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为了解聚合物电致光器件(PLED)的电流限制机制,以MEH-PPV为发光材料制作了聚合物电致发光器件,并采用复合阴极结构(LiF/Al)。针对具有不同发光层厚度和阴极修饰层厚度的器件进行电流-电压(I-V)测试分析,结果表明在阴极修饰层(LiF)厚度为2 nm附近时,电流特性以载流子注入限制为主,而在其他厚度时则以载流子输运体限制为主。实验结果还表明,在保持一定电压时,存在一个最优阴极修饰层的厚度,在这个最优厚度下,电子注入特性能够很大程度得到改善。结合不同阴极修饰层厚度的电流特性提出了一个数学试验模型,模拟结果与试验结果较为符合。
In order to understand the current limiting mechanism of PLED, a polymer electroluminescent device was fabricated using MEH-PPV as a luminescent material and a composite cathode structure (LiF / Al) was used. The results of current-voltage (IV) analysis of devices with different thickness of the light-emitting layer and the thickness of the cathode modification layer show that the current characteristics are dominated by the carrier injection when the thickness of the cathode modification layer (LiF) is 2 nm, In other thicknesses, however, carrier-based transporter constraints dominated. The experimental results also show that there is an optimum thickness of the cathode modification layer at a certain voltage, at which the electron injection characteristics can be largely improved. Combined with the current characteristics of different cathode modification thickness, a mathematical model is proposed. The simulation results are in good agreement with the experimental results.