Synthesis and electrochromic properties of oligothiophene derivatives

In order to develop novel organic electrochromic materials, oligothiophene derivatives, 5,5″-biformyl-2,2′:5′,2″-terthiophene (OHC-3T-CHO) and 2,3,4,5-tetrathiopenyl-thiophene (X-T), were synthesized. Three electrochromic devices have been fabricated using OHC-3T-CHO and XT, and the electrochromic properties of OHC-3T-CHO and X-T were studied. The indium-tin-oxide (ITO)/OHC-3T-CHO/electrolyte solution/ITO device exhibited reversible, clear colour change from yellow to bright bluish-green on electrochemical doping and dedoping, while ITO/OHC-3T-CHO/conducting gel/ITO device and ITO/OHC-3T-CHO/conducting filter paper/ITO device exhibited colour change from yellow to green. The ITO/XT/electrolyte solution/ITO device showed reversible, clear colour change between yellowish orange and silver-gray on electrochemical doping and dedoping.