水/醇溶共轭聚合物界面材料及其在光电器件中的应用

Water/Alcohol Soluble Conjugated Polymer Interlayer Materials and Their Application in Solution Processed Multilayer Organic Optoelectronic Devices

相对于传统的无机半导体器件,以有机半导体(特别是聚合物半导体)材料为基础的有机光电器件,可采用与传统印刷技术(例如喷墨打印、卷对卷印刷等)相结合的溶液加工方式制备低成本、大面积、柔性光电器件,因而成为广泛关注的焦点,并得到了快速发展.实现溶液加工的高效有机光电器件的一个关键问题是界面问题——如何避免溶液加工时有机层间的互溶以及如何实现可印刷稳定金属电极的高效电子注入等.水/醇溶性共轭聚合物的迅速发展为解决溶液加工多层有机光电器件所面临的界面问题提供了有效手段.研究发现,水/醇溶共轭聚合物不但可以有效避免溶液加工多层器件中的界面互溶,而且还可与高功函数的稳定金属发生界面偶极相互作用而增强其电子注入,从而解决了高功函数稳定金属电子注入的难题,为实现全溶液加工的高效印刷有机光电器件提供了可行的方案.本文介绍了近年来本课题组在水/醇溶共轭聚合物阴极界面材料及器件应用方面的研究进展,并对水/醇溶共轭聚合物阴极界面材料在聚合物发光二极管和聚合物太阳电池中的工作机理进行了探讨.

Comparing with traditional inorganic semiconductor devices, the organic optoelectronic devices basedon organic semiconductors, especially polymer semiconductors, exhibit several distinct advantages, such as lowcost, light weight, solution processibility, flexibility and compatibility with roll-to-roll printing etc., and havedrawn much attention from both academic and industrial fields. To fulfil solution processed high performanceorganic optoelectronic devices, one of the major challenges is to avoid interface erosion during solutionprocessing as well as to improve the electron injection/extraction between printable high work function metals andactive layers. Water/alcohol soluble conjugated polymers （WSCPs）, which are composed of conjugated backbonesand highly polar side chains, can be processed from water, alcohol and other polar solvents. The unique solubilityof WSCPs provide them with good opportunities to fabricate multilayer organic optoelectronic devices withoutinterface mixing by solution processing, and it is found that WSCPs exhibit promising interface modificationcapability for high work function metal and/or metal oxide electrodes, which can greatly enhance the performanceof organic optoelectronic devices. In this feature article, we gave an overview of our design strategies andachievements on WSCPs, including neutral amine based WSCPs and their quatemized derivatives, WSCPswithout mobile counterions, cross-linkable WSCPs, WSCPs towards large area module device, and theirapplications as interface modification layers in solution processed highly efficient multilayer organicoptoelectronic devices. A brief induction and discussion on working mechanisms of WSCPs serving as cathodemodification layers in polymer light-emitting diodes （PLEDs） and polymer solar cells （PSCs） were also provided.The excellent cathode modification capability of WSCPs can be ascribed to （a） WSCPs decrease the workfunction of cathode to increase the build in potential of devices as well as increase the open voltage （Voc）; （b）WSCPs dope contacted PCBM at the interface to increase the conductivity and improve short-circuit currentdensity （Jsc）; （c） WSCPs exhibit excellent electron-extraction and hole-blocking properties at the interface andincrease the fill factor （FF）.