Copolymers Based on 1,3-Bis(carbazol-9-yl)benzene and Three 3,4-Ethylenedioxythiophene Derivatives as Potential Anodically Coloring Copolymers in High-Contrast Electrochromic Devices

• Main Authors: Chung-Wen Kuo, Teng-Lu Wu, Yuan-Chung Lin, Jeng-Kuei Chang, Ho-Rei Chen, Tzi-Yi Wu
• Format: Article
• Language: English
• Published: MDPI AG 2016-10-01
• Series: Polymers
• Subjects: electrochromic device; conducting polymer; electrochemical polymerization; optical contrast; coloration efficiency; poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonic acid)
• Online Access: http://www.mdpi.com/2073-4360/8/10/368

In this study, copolymers based on 1,3-bis(carbazol-9-yl)benzene (BCz) and three 3,4-ethylenedioxythiophene derivatives (3,4-ethylenedioxythiophene (EDOT), 3,4-(2,2-dimethylpropylenedioxy)thiophene (ProDOT-Me2), and 3,4-ethylenedithiathiophene (EDTT)) were electrochemically synthesized and their electrochemical and electrochromic properties were characterized. The anodic copolymer P(BCz-co-ProDOT) with BCz/ProDOT-Me2 = 1/1 feed molar ratio showed high optical contrast (ΔT%) and coloring efficiency (η), measured as 52.5% and 153.5 cm2∙C−1 at 748 nm, respectively. Electrochromic devices (ECDs) based on P(BCz-co-EDOT), P(BCz-co-ProDOT), and P(BCz-co-EDTT) as anodic polymer layers, and poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonic acid) (PEDOT-PSS) as cathodic polymer layer were fabricated. P(BCz-co-ProDOT)/triple-layer PEDOT-PSS ECD showed three different colors (light yellow, yellowish-blue, and dark blue) at different applied potentials. In addition, the highest optical contrast (ΔT%) of P(BCz-co-ProDOT)/triple-layer PEDOT-PSS ECD was found to be 41% at 642 nm and the coloration efficiency was calculated to be 416.5 cm2∙C−1 at 642 nm. All ECDs showed satisfactory optical memories and electrochemical cyclic stability.