Poly(thieno[3,4-b]-1,4-oxathiane) and poly(3,4-ethylenedioxythiophene-co-thieno[3,4-b]-1,4-oxathiane)/poly(styrene sulfonic sodium): Preparation, characterization, and optoelectronic performance

Abstract

In this work, the asymmetrical analog of 3,4-ethylenedioxythiophene (EDOT), thieno[3,4-b]-1,4-oxathiane (EOTT), was synthesized and chemically polymerized first in aqueous solution using poly(styrene sulfonic sodium) (PSS) as the polyelectrolyte to yield poly(thieno[3,4-b]-1,4-oxathiane) (PEOTT)/PSS. As-formed film exhibited low electrical conductivity (∼10−4 S/cm). Alternatively, EOTT together with EDOT (in different molar ratio of 1:1 and 1:5) was copolymerized and the polymer poly(EOTT-co-EDOT)/PSS had electrical conductivity of 10−1 S/cm. After dimethyl sulfoxide (DMSO) treatment, the electrical conductivity was enhanced to 100 S/cm; however, the conductivity of the above homopolymer was reduced (∼10−5 S/cm). Raman spectroscopy was used to interpret conductivity enhancement or reduction after DMSO treatment. The conductivity decrease of PEOTT/PSS compared to poly(EOTT-co-EDOT)/PSS may arise from the conformational change of PEOTT backbone from the quasi-planar to the distorted planar mode induced by PSS–/PSSH through ionic interaction. Kinetic studies revealed that the copolymer had high coloration efficiencies (375 cm2/C), low switching voltages (−0.8 to +0.6 V), decent contrast ratios (45%), moderate response time (1.0 s), excellent stability, and color persistence. An electrochromic device employing poly(3-methylthiophene) and poly(EOTT-co-EDOT)/PSS as the anode and cathode materials was also studied. From these results, poly(EOTT-co-EDOT)/PSS would be a promising candidate material for organic electronics. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 2285–2297