An HBr‐assisted slow cooling method is developed for the growth of centimeter‐sized Cs₄PbBr₆ crystals. The obtained crystals show strong green photoluminescence with absolute photoluminescence quantum yields up to 97%. More importantly, the evolution process and structural characterizations support that the nonstoichiometry of initial Cs₄PbBr₆ crystals induce the formation of nanosized CsPbBr₃ nanocrystals in crystalline Cs₄PbBr₆ matrices. Furthermore, high efficiency and wide color gamut prototype white light‐emitting diode devices are also demonstrated by combining the highly luminescent Cs₄PbBr₆ crystals as green emitters and commercial K₂SiF₆:Mn⁴⁺ phosphor as red emitters with blue emitting GaN chips. The optimized devices generate high‐quality white light with luminous efficiency of ≈151 lm W⁻¹ and color gamut of 90.6% Rec. 2020 at 20 mA, which is much better than that based on conventional perovskite nanocrystals. The combination of improved efficiency and better stability with comparable color quality provides an alternative choice for liquid crystal display backlights.

中文翻译：

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厘米级的Cs4PbBr6晶体与嵌入的CsPbBr3纳米晶体表现出优异的光致发光性能：非化学计量诱导的转变和发光应用

开发了一种HBr辅助的缓慢冷却方法，用于生长厘米级的Cs ₄ PbBr ₆晶体。所获得的晶体显示出强绿色光致发光，绝对光致发光量子产率高达97％。更重要的是，演化过程和结构表征支持初始Cs ₄ PbBr ₆晶体的非化学计量诱导了晶体Cs ₄ PbBr ₆基质中纳米级CsPbBr ₃纳米晶体的形成。此外，还通过结合高发光Cs ₄ PbBr ₆展示了高效率和宽色域原型白色发光二极管器件。晶体作为绿色发射器，商用K ₂ SiF ₆：Mn ⁴⁺磷光体作为红色发射器，具有发射蓝色的GaN芯片。经过优化的器件可产生高质量的白光，发光效率约为151 lm W ^-1，色域为90.6％Rec。2020年时为20 mA，这比传统的钙钛矿纳米晶体要好得多。效率提高，稳定性更好以及可比的色彩质量相结合，为液晶显示器背光源提供了另一种选择。