Low-Cost Perovskite Solar Cells Employing Carbon Black/Graphite Composite and Copper (I) Thiocyanate

In this report, a low-cost and low-temperature-processed carbon black/graphite composite counter electrode (CE) was developed for a perovskite (CH3NH3PbI3) solar cell with CuSCN as a hole-transporting material. The composite CE with optimal ratio (carbon black: graphite = 1:3) exhibited an efficiency of 6.19% in a mesoscopic perovskite solar device without HTM. The improved photovoltaic performance of the device could be attributed to the higher conductivity of the composite CE as well as to the strong interfacial connection between the CE and the perovskite layer in the device. The efficiency was increased up to 8.43% by use of CuSCN as HTM because of the improved hole-transport capacity by the CuSCN layer. Further, the optimized device based on the CuSCN HTM and composite CE showed superior stability at the ambient condition for 150 h. Therefore, this study effectively fabricated a cost-effective and stable perovskite solar cell that has practical applications and can be produced on a large scale.