柔性量子点复合薄膜及其电致发光器件的弯折性能

Bending performance of flexible quantum dot composite films and their electroluminescent device

近年来,可弯曲的柔性电子器件引起了人们广泛的关注,但器件的性能稳定性和弯折稳定性阻碍了其实际应用。本文通过对柔性量子点发光二极管(QLED)施加弯折作用力,着重探究QLED弯折前后功能薄膜及器件性能的变化。通过调控QLED的弯折曲率半径,测试得到薄膜参数和器件电学性能。利用有限元方法对不同弯折半径下的聚对二甲酸乙二醇酯-氧化铟锡(PET-ITO)复合透明电极进行分析,结果显示随着弯曲曲率半径的减小,ITO电极会出现更明显的应力集中现象。对其进行形貌表征和方阻测试表明过度弯折会使电极材料出现损伤,方块电阻增大。电导率测试结果表明弯折行为会减弱电荷的传导能力。利用瞬态电致发光光谱(TREL)技术对弯折前后的器件进行了表征,结果表明弯折曲率半径的减小,降低了电极上电荷传输的效率,同时较小的弯折曲率半径会导致内部缺陷的增加,降低器件内部载流子的注入与传输效率,对器件的性能造成影响。

In recent years,bendable flexible electronic devices have attracted widespread attention,but the performance stability and bending stability of the devices have hindered their practical applications.In this paper,we focus on the changes of functional film and device performance before and after bending of flexible quantum dot light-emitting diodes(QLEDs)by applying bending force to QLEDs.The film parameters and device electrical properties were tested by regulating the bending radius of QLEDs.The polyethylene terephthalate-indium tin oxide(PETITO)composite transparent electrodes with different bending radii were analyzed by the finite element method,and the results show that as the bending radius decreases,the ITO electrode shows a more obvious stress concentration phenomenon.The morphological characterization and square resistance tests show that excessive bending will cause damage to the electrode material and increase the square resistance.Transient electroluminescence spectroscopy(TREL)was used to characterize the devices before and after bending.The results show that the decrease in the bending radius of curvature reduces the efficiency of charge transfer on the electrode,and the smaller bending radius of curvature leads to the increase of internal defects,which reduces the efficiency of carrier injection and transfer inside the device and affects the performance of the device.