Stability and Efficiency Enhancement of Perovskite Solar Cells Using Phenyltriethylammonium Iodide

Abstract Controlling the perovskite film surface is key to improving both the stability and photovoltaic performance of perovskite solar cells. In particular, surface defects on the perovskite films, which are fundamental issues, must be passivated. This work presents a 2D organic material phenyltriethylammonium iodide (PTEAI) to passivate a 3D (FAPbI 3 ) 1− x (MAPbBr 3 ) x perovskite film surface. PTEAI forms a well‐matched conformal layer on the perovskite film, protecting the film surface from moisture by preventing the escape of organic ions from the film. The N + cations and I − anions in PTEAI form bonds with the locally charged perovskite surface, reducing the surface defect density as well as the impeding non‐radiative recombination while enhancing carrier lifetimes. These PTEAI features facilitate significant enhancements in both the open‐circuit voltage ( V OC ) and fill factor (FF) of the perovskite solar cells. As a result, the champion PTEAI‐based perovskite solar cell exhibits the highest power conversion efficiency of 20.2% compared with 18.8% by the pristine device. Additionally, the PTEAI‐treated device retains 92% of its initial efficiency after being stored in ambient air at room temperature and a relative humidity of 40–60% for 500 h without encapsulation.