Flat panel displays enjoy 100 billion-dollar markets with significant penetration in daily life, which require efficient, color-saturated blue, green, and red light-emitting diodes (LEDs). The recently emerged halide perovskites have demonstrated low-cost and outstanding performance for potential LED applications. However, the performance of blue perovskite LEDs (PeLEDs) lags far behind red and green cousins, particularly for color coordinates approaching (0.131, 0.046) that fulfill the Rec. 2020 specification for blue emitters. Here, a high-efficiency, lead-free perovskite, CsEuBr₃, is reported that exhibits bright blue exciton emission centered at 448 nm with a color coordinates of (0.15, 0.04), contributed from Eu-5d→Eu-4f/Br-4p transition with an optical band gap of 2.85 eV. Further optical characterizations reveal its short excited-state lifetime of 151 ns, excellent exciton diffusion diffusivity of 0.0227 cm² s⁻¹, and high quantum yield of ≈69%. Inspired by these findings, deep-blue PeLEDs based on all-vacuum processing methods, which have been demonstrated as the most successful approach for the organic LED industry, are constructed. The devices show a maximum external quantum efficiency of 6.5% with an operating half-lifetime of 50 mins at an initial brightness of 15.9 cd m⁻². It is anticipated that this work will inspire further research on lanthanide-based perovskites for next-generation LED applications.

中文翻译：

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基于铕卤化物钙钛矿的高效蓝光发光二极管

平板显示器拥有 1000 亿美元的市场，在日常生活中占有重要地位，这需要高效、色彩饱和的蓝色、绿色和红色发光二极管 (LED)。最近出现的卤化物钙钛矿已在潜在的 LED 应用中展示了低成本和出色的性能。然而，蓝色钙钛矿 LED (PeLED) 的性能远远落后于红色和绿色同类产品，特别是对于接近 (0.131, 0.046) 的满足蓝色发射器规范的 Rec. 2020 的色坐标。在这里，一种高效的无铅钙钛矿 CsEuBr ₃，据报道，表现出以 448 nm 为中心的亮蓝色激子发射，颜色坐标为 (0.15, 0.04)，来自 Eu-5d → Eu-4f / Br-4p 跃迁，光学带隙为 2.85 eV。进一步的光学表征揭示了其 151 ns 的短激发态寿命、0.0227 cm ² s ^{-1 的}优异激子扩散扩散率和 ≈69% 的高量子产率。受这些发现的启发，构建了基于全真空处理方法的深蓝色 PeLED，该方法已被证明是有机 LED 行业最成功的方法。这些器件在 15.9 cd m ^-2的初始亮度下显示出 6.5% 的最大外部量子效率和 50 分钟的工作半衰期. 预计这项工作将激发对用于下一代 LED 应用的镧系元素钙钛矿的进一步研究。