Effect of Bathocuproine Concentration on the Photovoltaic Performance of NiOx-Based Perovskite Solar Cells

Bathocuproine (BCP) (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline) is a well-known material that is employed as a hole-blocking layer between electron transport layer (ETL) and metal electrode in perovskite solar cells. It has been demonstrated that the use of BCP as a buffer layer between the ETL and the metal electrode in perovskite solar cells is highly beneficial. In literature, BCP is coated using vacuum processing techniques. Vacuum processing techniques require more energy and cost-effective processing conditions. In this work, we used BCP layers processed through wet processing techniques using sol-gel method with different concentrations. We achieved a short circuit current density (Jsc) of 16.1 mA/cm² and an open circuit voltage (Voc) of 875 mV were acquired and a fill factor (FF) of 0.37 was calculated for perovskite solar cells without a BCP layer leading to a power conversion efficiency (PCE) of 5.32 % whereas Jsc of 19 mA/cm2, Voc of 990 mV were achieved and a FF of 0.5 was calculated for perovskite solar cells employing BCP layers with concentration of 0.5 mg/ml and spin cast at 4000 rpm, leading to a PCE of 9.4 %. It has been observed that the use of a BCP layer with an optimized concentration led to an improved device performance with an increase of 77 % in PCE in ambient air under high humidity conditions for planar structure perovskite solar cells in the configuration of ITO/NiOx/MAPbI3/PCBM/BCP/Ag.