Compared to red and green organic light-emitting diodes (OLEDs), blue OLEDs are still the bottleneck due to the lack of efficient emitters with simultaneous high exciton utilization efficiency (EUE) and short excited-state lifetime. Different from the fluorescence, phosphorescence, thermally activated delayed fluorescence (TADF), and organic radical materials traditionally used in OLEDs, we demonstrate herein a new type of emitter, cerium(III) complex Ce-1 with spin-allowed and parity-allowed d–f transition of the centre Ce³⁺ ion. The compound exhibits a high EUE up to 100% in OLEDs and a short excited-state lifetime of 42 ns, which is considerably faster than that achieved in efficient phosphorescence and TADF emitters. The optimized OLEDs show an average maximum external quantum efficiency (EQE) of 12.4% and Commission Internationale de L’Eclairage (CIE) coordinates of (0.146, 0.078).

与红色和绿色有机发光二极管（OLED）相比，蓝色OLED仍然是瓶颈，因为缺乏同时具有高激子利用效率（EUE）和短激发态寿命的高效发射器。与OLED中传统使用的荧光、磷光、热激活延迟荧光（TADF）和有机自由基材料不同，我们在此展示了一种新型发射体，具有自旋允许和宇称允许d的铈（III）配合物Ce-1 。 –中心 Ce ^3+离子的f跃迁。该化合物在 OLED 中表现出高达 100% 的高 EUE 和 42 ns 的短激发态寿命，这比高效磷光和 TADF 发射器中实现的寿命要快得多。优化后的 OLED 的平均最大外量子效率 (EQE) 为 12.4%，国际照明委员会 (CIE) 坐标为 (0.146, 0.078)。