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本文利用无机材料ZnO作为空穴缓冲层,制备了结构为ITO/ZnO/NPB/Alq3/Al的有机电致发光器件。用计算机控制的KEITHLEY2400-PR655系统测量器件的电压-电流-亮度特性。研究结果表明,当ZnO薄膜的厚度为2 nm时,器件的电流效率可达1.65 cd/A,最大亮度为3 449 cd/m2;而没有加入缓冲层的同类器件,最大亮度仅为869.7 cd/m2,最大电流效率为0.46 cd/A。由此可以看出,加入ZnO空穴缓冲层后,最大亮度提高3.97倍,最大电流效率提高3.59倍。分析认为适当厚度的ZnO薄膜降低了发光层空穴的浓度,提高了电子和空穴的复合率,从而降低了电流密度,提高了器件的电流效率,改善了器件性能。
In this paper, an organic electroluminescent device with ITO / ZnO / NPB / Alq3 / Al structure was prepared by using inorganic ZnO as hole buffer layer. The voltage-current-brightness characteristics of the device are measured with a computer controlled KEITHLEY 2400-PR655 system. The results show that when the thickness of ZnO thin film is 2 nm, the current efficiency of the device can reach 1.65 cd / A and the maximum brightness is 3 449 cd / m2. Without the buffer layer, the maximum brightness is only 869.7 cd / m2, the maximum current efficiency of 0.46 cd / A. It can be seen, adding ZnO hole buffer layer, the maximum brightness increased 3.97 times, the maximum current efficiency increased 3.59 times. The analysis shows that the ZnO thin films with the appropriate thickness reduce the hole concentration of the light-emitting layer, increase the recombination rate of electrons and holes, thereby reducing the current density, improving the current efficiency of the device and improving the device performance.