Polythiophene is a conjugated polymer built from thiophene rings linked at the 2- and 5-positions. The overlap of the pi orbitals along the chain gives it an extended conjugation, and oxidation or reduction produces mobile charge carriers [1]. The unsubstituted polymer is insoluble and infusible, so alkyl side chains are attached to the 3-position to make it processable [2]. The regioregularity of those side chains controls how the chains stack, and a head-to-tail arrangement gives the highest conductivity [3]. Doping shifts the absorption from the visible into the near infrared, which underlies the electrochromic behaviour [4]. The conductivity falls on exposure to air because the doped state is oxidatively unstable, so encapsulation is needed for a stable device [5].
- conjugated polymer
- thiophene ring
- regioregularity
- doping
- electrical conductivity
- alkyl side chain
- electrochromism
Conducting polymers and applications·Polymers and Plastics·Materials Science·Physical Sciences
References
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