采用真空蒸镀法分别制备了以CuPc、ZnPc、C60为阴极修饰层的OLED, 对比研究了它们对OLED光电性能的影响。从能级结构、表面形貌、折射率及纳米界面等方面对载流子注入和输运进行了探讨。结果表明: 修饰层使器件性能显著提高, 它不仅降低OLED开启电压(最低至4.2 V)、提高OLED电流密度及发光效率(最高至13.49 lm/W), 同时增强了器件的发光稳定性(180 s后光强保持在90%以上), 其中以CuPc为阴极修饰层的器件表现的性能最好。发光光谱方面, 以CuPc和ZnPc作为修饰层的器件对550~650 nm的红光部分略有吸收, 而C60作为修饰层的器件光谱则无太大变化, 这是由修饰层材料的吸收系数随不同波长而变化所致。实验结果说明, 若想较大程度地提高器件电性能, 酞菁材料是不错的选择; 若对光谱有要求, 可用C60做阴极修饰层。

Different materials(CuPc, ZnPc, C60) were used as the cathode buffer layers in typical OLED(ITO/TPD/Alq3/Al) prepared by evaporation, respectively. The influences of those materials on electroluminescence characteristics were investigated and relative mechanisms were discussed. Energy level structure, surface morphology, refractive index, nano-interface and some other mechanisms were used to discuss the injection and transportation of carriers. It is found that the buffer layers can evidently improve the devices performances: not only decrease the drive voltage(to 4.2 V), but also increase the current density and efficiency(to 13.49 lm/W), as well as enhance the stability(the intensity remained above 90% after 180 s). Device with CuPc layer achieves the best performance. Besides, CuPc and ZnPc cathode buffer layers show strong absorbing properties on OLEDs spectrum between 550 nm and 650 nm, while C60 layer did not exhibit this effect. This is because the absorption coefficient of each material corresponds to different wavelengths. The results explain that CuPc and ZnPc cathode buffer layers could commendably improve OLEDs characteristics, while fullerene(C60) is a good choice if there is a strict request on spectrum.