離子液體對聚(3,4-二氧乙基噻吩)高分子膜電致色變性質之影響

Abstract

In this study, using 1-butyl-3-methylimidazolium hexafluorophosphate ([BMI][PF6]), 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([BMI][TFSI]) and polystyrene sulfonic acid (PSS(aq)) as electrolytes to polymerize the poly(3,4-ethylenedioxythiophene) (PEDOT) films. The purpose was that compare the structure and electrochromic properties of PEDOT films by using different electrolytes. When [BMI][TFSI] and [BMI][PF6] were used as electrolytes for PEDOT polymerization, the HR-SEM images of PEDOT films were network. And the porosity of the PEDOT film from [BMI][TFSI] was larger than the film from [BMI][PF6]. However, we used PSS(aq) to polymerize PEDOT films. The morphology of PEDOT films was dense. Two ionic liquids, [BMI][TFSI] and 1-butyl-3-methylimidazolium dicyanamide ([BMI][DCA]) were used as electrolytes to investigate the electrochromic properties of PEDOT. The result shows that PEDOT polymerized in [BMI][PF6] and switched the oxidation/reduction states in [BMI][DCA] has the best electrochromic properties. Because [DCA] anions size was smaller than [TFSI] anions, [DCA] anions could diffuse in/out the PEDOT film easily and change color completely. After 3900 cycles, the contrast of the film was 41.4%. with a long-term stability of 79%. As [BMI][TFSI] was used as the electrolyte to polymerize PEDOT, [BMI][DCA] also show the higher stability and coloration efficiency. When using PSS(aq) as electrolyte for polymerization to form the dense PEDOT film, the effect of structure of electrolyte on the electrochromic properties is not obvious. The result indicates that the size of anion and the structure of PEDOT are the key factors to influence the electrochromic properties of PEDOT films.