Electro-optical properties of poly[di(2-thiophenyl)carborane] and its opto-electronic application

• Electrochromic properties of a carborane based conjugated polymer were reported.
• The polymer exhibited an ambipolar character and multicolor behaviors.
• It is the first electrochromic device based on a carborane unit.

Electrochemical and optical properties of a hybrid carborane based polymer called poly(di(2-thiophenyl)carborane) (P1) obtained electrochemically were reported as well as its electrochromic device application. Thiophene donor units and m-carborane acceptor unit were combined under the same umbrella via donor–acceptor–donor approach to obtain di(2-thiophenyl)carborane (1). Contrary to the literature, extreme conditions like highly dried solvent or inert atmosphere were not used for polymerization and characterization. Polymer P1 has an ambipolar character since it exhibited a reversible oxidation peak at a half wave potential (E1/2) of 1.08 V and a quasi reversible reduction peak at E1/2 = −1.82 V vs. Ag/AgCl. The polymer film has an optical band gap of 1.95 eV with a maximum absorption band centered at 488 nm. Also, it exhibited multicolor electrochromic behavior between its reduced and oxidized states changing from dark orange to light blue. Furthermore, the electrochromic device prepared based on P1 film was stable and robust.

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