Solvent-Free in Situ Synthesis of a CsPbBr3 Nanocrystal/ZrO2 Hybrid Phosphor with Excellent Thermal Stability for White Light-Emitting Diodes

All-inorganic cesium lead halide perovskite CsPbX₃ (X = Cl, Br, I, or mixed) nanocrystals (NCs) are emerging as promising candidates in light-emitting diodes (LEDs) owing to their excellent luminescent properties. However, CsPbX₃ NCs are extremely susceptible to the elevated temperature associated with prolonged LED operation due to their low formation energy and soft ionic crystal structure. Here, CsPbBr₃ NCs hybridized with ZrO₂ were in situ synthesized by a rapid solvent-free method under an ambient environment for the first time, which was also suitable for large-scale production. The as-prepared CsPbBr₃/ZrO₂ hybrid phosphor not only presented enhanced photoluminescence (PL) properties but also exhibited improved thermal stability. For example, the PL intensity of the CsPbBr₃/ZrO₂ hybrid phosphor could retain 70% of the initial value at 130 °C, obviously higher than that of 34% for pure CsPbBr₃. The exceptional thermal stability of the CsPbBr₃/ZrO₂ hybrid phosphor could be attributed to the introduction of ZrO₂, which effectively preserved the initial perovskite structure of CsPbBr₃ during heat treatment, as confirmed by XRD results. The as-prepared CsPbBr₃/ZrO₂ hybrid phosphor had great practical applications verified by the construction of white LEDs (WLEDs) with a luminance degradation of only 9% after continuous operation for 24 h at the initial luminance of 2000 cd m^-2, which was significantly better than that of 63% for control WLEDs. The proposed thermally stable hybrid phosphor is expected to greatly contribute to the industrialization process of perovskites.