LAUSR

Abstract Preparation of high-quality and pure phase mixed-organic-cation FA 1-x MA x PbI 3 perovskite film is a big challenge, especially on a porous oxide scaffold for mesoscopic perovskite solar cells. In this study, we fabricated a pure phase of mixed-organic-cation perovskite FA 1-x MA x PbI 3 simply using a conventional two-step method. Effect of chemical composition and morphology on the photovoltaic performance and stability of the mixed-organic-cation perovskite has been studied in details. Results show that the FA 1-x MA x PbI 3 perovskite thin films with a FA + :MA + molar ratio of 0.7:0.3 demonstrate the best photovoltaic performance. Mesoscopic perovskite solar cells fabricated using these FA 0.7 MA 0.3 PbI 3 thin films yield a power conversion efficiency (PCE) up to 16.0%. Moreover, the devices present a superior stability and the unsealed devices exposed in ambient condition (25 °C, 50%–60% relative humidity) can maintain their photoelectric performance without apparent PCE loss for up to 20 days.