6-Trifluoromethylnicotinamide Bilaterally Anchored All Cations Implementing Efficient and Humidity-Stable Perovskite Solar Cells

For organic-inorganic hybrid perovskite solar cells (PSCs), the volatilization of organic components and the presence of undercoordinated Pb²⁺ ions are the primary causes of device stability imbalance. These factors also serve as significant determinants that restrict the commercialization scale of PSCs. Here, 6-trifluoromethylnicotinamide (TNA) molecules, featuring amide and trifluoromethyl groups at both ends, were introduced as Lewis additives into the precursor solution of perovskite to anchor all cation defect sites and optimize the crystallization process of perovskite. Theoretical calculations confirmed that the -NH₂ and C═O groups within the amide group on one side of the TNA molecule synergistically passivated the undercoordinated Pb²⁺ ions, whereas the trifluoromethyl group on the other side formed hydrogen bonds with the organic components of perovskite. The scorpion-like bilateral all-cation anchoring ability of TNA molecules was further substantiated through experimental characterization. Upon optimization of the TNA treatment concentration, a perovskite film characterized by large grains and a reduced defect density of states was achieved. The photovoltaic performance of PSCs incorporating TNA exhibited significant enhancement with an increase in efficiency from 22.42% (Control) to 24.15%. Under a harsh high-humidity environment, the comprehensive cation passivation effect of TNA significantly hindered the decomposition and phase transition of perovskite films, thereby ensuring excellent humidity stability for the PSCs.