Flexible conjugated polyfurans for bifunctional electrochromic energy storage application

The development of high-efficiency organic electronic energy storage materials is a necessary prerequisite for modern intelligent and environmentally friendly devices. Given that polymer molecular structure is always closely related to its arrangement conformation, morphological attributes and performances. Here, we electrodeposited and characterized series poly(2,2′-bifuran) (P2Fu), poly(2,2′:5′,2′'-terfuran) (P3Fu), and poly(2,2′:5′,2′':5′',2′''-quaterfuran) (P4Fu) based furan heterocycle to understand the molecular structure induce the changes of optical and electronic properties. As expected, flexible free-standing films were polymerized at low potential with improved stability. By virtue of its favorable electronic structure and inherent electrochromic, the tailored P4Fu reveals its potential for dual-function electrochromic-supercapacitor (DES) applications via systematic cyclic voltammetric and galvanostatic techniques, showing noticeable multicolor, high coloration efficiency (CE) of 330.5 cm2 C-1, and high specific capacitance (241.6F g−1/1.0 A g−1), which are much attractive than those of polythiophene derivatives, even superior to the heterocyclic counterparts. This is also the first time to explore the DES application potential of polyfuran. Furthermore, a DES device was successfully assembled by using P4Fu as the activation layers, which can monitor the energy storage level through color conversion. The research demonstrates an important step toward environmentally compatible electronics, and provides novel green material options for high-available organic smart devices.