Preparation and performance of CsPbBr3 nanocrystals in a fluorophosphate glass matrix

The encapsulation of CsPbBr₃ nanocrystals (NCs) in oxide glass can effectively avoid contact of the external environment with the halide perovskite. However, the effects of hydroxyl and oxygen on NCs cannot be completely excluded because of the nature of oxide glass itself. Here, we proposed a new solution to solve these problems by using fluorophosphate (FP) glass as the embedding matrix. The composition (Br concentration) and heat treatment conditions (temperature and time) of the glass matrix were designed and optimized to improve the optical properties of CsPbBr₃ NCs. The results showed that highly pure green light with an emission peak of 534 nm and a full-width at half-maximum (FWHM) of approximately 19 nm was achieved using CsPbBr₃ NCs@glass and a light-emitting diode (LED)/laser diode (LD). The Commission Internationale de l'Eclairage (CIE) coordinates of the two devices were (0.243, 0.723) and (0.239, 0.739), with very high color purities of 96.6% and 97.3%, respectively. The photoluminescence quantum yields (PLQYs) of the samples excited at 365 nm and 450 nm wavelengths were 34.54% and 38.85%, respectively. Additionally, the chemical stability of CsPbBr₃ NCs was significantly improved by the encapsulation in FP glass, retaining 88% of the original PL intensity after 30 days of storage in deionized water. This work provides a new choice to improve the stability of a halide perovskite in a matrix.