Organic light-emitting diodes (OLEDs) based on thermally activated delayed fluorescence (TADF) materials are promising for the realization of highly efficient light emitters. However, such devices have so far suffered from efficiency roll-off at high luminance. Here, we report the design and synthesis of two diboron-based molecules, CzDBA and tBuCzDBA, which show excellent TADF properties and yield efficient OLEDs with very low efficiency roll-off. These donor–acceptor–donor (D–A–D) type and rod-like compounds concurrently generate TADF with a photoluminescence quantum yield of ~100% and an 84% horizontal dipole ratio in the thin film. A green OLED based on CzDBA exhibits a high external quantum efficiency of 37.8 ± 0.6%, a current efficiency of 139.6 ± 2.8 cd A⁻¹ and a power efficiency of 121.6 ± 3.1 lm W⁻¹ with an efficiency roll-off of only 0.3% at 1,000 cd m⁻². The device has a peak emission wavelength of 528 nm and colour coordinates of the Commission International de l´Eclairage (CIE) of (0.31, 0.61), making it attractive for colour-display applications.

基于热活化延迟荧光（TADF）材料的有机发光二极管（OLED）有望实现高效发光体。但是，迄今为止，这种器件在高亮度下会发生效率下降。在这里，我们报告了两个基于二硼硼的分子CzDBA和t BuCzDBA的设计和合成，这些分子显示出出色的TADF性能，并产生了效率非常低的滚降效率的OLED。这些供体-受体-供体（D–A–D）型和棒状化合物同时生成TADF，薄膜中的光致发光量子产率约为100％，水平偶极子比率为84％。基于CzDBA的绿色OLED表现出37.8±0.6％的高外部量子效率，139.6±2.8 cd A ^-1的电流效率功率效率为121.6±3.1 lm W ^-1，在1,000 cd m ^-2时的效率下降仅为0.3％。该设备的峰值发射波长为528 nm，国际照明委员会（CIE）的色坐标为（0.31，0.61），因此对于彩色显示应用很有吸引力。