Buried Interface Reconstruction Strategy Realizes Efficient and Stable Perovskite Solar Cells
Xiangning Xu, Jiande Lin, Qili Song, Xinli Wang, Cheng Mu, Zhichao Lin
Abstract
Abstract The buried interface in n‐i‐p structured perovskite solar cells (PSCs), typically rich in defects, is a critical target for functional molecule passivation strategies to enhance device performance. In this study, three functional molecules bearing different electron‐withdrawing groups are investigated to modify the perovskite/electron transport layer (ETL) interface. Remarkably, all three molecules exhibit a dual‐anchoring behavior: simultaneously binding to the SnO 2 ETL surface using both head and tail functional groups, a binding mode not previously reported. Three passivation molecules bearing distinct electron‐withdrawing groups are designed and evaluated: sodium trifluoroacetate (NaTFA), sodium trifluoromethanesulfinate (NaTTSA), and sodium trifluoromethanesulfonate (NaTSA), collectively referred to as NaTXA. Among them, NaTSA containing a sulfonic acid (─SO 3 ) group, exhibits strongest interfacial binding and most effective passivation, outperforming NaTTSA (─SO 2 ) and NaTFA (─COOH). This enhancement is attributed to the stronger electron‐withdrawing nature of the ─SO 3 group and its favorable energy‐level alignment at the buried interface, which minimizes defects at the interface and ensures high‐speed carrier transport. As a result, the optimized device achieves a power conversion efficiency (PCE) of 25.60% with substantially improved operational stability. This work provides critical insights into functional group selection for interface engineering and deepens the mechanistic understanding of molecule‐mediated passivation strategies in PSCs.