Polythiophenes as parts of ECDs

In this section, the constmction of electrochromic devices whose principle electrochromic materials are polythiophenes is discussed. 3-Substituted polythiophenes are the most popular electrochromic materials for such devices. A solid-state electrochromic device was assembled by using poly[3-[12-(p-methoxyphenoxy)dodecyl]thiophene] and poly(3,4-ethylenedioxythiophene) doped with poly(styrene-sulfonate), which showed a color variation from red in the reduced state to blue in the oxidized state during ca. 500 charge-discharge cycles [80]. 

Reynolds group has made extensive contributions to the device fabrication area using these thiophene-based polymers by obtaining ECDs with high contrast ratios and fast response times by two different approaches materials development and designing dual-type devices [3a, 12, 19]. 

The production of patterned, rapid-switching, reflective ECDs has been demonstrated by Aubert et al. with active electrochromic materials such as PEDOT, (PProDOT) and the dimethyl-substituted derivative PProDOT-Me2, whose resulting switching times were 0.1-0.2 s (5-10 Hz) [51, 56]. In another dual-type polymer PEDOT and PBEDOT-B(OCi2H2s)2 reflective device, a 2 x 2 pixelated lateral configuration has been shown. 

Dual-type polymer electrochromic devices based on copolymers of 2-benzyl-5,12-dihydro-27f-pyrrolo [3, 4 2,3] [1, 4]dioxocino[6,7-6]quinoxaline (DPOQ) and 5,12-dihydrothieno[3, 4 2,3] [1, 4]dithiocino [6,7- ]quinoxaline (DTTQ) with bithiophene were developed. P (DPOQ-co-BT) and P(DTTQ-co-BT) were used as the anodically coloring and PEDOT as the cathodically coloring electrochromic materials [81]. Each device performed with a favorable switching time, optical contrast, open-circuit memory and stability. 

Dual-type absorptive/transmissive polymer electrochromic devices based on poly[thiophen-3-ylacetic acid 4-pyrrol-1-ylphenyl ester (TAPE)-co-A -methylpyrrole (NMPy)] and PEDOT have been assembled, which exhibit good optical memory, stability with moderate switching times and light yellow and green colors upon doping and dedoping, respectively [82], 

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