Enhanced photovoltaic performance and stability in mixed-cation perovskite solar cells via compositional modulation

•A pure phase of FA1-xMAxPbI3 perovskite FA1-xMAxPbI3 was prepared.•Discussing effect of chemical composition and morphology on the photovoltaic performance in detail.•The PCE of PKSC based on FA0.7MA0.3PbI3 reaches up to 16.0%.•The long term stability and reproducibility is obtained.

Preparation of high-quality and pure phase mixed-organic-cation FA1-xMAxPbI3 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 FA1-xMAxPbI3 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 FA1-xMAxPbI3 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 FA0.7MA0.3PbI3 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.

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