Two Birds with One Stone: Dual‐Functional Difluorinated Modifier Enabling Efficient and Stable Perovskite Solar Cells

Abstract

The interface between the perovskite layer and charge transport layer (CTL) plays an important role in the photoelectric conversion of perovskite solar cells (PSCs). In essence, the presence of defects and unideal contact at the perovskite/CTL interface induces severe nonradiative charge recombination, thus limiting the open‐circuit voltage and fill factor of PSCs. Herein, a two‐birds‐with‐one‐stone strategy to overcome the earlier challenges is reported, in which a single reagent 3,5‐difluorobenzenesulfonamide (3,5‐DFBS) is applied as an interface modifier between perovskite layer and spiro‐OMeTAD hole transport layer (HTL) in conventional PSCs. The 3,5‐DFBS molecules can passivate the undercoordinated Pb2+‐related surface defects by forming coordination through SO group and simultaneously strengthen the perovskite/HTL interface contact via F–π interactions, thus promoting hole extraction greatly. As a result, a champion efficiency of 23.69% with substantially improved stability is accomplished for 3,5‐DFBS PSCs. This work demonstrates that the two‐birds‐with‐one‐stone strategy is promising for achieving highly efficient and stable PSCs.