ABSTRACT The commercialization of n‐i‐p perovskite solar cells (PSCs) is hindered by the inherent instability of the spiro‐OMeTAD hole transport layer (HTL), where volatile additives and mobile lithium ions (Li + ) trigger film degradation. Herein, we introduce a multifunctional additive, 2‐Trifluoromethylphenothiazine (TFPT), to strengthen the spiro‐OMeTAD doped systems. Theoretical simulations and experimental characterizations reveal that the electron‐rich sulfur center in TFPT functions as a potent ionic anchor, exhibiting a strong binding affinity for Li + . This specific coordination effectively immobilizes the mobile dopants and suppresses the formation of detrimental clusters, while the trifluoromethyl moieties construct a robust hydrophobic barrier against moisture ingress. Consequently, this synergistic regulation induces a dense, pinhole‐free HTL morphology with optimized energy level alignment and hole mobility enhanced by nearly an order of magnitude. The resulting PSCs achieve a champion power conversion efficiency (PCE) of 26.09% (0.04 cm 2 ). Furthermore, the strategy demonstrates excellent scalability, yielding a PCE of 24.24% for 1.008 cm 2 devices. Most notably, unencapsulated devices retain approximately 90% of their initial efficiency after 800 h of continuous maximum power point tracking (MPPT) under thermal and light stress. This work establishes a promising paradigm for molecular‐level ion management to realize scalable and durable perovskite photovoltaics.
Liu et al. (Mon,) studied this question.