Electrochromic polymers that change color with an applied voltage can be used in optical displays as well as smart windows and smart mirrors that tint automatically. While such materials are beginning to find commercial applications, new materials are needed in order for smart devices to become widespread.
Jingkun Xu, Jiangxi Science and Technology Normal University, Nanchang, China, and colleagues developed two novel triblock copolymers, containing fluorene (F) and either 3,4-ethylenedioxythiophene (EDOT, pictured) or thiophene (Th) monomers, for use in electrochromic applications. In particular, P(EDOT-F-EDOT) revealed favorable electrochromic performance, showing fast response time and high coloration efficiency. The heterocycle groups (EDOT or Th) reduced the oxidation potential of the monomer, shifting the onset of color change.
P(EDOT-F-EDOT) changed from light gray to blue as the voltage increased, while P(Th-F-Th) changed from yellow to dark green. Additionally, the polymers were stable over long periods. After 500 repeated cycles, around 80 % of the electroactivity was retained for P(EDOT-F-EDOT) and around 90 % was retained for P(Th-F-Th). The variety of colors and high stability make these materials promising for display applications.
- Design and synthesis of 9,9-dioctyl-9H-fluorene based electrochromic polymers,
Qinglin Jiang, Shijie Zhen, Daize Mo, Kaiwen Lin, Shouli Ming, Zhipeng Wang, Congcong Liu, Jingkun Xu, Yuanyuan Yao, Xuemin Duan, Danhua Zhu, Hui Shi,
J. Polym. Sci. Part A: Polym. Chem. 2015.