Multiple-resonance thermally activated delayed fluorescence materials have emerged as promising candidates for next-generation ultrahigh-definition displays due to their narrowband emission and triplet-harvesting capability. However, achieving optimal colour purity and device efficiency for blue multiple-resonance thermally activated delayed fluorescence emitters has presented challenges. Here we demonstrate an effective approach to attain superior deep-blue molecules by constructing twisted-boron-/nitrogen-/oxygen-embedded higher-order fused-ring frameworks with fully resonating structures. The optimized emitter exhibits high rigidity and minimized bonding/antibonding character for ultrasharp emission, along with a small singlet–triplet gap and large spin–orbit couplings for rapid spin flip. This combination results in deep-blue emission at 458 nm with a narrow full-width at half-maximum of 12 nm in solution and a reverse intersystem crossing rate constant of 2.29 × 10⁶ s⁻¹, on par with those of heavy-atom-based multiple-resonance thermally activated delayed fluorescence molecules. The related single-unit organic light-emitting diode achieves an external quantum efficiency of 39.2% with colour coordinates of (0.141, 0.050) and a narrow full-width at half-maximum of 14 nm. Furthermore, a two-unit stacked tandem hyperfluorescence organic light-emitting diode achieves an ultrahigh external quantum efficiency of 74.5% with low efficiency roll-off at high luminance values. This performance represents a remarkable balance between efficiency and colour purity in the deep-blue region, marking an important step towards power-efficient ultrawide-colour-gamut displays.

多重共振热激活延迟荧光材料由于其窄带发射和三重态捕获能力而成为下一代超高清显示器的有希望的候选材料。然而，实现蓝色多重共振热激活延迟荧光发射器的最佳色纯度和器件效率面临着挑战。在这里，我们展示了一种通过构建具有完全共振结构的扭曲硼/氮/氧嵌入的高阶稠环框架来获得优质深蓝色分子的有效方法。优化的发射极表现出高刚性和最小化的键合/反键合特性，可实现超尖发射，同时具有较小的单重态-三重态间隙和大的自旋轨道耦合，可实现快速自旋翻转。这种组合导致在溶液中产生 458 nm 的深蓝色发射，半峰全宽为 12 nm，反向系间窜越速率常数为 2.29 × 10 ⁶ s ^-1 ，与重原子相当基于多重共振热激活延迟荧光分子。相关单体有机发光二极管的外量子效率为39.2%，色坐标为(0.141，0.050)，半峰全宽为14 nm。此外，两个单元堆叠的串联超荧光有机发光二极管实现了74.5%的超高外量子效率，并且在高亮度值下效率滚降较低。这种性能代表了深蓝色区域的效率和色纯度之间的显着平衡，标志着迈向节能超宽色域显示器的重要一步。