空穴传输层的厚度对石墨烯基有机发光二极管性能的影响

Effects of the Thickness of the Hole Transport Layer on the Performance of Graphene-based Organic Light-emitting Diodes

以石墨烯作为透明阳极、以1,1-双[4-[N,N-二(对甲苯基)氨基]苯基]环己烷(TAPC)作为空穴传输层,用蒸镀法构建柔性绿光OLED器件,研究了蒸镀速率对TAPC层形貌的影响和TAPC层的厚度对器件性能的影响。先控制蒸镀速率分别为0.05、0.1和0.15 nm·s^(-1)制备了厚度为60 nm的TAPC膜层,蒸镀速率为0.05 nm·s^(-1)的TAPC膜层其表面粗糙度(2.52 nm)最低。随后在保持其他材料层厚度不变的情况下,以0.05 nm·s^(-1)的蒸镀速率分别制备了厚度为50、60、70和80 nm的TAPC膜层并构建了OLED器件。对比研究发现,TAPC层厚度为70 nm的器件性能最佳,其最大亮度达到34350 cd·m^(-2),最高外量子效率(EQE)达到21.02%。该器件还具有优异的柔韧性,是色坐标位于(0.3140,0.6386)的标准绿光OLED器件。

Thickness modulation is an important way to improve the performance of organic light-emitting diode(OLED)device.In this paper,flexible green OLED devices were constructed by vacuum thermal evaporation,using graphene as the transparent anode and 1,1-bis[4-[N,N-bis(p-tolyl)amino]phenyl]cyclohexane(TAPC)as the hole transport layer.The effects of evaporation speed on the morphology of the TAPC layer and the thickness of TAPC layer on the device performance were studied.First,60 nm-thick TAPC layers were fabricated by controlling the evaporation speed at 0.05,0.1 and 0.15 nm·s^(-1).It was found that the TAPC film had the lowest surface roughness of~2.52 nm when the evaporation speed was 0.05 nm·s^(-1).Subsequently,TAPC layers with thicknesses of 50,60,70 and 80 nm were fabricated at a evaporation speed of 0.05 nm·s^(-1)and OLED devices were fabricated while keeping the thickness of other functional layers unchanged.A comparative study showed that the device with 70 nm-thick TAPC layer achieved the highest performance with a maximum brightness of 34350 cd·m^(-2)and a maximum external quantum efficiency(EQE)of 21.02%.Meanwhile,the device has excellent flexibility and the CIE chromaticity coordinate is located at(0.3140,0.6386),which is very close to the chromaticity coordinate of standard green light.This study is significant for promoting the application of flexible graphene-based OLEDs in the fields of display and lighting and for the development of wearable optoelectronic devices.