Highly Ambient Stable CsSnBr3 Perovskite via a New Facile Room-Temperature “Coprecipitation” Strategy

Tin-based perovskites are becoming promising alternatives to lead-based perovskites with eco-friendly merit and tantalizing photophysical properties. Unfortunately, the lack of facile, low-cost synthesis approaches associated with extremely poor stability greatly restrict their practical applications. Herein, a facile room-temperature "coprecipitation" method utilizing ethanol (EtOH) solvent and salicylic acid (SA) additive is proposed for synthesizing highly stable cubic phase CsSnBr3 perovskite. Experimental results show that ethanol solvent and SA additive can not only effectively prevent the oxidation of Sn2+ during the synthesis processes but also stabilize the as-synthesized CsSnBr3 perovskite. These are mainly ascribed to the protection effect of ethanol and SA, which are attached on the surface of CsSnBr3 perovskite by coordinating with Br- and Sn2+ ions, respectively. As a result, CsSnBr3 perovskite can be obtained in open air and exhibits exceptional oxygen resistibility under moist air conditions (temperature: 24.2-25.8 °C; relative humidity: 63-78%). Absorption remains unchanged and photoluminescence (PL) intensity is vastly maintained (∼69%) after storage for 10 days, better than bulk CsSnBr3 perovskite film synthesized by spin-coating method whose PL intensity is decreased to 43% after storage for 12 h. This work represents a step toward stable tin-based perovskite by a facile and low-cost strategy.