Blue organic light-emitting diode (OLED) is still a challenge among the RGB ones due to the lack of emitter simultaneously has short excited state lifetime and high theoretical external quantum efficiency (EQE). We demonstrate herein a blue emissive rare earth cerium(III) complex Ce-2 showing a high photoluminescence quantum yield of 95% and a short excited state lifetime of 52.0 ns in doped film, which is considerably faster than that achieved in typical efficient phosphorescence or thermally activated delayed fluorescence emitters (typical lifetimes > 1 μs). The corresponding OLED shows a maximum EQE up to 20.8% and a still high EQE of 18.2% at 1000 cd m⁻², as well as a 70 times longer operation lifetime than a classic phosphorescence OLED. The excellent performance indicates that cerium(III) complex could be a candidate for efficient and stable blue OLEDs because of its spin- and parity-allowed d-f transition from Ce³⁺ ion.

中文翻译：

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用于蓝色有机发光二极管的具有纳秒 df 发射的高效稀土铈 (III) 配合物

蓝色有机发光二极管（OLED）由于缺乏发射体，同时激发态寿命短，理论外量子效率（EQE）高，仍然是RGB发光二极管中的一个挑战。我们在此展示了一种蓝色发射稀土铈 (III) 配合物Ce-2，在掺杂膜中显示出 95% 的高光致发光量子产率和 52.0 ns 的短激发态寿命，这比典型的高效磷光或热激活延迟荧光发射器（典型寿命 > 1 μs）。相应的 OLED 在 1000 cd m ^{-2 下}显示出高达 20.8% 的最大 EQE 和 18.2% 的仍然高的 EQE，以及比经典磷光 OLED 长 70 倍的使用寿命。优异的性能表明，铈 (III) 配合物可以成为高效和稳定的蓝色 OLED 的候选者，因为它允许自旋和奇偶校验从 Ce ³⁺离子的df跃迁。