Solution-Processable Cathode Buffer Layer for High-Performance ITO/CuSCN-based Planar Heterojunction Perovskite Solar Cell

Organic-inorganic hybrid perovskite solar cells (pero-SCs) have attracted tremendous attention recently because of their excellent photovoltaic performance. Simultaneously achieving high performance and long-term stability mainly relies on improving the quality of the perovskite film and overcoming the interface losses through interface engineering. Here, we demonstrate a high performance ITO/CuSCN-based planar heterojunction pero-SCs using solution-processable perylene−diimide derivative PDINO as cathode buffer layer. The device showed a high open-circuit voltage (Voc) of 1.05 V, a hysteresis-free photovoltaic response and a maximum power conversion efficiency (PCE) of 16.4%. The high performance can be ascribed to the proper choice of the anode and cathode interface materials. In comparison with the commonly used PEDOT:PSS anode buffer layer, the CuSCN anode buffer layer can increase the built-in potential and decrease the interfacial energy barrier with CH3NH3PbI3, which results in higher Voc. The thickness-insensitive PDINO cathode buffer layer is beneficial to higher short circuit current density. The results indicate that the combination of the CuSCN anode buffer layer and PDINO cathode buffer layer is an effective way to get high photovoltaic performance of the p-i-n planar pero-SCs.