Organic light-emitting diodes (OLEDs) are a promising light-source technology for future generations of display^1,2. Despite great progress^{3,4,5,6,7,8,9,10,11,12}, it is still challenging to produce blue OLEDs with sufficient colour purity, lifetime and efficiency for applications. Here, we report pure-blue (Commission Internationale de l’ Eclairage (CIE) coordinates of 0.13, 0.16) OLEDs with high efficiency (external quantum efficiency of 32 per cent at 1,000 cd m⁻²), narrow emission (full-width at half-maximum of 19 nm) and good stability (95% of the initial luminacnce (LT₉₅) of 18 hours at an initial luminance of 1,000 cd m⁻²). The design is based on a two-unit stacked tandem hyperfluorescence OLED with improved singlet-excited-state energy transfer from a sky-blue assistant dopant exhibiting thermally activated delayed fluorescence (TADF) called hetero-donor-type TADF(HDT-1) to a pure-blue emitter. With stricter control of device fabrication and procedures it is expected that device lifetimes will further improve to rival commercial fluorescent blue OLEDs.

有机发光二极管 (OLED) 是一种很有前途的光源技术，可用于下一代显示器^1,2。尽管取得了巨大的进步^{3,4,5,6,7,8,9,10,11,12}，但生产具有足够色纯度、寿命和应用效率的蓝色 OLED 仍然具有挑战性。在这里，我们报告了纯蓝色（国际照明委员会 (CIE) 坐标为 0.13、0.16）OLED，具有高效率（在 1,000 cd m ^-2时外量子效率为 32% ）、窄发射（全宽19 nm 的半最大值）和良好的稳定性（在 1,000 cd m ^-2的初始亮度下 18 小时的初始亮度(LT _{95 ) 的 95%）}）。该设计基于两单元堆叠串联超荧光 OLED，具有改进的单重激发态能量转移，从天蓝色辅助掺杂剂表现出称为异质供体型 TADF (HDT-1) 的热激活延迟荧光 (TADF) 到纯蓝色发射器。随着对器件制造和程序的更严格控制，预计器件寿命将进一步提高，以与商业荧光蓝色 OLED 相媲美。