Small Molecule Regulatory Strategy for Inorganic Perovskite Solar Cells with 368 mV of VOC Deficit and its Application in Tandem Devices

Abstract Tandem solar cells combining perovskite and silicon have witnessed rapid development in recent years. However, the top cell, utilizing wide‐bandgap perovskite as absorbers generally suffer significant open‐circuit voltage (VOC) deficit, particularly for inorganic perovskite, which poses a considerable obstacle to enhancing the power conversion efficiency (PCE). Here, a modulation strategy by using 2,6‐pyridinedicarboxamide (PC), the crystallization kinetics of inorganic perovskite film can be effectively regulated, specifically manifested as a relatively longer annealing time in the air, resulting in sufficient growth for the inorganic perovskite grains. Additionally, PC can effectively in situ passivate uncoordinated Pb2+, suppressing the non‐radiative recombination of charge carriers. Eventually, a record PCE of 22.07% is achieved based on n–i–p inorganic perovskite solar cells (IPSCs), which also demonstrate the highest VOC above 1.34 V (1.71 eV of bandgap). More importantly, the unencapsulated IPSCs show enhanced thermal stability and photostability. Furthermore, the n–i–p IPSCs are also applied to inorganic perovskite/silicon tandem solar cells (IPTSCs), a PCE of 27.27% and an impressive VOC of 2.024 V are obtained.