Enhanced light out-coupling of organic light-emitting devices using embedded low-index grids
Enhanced light out-coupling of organic light-emitting devices using embedded low-index grids
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DOI：
10.1038/nphoton.2008.132
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发表时间：
2008-08-01
期刊：
影响因子：
35
通讯作者：
Forrest, Stephen R.
中科院分区：
文献类型：
--
作者：
Sun, Yiru;Forrest, Stephen R.
由于有机发光器件的高效率，应用有机发光器件来降低室内照明的能耗（现在每年的成本超过2300亿美元）正引起人们的兴趣。实际上，具有100%的内部量子效率η（IQE）的电致磷光有机发光器件（参考文献2、3）已经接近荧光灯的效率（4-6）。然而，由于有机材料的高折射率以及由此产生的光学限制和内反射，常规有机发光器件的光耦合输出效率η（out）被限制为类似于20%（参考文献2、7）。在这里，我们证明了嵌入一个低折射率的网格在有机层可以增强波导光的耦合输出，而不会产生光谱失真。当与耦出玻璃模式的微透镜组合时，白色有机发光器件的外量子效率η（EQE）和功率效率提高到34 +/-2%和68 +/-4 lm W-1。所得的eta（out）是用作对比的常规有机发光器件的2.3 +/-0.2倍，并且模拟表明增强可以进一步增加到3.4 +/-0.2。
The application of organic light-emitting devices to reduce the energy consumption of interior lighting, which now costs more than $230 billion annually, is attracting interest due to the high efficiency of these devices. Indeed, electrophosphorescent organic light-emitting devices with an internal quantum efficiency eta(IQE) of 100% ( refs 2,3) already approach the efficiency of fluorescent lamps(4-6). However, because of the high refractive index of organic materials and the optical confinement and internal reflection that results, the light out-coupling efficiency eta(out) for conventional organic light-emitting devices is limited to similar to 20% (refs 2,7). Here we demonstrate that embedding a low-index grid in the organic layers can enhance the out-coupling of the waveguided light without spectral distortion. When combined with microlenses that out-couple the glass modes, the external quantum efficiency eta(EQE) and power efficiency of a white organic light-emitting device are improved to 34 +/- 2% and 68 +/- 4 lm W-1. The resulting eta(out) is 2.3 +/- 0.2 times that of a conventional organic light-emitting device used as a comparison, and simulations indicate that the enhancement can be further increased to 3.4 +/- 0.2.