PEDOT:PSS薄膜的光电性能提升、机理研究及其在第三代太阳能电池中的应用

Flexible transparent electrode plays an indispensible role in modern optoelectronic devices. Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) exhibits excellent film-forming properties, transparency and flexibility, thus is potentially to become the next-generation transparent electrode material. However, PEDOT:PSS currently suffers from low electrical conductivity. The project aims to reveal the conductivity limit of PEDOT: PSS thin films through solution treatment, which hopefully could completely remove the excess insulating PSS component in the film. Next, through doping with metal nano-materials, the optical and electrical properties of the PEDOT:PSS film will be further enhanced due to the intrinsically high conductivity and surface Plasmon effect of these metal nano-structures. Furthermore, substrates will undergo physical or chemical treatment to solve the problem of poor adhesion between PEDOT:PSS film and the substrate. The project will study the effects of different dopant materials, solution concentration, treatment temperature and other experimental conditions on the conductivity; then characterize the film structure, PSS distribution as well as optical and electrical properties of treated PEDOT:PSS films, thus understand the microstructure and propose electrical conduction mechanism; and ultimately, explore its potential application as flexible transparent electrodes in third generation solar cells.

柔性的透明电极在现代光学电子元件中扮演着举足轻重的角色。聚(3,4-亚乙二氧基噻吩)-聚(苯乙烯磺酸)(PEDOT:PSS)具备良好的成膜性、透光性和柔性，很有潜力成为下一代透明电极材料。但是PEDOT:PSS目前存在电导率低的问题。本项目拟对PEDOT:PSS薄膜进行溶液处理，通过完全去除薄膜中多余的PSS绝缘组分，力争揭示PEDOT:PSS薄膜的极限电导率。进而通过金属纳米材料掺杂，利用其高导电率和表面等离子共振效应，进一步提升PEDOT:PSS薄膜的光电性能。项目还将对基底进行物理处理或化学改性，解决PEDOT:PSS薄膜与基底的附着力低的问题。项目拟对不同掺杂材料、溶液浓度、处理温度等实验条件对电导率的影响进行研究；进而对薄膜的结构、PSS组分分布、光电特性进行表征，了解其微观形貌并提出导电机制；并最终将其作为柔性透明电极运用在第三代太阳能电池。

本项目为解决导电高分子聚(3,4-亚乙二氧基噻吩)-聚(苯乙烯磺酸)(PEDOT:PSS)电导率低、附着力差的问题，提出了对PEDOT:PSS进行金属纳米材料掺杂和溶液处理的方案，并开展了分子层面的材料性能调控与机理研究。首先，通过有机或无机酸溶液对PEDOT:PSS进行了处理，并研究了不同浓度下各种酸溶液对PEDOT:PSS导电性能的影响。在此基础上，结合表仪器征和分子结构特征讨论了酸处理提高PEDOT:PSS薄膜导电性能的内在机理，为后续的研究提供基础。其次，通过合理的选择酸溶液及掺杂浓度获得了性能优良的柔性透明电极，并成功应用于柔性第三代太阳能电池。再次，在PEDOT:PSS薄膜中原位生成贵金属纳米颗粒的实验中，首次观测到氯铂酸可对PEDOT:PSS同时产生一次掺杂和二次掺杂的效果，获得兼具高电导性和高透光性的PEDOT:PSS透明薄膜，并成功制备了柔性触控屏，实现了成果转化。为了研究PEDOT:PSS与ITO衬底间的相互作用机理，通过超纯水的清洗在ITO表面构建了有序排列的PEDOT:PSS单分子层，利用X射线光电子能谱证明了PSS可通过In-O-S键在ITO表面形成稳定附着，并借助PEDOT+和PSS-间的定向电场提高了基于PEDOT:PSS空穴传输层的钙钛矿太阳能电池的光电性能，最后提出了有序PEDOT:PSS单分子层提高钙钛矿太阳能电池光电性能的理论模型。本项目研究为印刷制备高性能PEDOT:PSS薄膜提供了有效方法，并展示了其在光电器件中的应用潜力。