Weak microcavity effect in tandem white organic light-emitting diodes employing an effective charge-generation layer of Liq/Al/HAT-CN
doi:10.3788/CO.20191202.0382
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摘要:本文使用电荷产生层Liq/Al/HAT-CN制备了蓝黄互补的叠层有机白光器件。通过比较叠层双色器件在相同电流密度下的发光光谱、亮度及电压,阐明了电荷产生层电荷产生及注入过程,并进一步研究了双层结构Liq/Al。在10 mA/cm 2电流密度下,叠层白光器件的工作电压为8.3 V,亮度为746 cd/m 2,分别为蓝光单节器件(4.2 V,315 cd/m 2)与黄光单节器件(4.2 V,426 cd/m 2)之和,证明了电荷产生层的有效性。当电流密度为240 mA/cm 2时,叠层白光器件获得最高亮度11 420 cd/m 2,在1 000 cd/m 2的亮度下,电流效率为7.2 cd/A,功率效率为2.6 lm/W。驱动电流密度从10 mA/cm 2增加到30 mA/cm 2时,蓝光成分比例仅增加5%,证明器件发光性能稳定。针对叠层器件中存在的弱微腔效应,根据微腔理论,通过光学模拟计算进行了深入研究,模拟结果与实际光谱高度吻合,说明了光学模拟计算的准确性。
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关键词:
- Liq/Al/HAT-CN/
- 电荷产生层/
- 叠层有机白光器件/
- 弱微腔效应
Abstract:A charge generation layer(CGL) of Liq/Al/HAT-CN is used to fabricate the blue-yellow complementary tandem white organic light-emitting device. A group of dual-color devices are used to illustrate the working mechanism of CGL, and Liq/Al structure in the CGL is further studied. Under the current density of 10 mA/cm 2, the operating voltage(8.3 V) and luminance(746 cd/m 2) of the tandem device are both approximately the sum of those of blue device(4.2 V, 315 cd/m 2) and yellow device(4.2 V, 426 cd/m 2), respectively, confirming that the charge generating layer is effective. The maximum brightness of 11 420 cd/m 2is obtained at the current density of 240 mA/cm 2, and the current efficiency and power efficiency are 7.2 cd/A and 2.6 lm/W under the luminance of 1 000 cd/m 2, respectively. When driving current density increases from 10 mA/cm 2to 30 mA/cm 2, the ratio of blue light in spectra increases by 5%, which means the stable performance of device. In view of the weak microcavity effect existing in the tandem device, we conducted in-depth research by optical simulation based on the microcavity theory. The simulation results are highly consistent with the actual spectra, demonstrating the accuracy of optical simulation calculation. -
表 1Luminous characteristics of the monochromatic device and the tandem device at current densities of 10 mA/cm2and 20 mA/cm2.
Table 1.Luminous characteristics of the monochromatic device and the tandem device at current densities of 10 mA/cm2and 20 mA/cm2.
Voltage/V
J=10/20
(mA/cm2)Luminance/(cd·m-2)
J=10/20
(mA/cm2)DPVBi 4.2/4.5 315/603 Rubrene 4.2/4.6 426/763 Tandem white 8.3/8.9 746/1 378 -
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