Solvent-Free\nin Situ Synthesis of a CsPbBr<sub>3</sub> Nanocrystal/ZrO<sub>2</sub> Hybrid Phosphor with Excellent Thermal\nStability for White Light-Emitting Diodes

All-inorganic\ncesium lead halide perovskite CsPbX<sub>3</sub> (X\n= Cl, Br, I, or mixed) nanocrystals (NCs) are emerging as promising\ncandidates in light-emitting diodes (LEDs) owing to their excellent\nluminescent properties. However, CsPbX<sub>3</sub> NCs are extremely\nsusceptible to the elevated temperature associated with prolonged\nLED operation due to their low formation energy and soft ionic crystal\nstructure. Here, CsPbBr<sub>3</sub> NCs hybridized with ZrO<sub>2</sub> were in situ synthesized by a rapid solvent-free method under an\nambient environment for the first time, which was also suitable for\nlarge-scale production. The as-prepared CsPbBr<sub>3</sub>/ZrO<sub>2</sub> hybrid phosphor not only presented enhanced photoluminescence\n(PL) properties but also exhibited improved thermal stability. For\nexample, the PL intensity of the CsPbBr<sub>3</sub>/ZrO<sub>2</sub> hybrid phosphor could retain 70% of the initial value at 130 °C,\nobviously higher than that of 34% for pure CsPbBr<sub>3</sub>. The\nexceptional thermal stability of the CsPbBr<sub>3</sub>/ZrO<sub>2</sub> hybrid phosphor could be attributed to the introduction of ZrO<sub>2</sub>, which effectively preserved the initial perovskite structure\nof CsPbBr<sub>3</sub> during heat treatment, as confirmed by XRD results.\nThe as-prepared CsPbBr<sub>3</sub>/ZrO<sub>2</sub> hybrid phosphor\nhad great practical applications verified by the construction of white\nLEDs (WLEDs) with a luminance degradation of only 9% after continuous\noperation for 24 h at the initial luminance of 2000 cd m<sup>–2</sup>, which was significantly better than that of 63% for control WLEDs.\nThe proposed thermally stable hybrid phosphor is expected to greatly\ncontribute to the industrialization process of perovskites.