Double-functional additive strategy for efficient perovskite solar cells

Perovskite solar cells (PSCs) efficiency has recently achieved significant advancements, surpassing the 26% threshold. Excessive PbI₂, often used in high-efficiency PSCs, will also cause stability or defect problems. To address these challenges, we introduce anionic and cationic bifunctional additives to passivate PSCs synergistically. Phenylethylamine trifluoroacetate (PEATFA) is utilized as an additive to passivate the perovskite film. The PEA⁺ cation facilitates the formation of two-dimensional perovskite while TFA⁻ anion passivate the uncoordinated Pb²⁺ ions and iodine vacancies, enhancing perovskite crystal quality without excess PbI₂. Furthermore, PEATFA modification optimizes the energy level matching between the perovskite and charge transfer layers, thereby enhancing charge transfer and extraction capabilities. Finally, the device achieves an impressive power conversion efficiency of 24.05% while exhibiting minimal hysteresis and good stability.