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 CH 3 NH 3 PbI 3 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, C 60 (CH 2 )(Ind), with a shallow lowest unoccupied molecular orbital level, is introduced to replace the commonly used phenyl‐C 61 ‐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 C 60 (CH 2 )(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.