation of the CuSCN layer without any significant damage of the underlying CH3NH3PbI3 layer. The fabricated PSC with ~50 nm-thick pristine CuSCN layer exhibits the photovoltaic conversion efficiency (PCE) of 17.10% with JSC of 23.10 mA/cm2, VOC of 1,013 mV and FF of 0.731. Compared with conventional PSCs based on spiro-OMETAD HTM, the PSC employing CuSCN exhibits higher value of JSC, suggesting that CuSCN transports holes more efficiently than spiro-OMETAD. Furthermore, PSCs employing the pristine CuSCN demonstrate a remarkable long-term stability at ambient condition with the decrease of PCE by only 5.8% after 100 days. In addition, the PCE decrease during the encapsulation process at 120 °C was merely 13%, which is much lower value than ~70% observed for the conventional device based on spiro-OMETAD, indicating excellent thermal stability of the CuSCN-based PSCs.