High efficiency and low voltage p-i-n top emitting organic light-emitting devices
High efficiency and low voltage p-i-n top emitting organic light-emitting devices
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DOI：
10.1117/12.617008
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发表时间：
2005-08
期刊：
影响因子：
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通讯作者：
Qiang Huang;K. Walzer;M. Pfeiffer;G. He;K. Leo;M. Hofmann;T. Stübinger;Martin Vehse
中科院分区：
文献类型：
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作者：
Qiang Huang;K. Walzer;M. Pfeiffer;G. He;K. Leo;M. Hofmann;T. Stübinger;Martin Vehse
我们推出高效、低压顶发射有机发光二极管 (OLED)，其阳极和阴极采用相同的材料 (Ag)。得益于掺杂电荷载流子注入和传输层（p-i-n 结构），尽管顶部发射 OLED 中电极的功函数和传输材料的 HOMO/LUMO 位置不一致，但二极管表现出与类似底部发射 OLED 相当甚至更好的电特性。展示了具有 Ir(ppy)3 掺杂双发射层 (D-EML) 的绿色顶发射 OLED，在 1000 cd/m2 亮度下显示出 50 cd/A 的效率，同时 1000 cd/m2 需要仅 2.85 V 的极低驱动电压。通过在阴极顶部放置额外的有机覆盖层，可以调整器件的光学结构，并且可以进一步提高二极管的效率，在亮度为 1000 cd/m2 时最高效率可达 78 cd/A。使用相同的封端策略，高效磷光红色和荧光蓝色顶部发射 OLED 的效率在 1000 cd/m2 下分别高达 13.6 cd/A 和 8.6 cd/A。
We present highly efficient, low voltage top emitting organic light-emitting diodes (OLEDs) employing the same material (Ag) for both anode and cathode. Benefiting from doped charge carrier injection and transport layers (p-i-n structure) the diodes show comparable or even better electric characteristics than similar bottom emission OLEDs although the work function of the electrodes in the top emission OLEDs and the HOMO/LUMO location of the transport materials do not coincide. A green top emitting OLED with an Ir(ppy)3 doped double emission layer (D-EML) is demonstrated showing an efficiency of 50 cd/A at a brightness of 1000 cd/m2 and at the same time needing a very low driving voltage of only 2.85 V for 1000 cd/m2. By putting an additional organic capping layer on top of the cathode, the optical structure of the device can be tuned and the efficiency of the diodes can be further improved to a maximum efficiency of 78 cd/A at a brightness of 1000 cd/m2. Using the same capping strategy, efficient phosphorescent red and fluorescent blue top emitting OLEDs are demonstrated with efficiencies at 1000 cd/m2 as high as 13.6 cd/A and 8.6 cd/A, respectively.