Schmatz Brian, Yuan Zhibo, Lang Augustus W, Hernandez Jeff L, Reichmanis Elsa, Reynolds John R
School of Chemistry and Biochemistry, School of Materials Science and Engineering, Center for Organic Photonics and Electronics, Georgia Tech Polymer Network, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States.
School of Chemical and Biomolecular Engineering, School of Chemistry and Biochemistry, School of Materials Science and Engineering, Center for Organic Photonics and Electronics, Georgia Tech Polymer Network, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States.
ACS Cent Sci. 2017 Sep 27;3(9):961-967. doi: 10.1021/acscentsci.7b00232. Epub 2017 Aug 16.
The ability to process conjugated polymers via aqueous solution is highly advantageous for reducing the costs and environmental hazards of large scale roll-to-roll processing of organic electronics. However, maintaining competitive electronic properties while achieving aqueous solubility is difficult for several reasons: (1) Materials with polar functional groups that provide aqueous solubility can be difficult to purify and characterize, (2) many traditional coupling and polymerization reactions cannot be performed in aqueous solution, and (3) ionic groups, though useful for obtaining aqueous solubility, can lead to a loss of solid-state order, as well as a screening of any applied bias. As an alternative, we report a multistage cleavable side chain method that combines desirable aqueous processing attributes without sacrificing semiconducting capabilities. Through the attachment of cleavable side chains, conjugated polymers have for the first time been synthesized, characterized, and purified in organic solvents, converted to a water-soluble form for aqueous processing, and brought through a final treatment to cleave the polymer side chains and leave behind the desired electronic material as a solvent-resistant film. Specifically, we demonstrate an organic soluble polythiophene that is converted to an aqueous soluble polyelectrolyte via hydrolysis. After blade coating from an aqueous solution, UV irradiation is used to cleave the polymer's side chains, resulting in a solvent-resistant, electroactive polymer thin film. In application, this process results in aqueous printed materials with utility for solid-state charge transport in organic field effect transistors (OFETs), along with red to colorless electrochromism in ionic media for color changing displays, demonstrating its potential as a universal method for aqueous printing in organic electronics.
通过水溶液处理共轭聚合物的能力对于降低有机电子器件大规模卷对卷加工的成本和环境危害具有极大优势。然而，由于以下几个原因，在实现水溶性的同时保持具有竞争力的电子性能颇具难度：（1）具有提供水溶性的极性官能团的材料可能难以纯化和表征；（2）许多传统的偶联和聚合反应无法在水溶液中进行；（3）离子基团虽然有助于获得水溶性，但可能导致固态有序性丧失，以及对任何施加偏压的屏蔽。作为一种替代方法，我们报道了一种多级可裂解侧链方法，该方法结合了理想的水性加工属性而不牺牲半导体性能。通过连接可裂解侧链，共轭聚合物首次在有机溶剂中合成、表征和纯化，转化为水溶性形式用于水性加工，并经过最终处理以裂解聚合物侧链，留下所需的电子材料作为耐溶剂膜。具体而言，我们展示了一种有机可溶性聚噻吩，它通过水解转化为水溶性聚电解质。从水溶液中刮涂后，使用紫外线照射裂解聚合物的侧链，得到一种耐溶剂的电活性聚合物薄膜。在应用中，该工艺可得到用于有机场效应晶体管（OFET）中固态电荷传输的水性印刷材料，以及在离子介质中用于变色显示器的从红色到无色的电致变色，证明了其作为有机电子器件水性印刷通用方法的潜力。
