Highly efficient organic light-emitting diodes from delayed fluorescence
Highly efficient organic light-emitting diodes from delayed fluorescence
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DOI：
10.1038/nature11687
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发表时间：
2012-12-13
期刊：
影响因子：
64.8
通讯作者：
Adachi, Chihaya
中科院分区：
文献类型：
--
作者：
Uoyama, Hiroki;Goushi, Kenichi;Adachi, Chihaya
在过去的二十年里，分子设计所提供的固有灵活性加速了各种有机半导体的发展。特别是，有机发光二极管（OLED）材料的开发取得了巨大进展，从早期的基于荧光分子的器件（1）到使用磷光分子的器件（2，3）。在OLED中，电注入的电荷载流子以1：3的比例复合形成单线态和三线态激子（1）;磷光金属有机络合物的使用利用了通常非辐射的三线态激子，因此提高了整体电致发光效率（2，3）。在这里，我们报道了一类不含金属的有机电致发光分子，其中通过设计（4）使单重态和三重态激发态之间的能隙最小化，从而促进从非辐射三重态到辐射单重态的高效自旋上转换，同时保持高于每秒10（6）次衰变的高辐射衰变率。换句话说，这些分子利用单线态和三线态激子通过荧光衰减通道发光，导致超过90%的内在荧光效率和超过19%的非常高的外部电致发光效率，这与基于高效磷光的OLED（3）中实现的效率相当。
The inherent flexibility afforded by molecular design has accelerated the development of a wide variety of organic semiconductors over the past two decades. In particular, great advances have been made in the development of materials for organic light-emitting diodes (OLEDs), from early devices based on fluorescent molecules(1) to those using phosphorescent molecules(2,3). In OLEDs, electrically injected charge carriers recombine to form singlet and triplet excitons in a 1:3 ratio(1); the use of phosphorescent metal-organic complexes exploits the normally non-radiative triplet excitons and so enhances the overall electroluminescence efficiency(2,3). Here we report a class of metal-free organic electroluminescent molecules in which the energy gap between the singlet and triplet excited states is minimized by design(4), thereby promoting highly efficient spin up-conversion from non-radiative triplet states to radiative singlet states while maintaining high radiative decay rates, of more than 10(6) decays per second. In other words, these molecules harness both singlet and triplet excitons for light emission through fluorescence decay channels, leading to an intrinsic fluorescence efficiency in excess of 90 per cent and a very high external electroluminescence efficiency, of more than 19 per cent, which is comparable to that achieved in high-efficiency phosphorescence-based OLEDs(3).