Red-to-black electrochromism of 4,9-dihydro-s-indaceno[1,2-b:5,6-b’]dithiophene-embedded conjugated polymers

General Description

A series of 4,9-dihydro-s-indaceno[1,2-b:5,6-b′]dithiophene-based conjugated polymers with 3,4-bis(dodecyloxy)thiophene, 3,3-bis((dodecyloxy)methyl)-3,4-dihydro-2H-thieno[3,4-b] [1, 4] dioxepine and 3,4-ethylenedioxythiophene as co-monomers were synthesized via Stille coupling reaction in more than 50 % yields. These polymers possess relatively high number-average molecular weights of 14,900–21,000 g mol−1 and exhibit good solubility in common organic solvents. The physical and electrochemical properties of these polymers were studied, and the polymers showed optical bandgap between 2.04 and 2.08 eV. Electrochromic devices showed a rare and reversible colour change between dark red at neutral state and black at oxidized state with optical switching contrast ratios of up to 50 % at λ max and 90 % at 1500 nm in the visible and NIR regions, respectively.

4,9-dihydro-s-indaceno[1,2-b:5,6-b’]dithiophene-based conjugated polymers showing rare and reversible colour change between dark red at neutral state and black at oxidized state were synthesized via Stille coupling. These polymers possess high optical contrast in both the visible and NIR regions.

Conclusions

Four 4,9-dihydro-s-indaceno[1,2-b:5,6-b']dithiophene-embedded (IDT-based) polymers with EDOT or Tz moieties are synthesized via Stille coupling polymerization. Due to the long alkyl groups in the IDT units, the synthesized polymers can dissolve in common organic solvents such as chloroform, toluene, tetrahydrofuran, etc. In addition, electrochromic properties of these IDT-containing polymers are fully investigated via spectroelectrochemical method.

References:

[1] YONGQIANG PANG . Fast switching soluble electrochromic polymers obtained from a 4,9-Dihydro-s-indaceno[1,2-b:5,6-b’]dithiophene-embedded system[J]. Synthetic Metals, 2018, 242: Pages 29-36. DOI:10.1016/j.synthmet.2018.04.009.