Shin Jin-Wook, Cho Hyunsu, Lee Jonghee, Moon Jaehyun, Han Jun-Han, Kim Kisoo, Cho Seungmin, Lee Jeong-Ik, Kwon Byoung-Hwa, Cho Doo-Hee, Lee Kang Me, Suemitsu Maki, Cho Nam Sung
Opt Express. 2018 Jan 22;26(2):617-626. doi: 10.1364/OE.26.000617.
We propose an effective way to enhance the out-coupling efficiencies of organic light-emitting diodes (OLEDs) using graphene as a transparent electrode. In this study, we investigated the detrimental adsorption and internal optics occurring in OLEDs with graphene anodes. The optical out-coupling efficiencies of previous OLEDs with transparent graphene electrodes barely exceeded those of OLEDs with conventional transparent electrodes because of the weak microcavity effect. To overcome this issue, we introduced an internal random scattering layer for light extraction and reduced the optical absorption of the graphene by reducing the number of layers in the multilayered graphene film. The efficiencies of the graphene-OLEDs increased significantly with decreasing the number of graphene layers, strongly indicating absorption reduction. The maximum light extraction efficiency was obtained by using a single-layer graphene electrode together with a scattering layer. As a result, a widened angular luminance distribution with a remarkable external quantum efficiency and a luminous efficacy enhancement of 52.8% and 48.5%, respectively, was achieved. Our approach provides a demonstration of graphene-OLED having a performance comparable to that of conventional OLEDs.
我们提出了一种利用石墨烯作为透明电极来提高有机发光二极管（OLED）出光效率的有效方法。在本研究中，我们研究了具有石墨烯阳极的OLED中发生的有害吸附和内部光学现象。由于微腔效应较弱，先前具有透明石墨烯电极的OLED的光出射效率几乎未超过具有传统透明电极的OLED。为克服这一问题，我们引入了用于光提取的内部随机散射层，并通过减少多层石墨烯膜中的层数来降低石墨烯的光吸收。随着石墨烯层数的减少，石墨烯-OLED的效率显著提高，有力地表明了吸收的降低。通过使用单层石墨烯电极和散射层获得了最大光提取效率。结果，实现了角亮度分布变宽，外部量子效率显著提高，发光效率分别提高了52.8%和48.5%。我们的方法证明了石墨烯-OLED具有与传统OLED相当的性能。
