Abstract：
Solid-state anion exchange method is easy to handle and beneficial to improve stability of CsPbX3 (X = Cl, Br, I) perovskites nanocrystals (NCs) with respect to anion exchange in liquid phase. However, the corresponding exchange rate is rather slow due to the limited diffusion rate of anions from solid phases, resulting in mixed-halide perovskite NCs. Herein, a fast and reversible post-synthetic quasi-solid-state anion exchange method in CsPbX3 NCs with inorganic potassium halide KX salts/polyvinylpyrrolidone (PVP) thin film is firstly reported. Original morphology of the exchanged NCs is well-preserved for all samples. Complete anion exchange from Br- to Cl- or I- is successfully achieved in CsPbX3 NCs within ≈20 min through possible vacancies-assisted ion exchange mechanism, under ambient conditions and vice versa. Particularly, Br- -exchanged CsPbCl3 and CsPbI3 NCs exhibit improved optical properties. Encouraged by the attractive fluorescence and persistent luminescence as well as good stability of the resulted CsPbX3 NCs, an effective dual-mode information storage-reading application is demonstrated. It is believed that this method can open a new avenue for the synthesis of other direct-synthesis challenging quantum-confined perovskite NCs/nanoplates/nanodisks or CsSnX3 NCs/thin film and provide an opportunity for advanced information storage compatible for practical applications.
摘要：
固态阴离子交换法易于操作，有利于提高CsPbX3(X=Cl,Br,I)关于液相中的阴离子交换的钙钛矿纳米晶体(NC)。然而,由于阴离子从固相的扩散速率有限，相应的交换速率相当慢，导致混合卤化物钙钛矿NC。在这里，首次报道了一种在CsPbX3NCs中与无机卤化钾KX盐/聚乙烯吡咯烷酮（PVP）薄膜进行快速可逆的后合成准固态阴离子交换方法。对于所有样品,交换的NC的原始形态被良好地保存。通过可能的空位辅助离子交换机制，CsPbX3NC在约20分钟内成功实现了从Br-到Cl-或I-的完全阴离子交换，在环境条件下，反之亦然。特别是,Br-交换的CsPbCl3和CsPbI3NC表现出改善的光学性质。受到吸引的荧光和持续发光以及所得CsPbX3NC的良好稳定性的鼓舞，演示了一种有效的双模式信息存储读取应用程序。据信，这种方法可以为合成其他直接合成具有挑战性的量子约束钙钛矿NC/纳米板/纳米盘或CsSnX3NC/薄膜开辟一条新途径，并为与实际应用兼容的高级信息存储提供机会。
