有机发光二极管
量子效率
材料科学
电致发光
光电子学
光激发
光化学
激进的
共发射极
二极管
发光
发光二极管
荧光
原子物理学
化学
激发态
纳米技术
光学
物理
有机化学
图层(电子)
作者
H. N. Cho,Sebastian Gorgon,Hsiao‐Chun Hung,Jian Huang,Yuh‐Renn Wu,Feng Li,Neil C. Greenham,Emma Evans,Richard H. Friend
标识
DOI:10.1002/adma.202303666
摘要
Organic radicals have been of interest due to their potential to replace nonradical-based organic emitters, especially for deep-red/near-infrared (NIR) electroluminescence (EL), based on the spin-allowed doublet fluorescence. However, the performance of the radical-based EL devices is limited by low carrier mobility which causes a large efficiency roll-off at high current densities. Here, highly efficient and bright doublet EL devices are reported by combining a thermally activated delayed fluorescence (TADF) host that supports both electron and hole transport and a tris(2,4,6-trichlorophenyl)methyl-based radical emitter. Steady-state and transient photophysical studies reveal the optical signatures of doublet luminescence mechanisms arising from both host and guest photoexcitation. The host system presented here allows balanced hole and electron currents, and a high maximum external quantum efficiency (EQE) of 17.4% at 707 nm peak emission with substantially improved efficiency roll-off is reported: over 70% of the maximum EQE (12.2%) is recorded at 10 mA cm-2 , and even at 100 mA cm-2 , nearly 50% of the maximum EQE (8.4%) is maintained. This is an important step in the practical application of organic radicals to NIR light-emitting devices.
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