Fast switching soluble electrochromic polymers obtained from a 4,9-Dihydro-s-indaceno[1,2-b:5,6-b']dithiophene-embedded system

[Display omitted] •Four polymers containing 4,9-dihydro-s-indaceno[1,2-b:5,6-b']dithiophene are successfully synthesized via Stille reaction.•The synthesized polymers are soluble in common organic solvents such as chloroform, dichloromethane, toluene, etc.•Benzo[c][1,2,5]thiadiazole incorporated can greatly improve the switching rate and stability of the polymer films. A series of conjugated polymers containing 4,9-dihydro-s-indaceno[1,2-b:5,6-b']dithiophene (IDT) and 3,4-ethylenedioxythiophene (EDOT) or benzo[c][1,2,5]thiadiazole (Tz) are successfully synthesized via Stille coupling polymerization with reasonable yields as well as high molecular weights. The synthesized polymers can dissolve in chloroform, toluene, THF, etc. Additionally, the physical, optical and electrochemical properties of these synthesized polymers are fully characterized. After a film is spin-coated on the ITO electrode, the prepared polymer films present remarkable electrochromic behaviors. Increasing the composition of electron-rich EDOT along with the conjugated backbone of the synthesized D-A polymer is shown to induce red-shift of the short-wavelength absorption band and blue-shift of the long-wavelength counterpart. On the other hand, as the strong electron-deficient benzo[c][1,2,5]thiadiazole (Tz) incorporates into all-donor polymer mainchain, a new low-energy absorption band due to the intramolecular charge transfer of D-A interaction emerges and the corresponding intensity intensifies with the composition of electron-deficient moieties increasing. In addition, the prepared IDT-based polymers also exhibit fast switching response and good stability.