Multifunctional ionic liquid to extend the expiration date of precursor solution for perovskite photovoltaics

At present, the development of perovskite solar cells (PSCs) is progressing rapidly, but the issue of poor stability remains a significant challenge. Achieving a stable precursor solution is crucial for the large-scale production of high-quality PSC films. In this study, we successfully developed a strategy to improve the long-term stability of the precursor solution and improve device performance by employing 1-n-butyl-3-methylimidazolium di-n-butyl phosphate (BMIMBP) as an anti-aging additive. The BP⁻ component inhibits the reactivity of I⁻ and formamidinium ion through multiple chemical bonds, thereby stabilizing the precursor solution. In addition, the BMIM⁺ component, which contains an amino group, can form two-dimensional perovskite internally, further enhancing the device stability. This strategy provides valuable guidance for achieving long-term stability in solar cells.