mixture at 150 °C for 2 min and then Cs-oleate solution (0.4 mL in ODE) was quickly injected. After 5 s, the reaction mixture was cooled by the ice-water bath to room temperature.

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The photoluminescence quantum yield (PLQY) of CsPbBr3 perovskite nanocrystals (NCs) prepared by the hot‐injection method can exceed 90%, which have attracted intensive attention for white light‐emitting diodes (WLEDs). However, the whole hot‐injection experiment requires air isolation and relatively high temperature. In addition, the poor stability of CsPbBr3 NCs impedes their applications. Here, a facile method is reported to synthesize CsPbBr3@ZrO2 NCs at room temperature in air. Owing to using ZrO2 coated CsPbBr3 NCs, the prepared CsPbBr3@ZrO2 NCs not only present a PLQY of 80% but also exhibit an enhanced stability to heat and moisture. Furthermore, WLEDs are fabricated with CsPbBr3@ZrO2 NCs and commercial red phosphors (CaAlSiN3:Eu2+) on blue LEDs chips. The fabricated WLEDs exhibit a correlated color temperature (CCT) of 4743 K and luminous efficacy as high as 64.0 Lm W–1. In addition, visible light communication with a high data rate of 33.5 Mbps is achieved using the WLEDs. This work provides a room temperature strategy to coat zirconia for CsPbBr3@ZrO2 NCs, benefiting to enhance the optical performance and stability, as well as the promotion of the great potentials in solid‐state illuminating and visible light communication applications.

All-inorganic CsPbBr 3 perovskite quantum dots (QDs) have received great attention in white light emission because of their outstanding properties. However, their practical application is hindered by poor stability. Herein, we propose a simple strategy to synthesize excellent stability and efficient emission of CsPbBr 3 QDs by using 2-hexyldecanoic acid (DA) as a ligand to replace the regular oleic acid (OA) ligand. Thanks to the strong binding energy between DA ligand and QDs, the modified QDs not only show a high photoluminescence quantum yield (PLQY) of 96% but also exhibit high stability against ethanol and water. Thereby warm white light-emitting diodes (WLEDs) are constructed by combining ligand modified CsPbBr 3 QDs with red AgInZnS QDs on blue emitting InGaN chips, exhibiting a color rendering index of 93, a power efficiency of 64.8 lm/W, a CIE coordinate of (0.44, 0.42) and correlated color temperature value of 3018 K. In addition, WLEDs based on ligand modified CsPbBr 3 QDs also exhibit better thermal performance than that of WLEDs based on the regular CsPbBr 3 QDs. The combination of improved efficiency and better thermal stability with high color quality indicates that the modified CsPbBr 3 QDs are ideal for WLEDs application.

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All inorganic CsPbBr 3 perovskite quantum dots (QDs) have been recognized as promising optical materials to fabricate green light emission devices because of their excellent optical performance. However, regular CsPbBr 3 QDs with an oleic acid (OA) ligand show poor stability, which limits their practical application. We replaced the OA ligand in CsPbBr 3 QDs with a 2-hexyldecanoic acid (DA) ligand and, in the synthesis, found that the new material has better optical properties than regular CsPbBr 3 QDs ( CsPbBr 3 - OA QDs). Due to the strong binding energy between the DA ligand and QDs, the ligand-modified CsPbBr 3 QDs ( CsPbBr 3 - DA QDs) show a high photoluminescence quantum yield (PLQY) of 96%, while the PLQY of CsPbBr 3 - OA QDs is 84%. Subsequently, the CsPbBr 3 QDs coated on the blue light-emitting diode (LED) chips as green phosphors are demonstrated. The color conversion from blue to pure green is achieved by adding the CsPbBr 3 - OA QDs solution up to 60 μL, while the pure green emission devices only need 18 μL CsPbBr 3 - DA QDs solution under the same concentration. The ultrapure, highly efficient green light-emitting devices based on CsPbBr 3 - DA QDs exhibit a luminous efficiency of 43.6 lm/W with a CIE (0.2086, 0.7635) under a 15.3 mA driving current. In addition, the green emission wavelength of the devices based on CsPbBr 3 - DA QDs almost has no shift, even under a high injection current. These results highlight the promise of DA ligand-modified CsPbBr 3 QDs for light-emitting devices and enrich the application field of ligand-modified CsPbBr 3 QDs.

All-inorganic cesium lead bromide ( CsPbBr 3 ) perovskite quantum dots (QDs) with excellent optical properties have been regarded as good gain materials for amplified spontaneous emission (ASE). However, the poor stability as the results of the high sensitivity to heat and moisture limits their further applications. Here, we report a facile one-pot approach to synthesize CsPbBr 3 @ SiO 2 QDs at room temperature. Due to the effective defects passivation using SiO 2 , as-prepared CsPbBr 3 @ SiO 2 QDs present an enhanced photoluminescence quantum yield (PLQY) and chemical stability. The PLQY of CsPbBr 3 @ SiO 2 QDs reaches 71.6% which is higher than 46% in pure CsPbBr 3 QDs. The PL intensity of CsPbBr 3 @ SiO 2 QDs maintains 84% while remaining 24% in pure CsPbBr 3 after 80 min heating at 60°C. The ASE performance of the films is also studied under a two-photon-pumped laser. Compared with the films using pure CsPbBr 3 QDs, those with as-prepared CsPbBr 3 @ SiO 2 QDs exhibit a reduced threshold of ASE. The work suggests that room-temperature-synthesized SiO 2 -coated perovskites QDs are promising candidates for laser devices.

Room temperature synthesis of Sn2+ doped CsPbBr3 QDs show a high PLQY of 82.77% and their corresponding WLEDs exhibit a CRI of 89 and a CCT of 3954.