The development of luminescent organic radicals has resulted in materials with excellent optical properties for near-infrared emission. Applications of light generation in this range span from bioimaging to surveillance. Although the unpaired electron arrangements of radicals enable efficient radiative transitions within the doublet-spin manifold in organic light-emitting diodes, their performance is limited by non-radiative pathways introduced in electroluminescence. Here we present a host–guest design for organic light-emitting diodes that exploits energy transfer with up to 9.6% external quantum efficiency for 800 nm emission. The tris(2,4,6-trichlorophenyl)methyl-triphenyl-amine radical guest is energy-matched to the triplet state in a charge-transporting anthracene-derivative host. We show from optical spectroscopy and quantum-chemical modelling that reversible host–guest triplet–doublet energy transfer allows efficient harvesting of host triplet excitons.

发光有机自由基的发展已经产生了具有优异的近红外发射光学性能的材料。光产生在该领域的应用涵盖从生物成像到监视。尽管自由基的不成对电子排列能够在有机发光二极管的双重态自旋流形内实现有效的辐射跃迁，但它们的性能受到电致发光中引入的非辐射路径的限制。在这里，我们提出了一种有机发光二极管的主客体设计，该设计利用能量转移，800 nm 发射的外部量子效率高达 9.6%。三(2,4,6-三氯苯基)甲基-三苯胺自由基客体与电荷传输蒽衍生物主体中的三线态能量匹配。我们通过光谱学和量子化学模型表明，可逆的主客体三重态-双重态能量转移可以有效地收获主体三重态激子。