Fulvenyl-Functionalized Polyisocyanides: Redox-active (Cross-) Conjugated Polymers as Materials for Organic Polymer Batteries and Electrochromic Diodes

该研究项目旨在结合富烯和聚异氰（PIC）的性质，以获得一种新型的可逆氧化还原活性共轭聚合物，可用作有机聚合物电池中的电荷存储材料，或作为电致变色二极管中的氧化还原活性染料。聚异腈是由sp2杂化碳原子的主链组成的形式上共轭的聚合物。然而，聚合物的电子结构使得主链内的碳原子通过单键连接，因此是交叉共轭的。因此，没有观察到通常与扩展共轭相关的电子效应。然而，将氧化还原活性富烯基引入共轭侧链中会破坏聚合物，其中电化学还原或氧化可促进π电子沿着聚合物主链的重新分布，将其转化为完全共轭的聚乙炔样π体系。理想地，这种氧化还原响应将允许可逆地电化学地转换聚合物的颜色，例如从几乎无色到黑色。此外，特定氧化还原活性位点的引入允许聚合物每个重复单元存储多达一（1）个完全电荷。对于最简单的可想到的系统，这对应于高达200-300 Ah/kg的能量密度，这与例如传统的铅/硫酸电池（177 Ah/kg）相比是有利的。资金将主要用于制备新的三-，五-和七-富烯基官能化的PIC，及其物理，光学和电化学表征。有机电子器件的制备将与独立资助的合作伙伴密切合作。

The research project is aimed at combining the properties of fulvenes and polyisocyanides (PICs), in order to access a new type of reversibly redox-active conjugated polymer that may serve as charge storage material in organic polymer batteries, or as redox-active dye in electrochromic diodes. Polyisocyanides are formally conjugated polymers that consist of a backbone of sp2-hybridized carbon atoms. However, the electronic structure of the polymer is such that the carbon atoms within the main-chain are linked by single bonds and are therefore cross-conjugated. As a consequence, electronic effects typically associated with extended conjugation are not observed. However, introduction of redox-active fulvenyl-groups into conjugated side-chains furnishes a polymer in which electrochemical reduction or oxidation may facilitate to a redistribution of the pi-electrons along polymer-backbone, transforming it into a fully conjugated polyacetylene-like pi-system. Ideally, this redox-response will allow to reversibly switch the color of the polymer electro-chemically, e.g. from virtually colorless to black. Furthermore, the introduction of specific redox-active sites allows the polymer to store up to one (1) full charge per repeat unit. For the simplest conceivable systems this corresponds to energy densities of up to 200-300 Ah/kg, which compares favorably e.g. with the classic lead/sulfuric acid battery (177 Ah/kg). Funding will be invested primarily in the preparation of new tria-, penta-, and hepta-fulvenyl functionalized PICs, and their physical, optical, and electrochemical characterization. Preparation of organic electronic devices will be pursued in close collaboration with independently funded cooperation partners.