微腔效应对顶发射串联蓝光有机电致发光器件性能的影响

Influence of microcavity effect on the performance of top emission tandem blue organic light emitting devices

相比于传统有机电致发光器件,串联有机电致发光器件的发光效率与寿命均得到明显提升.因此,深入研究微腔效应对顶发射串联有机电致发光器件性能的影响具有重要意义.本文以蓝光器件为例,通过光学仿真模拟与实际实验相结合的方法,研究了顶发射串联蓝光器件的光学性能与电学性能变化规律.具体实验为:分别制备了顶发射串联蓝光器件,使其两个发光层位置分别位于器件光学结构中的第一与第二反节点、第二与第三反节点、第三与第四反节点.分析并确定了顶发射串联蓝光器件的两个发光层位置分别位于第二反节点与第三反节点处时,器件性能较佳.即:当器件电流密度为15 mA/cm^2时,器件电流效率为10.68 cd/A(色坐标CIEx,y=0.14,0.05),其亮度衰减到95%所需时间为1091.55 h.可能原因是:器件腔长较长时,既可以改善第一发光单元的空穴与电子平衡度、削弱表面等离激元效应,降低膜厚波动性对器件腔长的影响性;又可以在一定程度内起到包裹Partical的作用,提高效率,延长寿命.这一研究成果为设计高效率、长寿命的顶发射串联器件提供了重要依据.

Comparing with traditional single organic light-emitting device(OLED),the luminance efficiency and lifetime of tandem OLED are significantly improved.Therefore,it is of crucial importance to in depth study the influence of microcavity effect on the performance of top emitting tandem OLED.In this paper,taking the blue organic light emitting device for example,the change rule of optical and electrical properties of top-emitting tandem blue-light device are studied by combining optical simulation with practical experiments.The specific experiment is as follows.The top emitting tandem blue organic light devices are fabricated,in which the two light-emitting layers are located at the first anti node and second anti node,the second anti node and third anti node,and the third anti node and fourth anti node in the optical structure of the device respectively.It is found that the performance of the device is better when the two emitting layers of the top-emitting tandem blue light device are located at the second anti node and third anti node in the optical structure of the device respectively.That is to say,when the current density of the device is 15 mA/cm^2,the current efficiency of the device reaches10.68 cd/A,color coordinate(CIEx,y)of the device is(0.14,0.05),and the time of the brightness decreases from 100%to 95%in 1091.55 hours,which is likely to be due to the fact that when the cavity length of the device is long,it can not only improve the recombination rate of hole and electron in the first light-emitting unit,weaken the surface plasmon polarition effect,reduce the influence of the fluctuation of the film thickness on the cavity length of the device,but also play a role of wrapping partials to a certain extent,improve the efficiency and prolong the device lifetime.The research results provide an important theoretical and data basis for designing the top-emitting tandem blue light device with high efficiency and long lifetime.In the future,we will continue to systematically and detailedly study the top emitting tandem organic light-emitting devices,which will provide strong support for preparing the laminated devices with high efficiency long-lifetime,and lower cost.