Efficient and Stable Perovskite/Silicon Tandem Solar Cells Modulated with Triple‐Functional Passivator

Abstract Perovskite/silicon tandem solar cells (TSCs) have aroused much attentions in recent years. One of keys for achieving highly efficient and stable TSCs is to guarantee effective charge transfer, especially on the rough textured silicon substrate due to the poor adhesion between interlayers. Here, a 2‐fluoroisonicotinic acid (2‐FNA) additive that possesses fluorine (‐F), carboxylic acid (‐COOH), and pyridine nitrogen as functional groups in the perovskite precursor to assist the crystallization process is utilized. It shows that 2‐FNA can efficiently reduce the defects and suppress non‐radiative recombination of perovskite layers by bonding with the uncoordinated Pb 2+ ions, formamidinium (FA + ), and halide vacancies, leading to notably prolonged carrier lifetime. Most importantly, this found that 2‐FNA aids in the formation of better interfacial contact between the perovskite and C 60 layer on top, thus enhancing the interfacial electron extraction therein, eventually leading to an increased power conversion efficiency (PCE) of 28.61% on champion perovskite/silicon TSCs from 27.08% on control counterparts. This work provides a practical route to further advance the PV performance and applicability of perovskite/silicon TSCs.