Polythiophene electrochromic displays

Conducting polymers such as polyacetylene, polypyrrole, polyaniline, polythiophene, etc. have been actively studied for use in various fields due to their interesting properties batteries,46 electrochromic displays,47 materials for supercapacitors,48 corrosion protection,49 protecting layers for static electricity,50 materials for organic electroluminescence displays,51 sensing materials,52 etc. Polypyrrole is reported to be extremely rigid, with a semi-crystalline structure. 

An electrochromic display (BCD) is a thin solid state device that changes color reversibly when subjected to a small electrical potential. Since the doping processes of certain conducting polymers are accompanied by changes in the color, this effect has been conveniently exploited in the realization of BCD devices. Thin films of a conducting polymer polythiophene, for example, are red in the doped state and deep blue in the undoped state. 

The alteration of the optical properties for an electrochromic material involves the insertion or extraction of charge. These polymers can be classified into three types, depending on their specific optical states (1) absorption/transmission-type materials made of metal oxides, viologens or polymers such as PEDOT, including at least one colored and one bleached state for smart windows, (2) display-type materials made of polythiophenes without a transmissive state and (3) materials composed of blends, laminates and copolymers including more than two colored states [7],... 

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