Preparation and properties of highly stabilized CsPbX3 (X = Cl, Br, I) by liquid phase molten salt method

Abstract

Coating perovskite quantum dots (PQDs) with silicon dioxide has become one of the important ways to improve the stability of CsPbX₃ (X = Cl, Br, I) PQDs. However, the problem of poor stability still exists, especially the method of preparing the above three kinds of PQDs that can achieve stability at the same time is very scarce. Here, we developed a liquid phase molten salt method to obtain triple-colour CsPbX₃ PQDs inside mesoporous SiO₂ at a low temperature (350 °C). This method enables CsPbX₃ PQDs with narrower half-peak width (23 nm, 21 nm, and 42 nm), good stability (from 20 °C to 160 °C, the luminous intensity can retain over 85.6 %), and high photoluminescent quantum yield (PLQY) (up to more than 90.2 %). The particle size of the powder obtained by this method is just several hundred nanometers. By combining CsPbBr₃, CsPbI₃ and 470 nm blue chips, white light emitting diode (WLED) with colour coordinates of (0.3101, 0.3299) were further fabricated, with a colour rendering index of 75.4, the improved stability of the CsPbX₃ PQDs also enables the prepared WLED to work more continuously for a long time. The samples can also be made into ink with different luminscence colors for screen printing, they also can be prepared into thin films with good tensile properties. Our study provides a method for preparing stable CsPbX₃ PQDs which have great application potential in the fields of WLED and screen displays.