VO_x作空穴注入层的低启亮电压有机发光二极管

Low Turn-on Voltage Organic Light-emitting-diodes with a Hole-injecting Layer of VO_x

采用真空热蒸发法在ITO阳极与空穴传输层TPD之间插入VOx空穴注入层,使典型结构(ITO/TPD/Alq3/LiF/Al)的有机发光二极管(OLED)的发光性能明显改善。当插入VOx空穴注入层后,器件的启亮电压比没有插入VOx时的器件下降了2 V。当插入20 nm的VOx空穴注入层后,器件的驱动电压在亮度为100 cd/m2或1 000 cd/m2时均下降了3.5 V;器件的最大亮度从5808 cd/m2(14.5 V)上升至9234 cd/m2(11.5 V);器件的最大功率效率从0.88 lm/W增加到2.63 lm/W。此外,对VOx厚度分别为10,20和30 nm的三组器件进行了对比,结果显示器件性能基本一致。

By inserting a high transparent VOx film as the hole-injecting layer between ITO and TPD, the performance of organic light-emitting diodes （OLEDs） with the typical structure of （ITO/TPD/Alq3/LiF/A1） is observably improved. The VOx film was prepared in a conventional high thermal vacuum（〈6 × 10^-4 Pa） evaporation system. It is found that the turn-on voltage of the device with a VOx film as the hole-injecting layer decreased by 2 V compared with that of the device without a VOx layer. Meanwhile, a comparision between the photoelectric characteristics of the device with a 20 nm VOx layer and those of the device without a VOx layer is carried out, and it is found that the operating voltage declines by 3.5 V at 100 cd/m^2 or 1 000 cd/m^2 , the maximum luminance of the device increases from 5 808 cd/m^2 at 14.5 V to 9 234 cd/m^2 at 11.5 V, and the maximum power efficiency of the device increases from 0. 88 lm/W to 2.63 lm/W. In addition, the comparision of the three kinds of devices with a VOx layer of 10, 20 and 30 nm respectively shows that the characteristics of the three devices are in substantial agreement.