Simultaneously achieving both a high efficiency and long lifetime in deep-blue organic light-emitting diodes is challenging. Here we report thermally activated delayed fluorescence (TADF) organic light-emitting diodes that aim to meet this goal by combining a new design of blue TADF materials with a triplet-exciton recycling protocol. Two TADF materials, one distributing and one emitting, were doped into a host to form triplet-exciton-distributed TADF devices. The singlet excitons were transferred from the host to the emitter via the distributing TADF material by cascade energy transfer, whereas the triplet excitons were transferred to the emitter as singlet excitons by a triplet-exciton recycling process between the low-triplet-energy host and the distributing TADF material. The resulting triplet-exciton-distributed TADF devices achieved a high external quantum efficiency of 33.5 ± 0.1, a colour coordinate corrected current efficiency over 400 cd A^–1, a lifetime of >5,000 h and a y colour coordinate below 0.10.

在深蓝色有机发光二极管中同时实现高效率和长寿命具有挑战性。在这里，我们报告了热激活延迟荧光 (TADF) 有机发光二极管，旨在通过将蓝色 TADF 材料的新设计与三重态激子回收协议相结合来实现这一目标。将两种 TADF 材料（一种分布材料和一种发射材料）掺杂到主体中以形成三重态激子分布的 TADF 器件。单重态激子通过分布的 TADF 材料通过级联能量转移从主体转移到发射极，而三重态激子通过低三重态能量主体和低三重态能量主体之间的三重态激子循环过程作为单重态激子转移到发射极。分发 TADF 材料。^–1，寿命 >5,000 小时和y颜色坐标低于 0.10。