介质覆盖Ag阴极的顶发射有机发光二极管出光效率增强机制及耦合表面等离子体激元研究  

Mechanism Study and the Role of Coupled Surface Plasmon Polaritons in Optical Out-coupling Enhanced Top-emitting OLEDs with a Dielectric Capped Ag Cathode

作　　者：王学良 钱敏 WANG Xueliang;QIAN Min(Department of Electronic Science and Technology,School of Electronic and Information Engineering,Soochow University,Suzhou,Jiangsu 215006,China;School of Optical and Electronic Information,City University of Suzhou,Suzhou,Jiangsu 215104,China)

机构地区：[1]苏州大学电子信息学院电子科学与技术系,江苏苏州215006 [2]苏州城市学院光学与电子信息学院,江苏苏州215104

出　　处：《光子学报》2022年第9期96-108,共13页Acta Photonica Sinica

基　　金：江苏省高校自然科学基金(No.19KJD510006)。

摘　　要：采用经典的光学传输矩阵法和微腔理论计算具有不同厚度的功能有机薄膜和电极形式的顶发射有机发光二极管光学的耦合出光效率。根据仿真计算结果,制备了绿色荧光Alq_(3)顶发射器件并进行了相关测试。研究发现,采用银作为半透明阴极并蒸镀NPB有机覆盖层,相对于无覆盖层的器件来说,出光效率大大增强,该增强效应采用近场光学理论的偶极子辐射与银电极相互作用理论,即耦合表面等离子体激元理论,解释为是金属Ag薄膜阴极增强的透射、变化的微腔增益以及最主要的出光银阴极上的耦合表面等离子体激元效应三个因素的综合作用。In the field of Organic Light-Emitting Diode(OLED)display application,most manufacturing companies have made a transition to TEOLED technology,due to the nearly 100%aperture rate of Thin Film Transistor(TFT)driven Active Matrix OLED(AMOLED).TEOLEDs can be fabricated on any solid substrates like silicon wafers or glasses.A TEOLED is constructed using a semi-transparent top cathode such as ITO or Ag thin film and a reflective bottom metal anode.ITO is a perfect transparent anode material.It may be used as cathode.ITO’s work function,however,is fairly high,which does not suit electron injection,decreasing the performance of the device.Other problematic issues in using ITO include indium,a very scarce and expensive element,sputtering that damages the organic functional layer,and brittleness which cannot be used in flexible devices.Hence,it is important to explore alternative cathode.Ag is often used as a replacement of ITO for its relatively high optical transparency and good ductility.In general,a dielectric with a high refractive index is deposited on the surface of the metal cathode to promote the out-coupling efficiency.It has been reported that the light extracting efficiency will be increased if an Ag cathode is coated by index matching materials such as inorganic ZnSe,ZnS,MgF_(2),SiO_(2),ITO,ZnO,TiO_(2),organic Alq_(3),NPB,BCP and so on.The degree of enhancement varies widely with different types of material and thicknesses.Some researchers did the transmittance measurement for cathode with different thicknesses of a capping layer,and found that,despite the transmittance through the cathode being at the maximum value,the total device light extracting efficiency is far from the optimal value and sometimes just the opposite.Leo,et al.showed that this efficiency enhancement was mainly due to low absorption and high reflection,which lead to a high extraction because of the micro-cavity effect.Another paper argued that the enhancement of the efficiency is closely related to suppression of Surface Plasmon Polarito

关 键 词：顶发射有机发光二极管 透明银阴极 覆盖层 表面离子体激元效应 微腔效应 

分 类 号：TN383.1[电子电信—物理电子学]