Dual Interfacial Modifications Enable High Performance Semitransparent Perovskite Solar Cells with Large Open Circuit Voltage and Fill Factor

In this work, both anode and cathode interfaces of p-i-n CH₃NH₃PbI₃ perovskite solar cells (PVSCs) are simultaneously modified to achieve large open-circuit voltage (V_oc) and fill factor (FF) for high performance semitransparent PVSCs (ST-PVSCs). At the anode, modified NiO serves as an efficient hole transport layer with appropriate surface property to promote the formation of smooth perovskite film with high coverage. At the cathode, a fullerene bisadduct, C₆₀(CH₂)(Ind), with a shallow lowest unoccupied molecular orbital level, is introduced to replace the commonly used phenyl-C₆₁-butyric acid methyl ester (PCBM) as an alternative electron transport layer in PVSCs for better energy level matching with the conduction band of the perovskite layer. Therefore, the V_oc, FF and power conversion efficiency (PCE) of the PVSCs increase from 1.05 V, 0.74 and 16.2% to 1.13 V, 0.80 and 18.1% when the PCBM is replaced by C₆₀(CH₂)(Ind). With the advantages of high V_oc and FF, ST-PVSCs are also fabricated using an ultrathin transparent Ag as cathode, showing an encouraging PCEs of 12.6% with corresponding average visible transmittance (AVT) over 20%. These are the highest PCEs reported for ST-PVSCs with similar AVTs paving the way for using ST-PVSCs as power generating windows.