Poly thiophene as a Redox System

The oxidized (doped) form of PBT can be reduced (dedoped) reversibly by controlling the potential of the polymer coated electrode. The redox process is accompanied by a drastic change in the properties of the polymer (e.g. PBT), such as electrical conductivity (cf. Sect. 3.2.3, BU4NCIO4), stability (cf. Sect. 4.3, the doping/dedopping degree), color (cf. Sect. 3.4.3), optical properties (cf. Sect. 3.5) and wettability (see Sect. 3.11) [217,261-263]. The reversible redox behavior of PT depends on the monomer concentration [264,265]. PT films electrochemically formed in solutions of 0.4 M thiophene have reversible redox behavior, in contrast to PT films formed in 0.01 M solutions of thiophene. This is explained by overoxidation due to the limited transport of the monomer by 

Poly(isothianaphthene) (PITN) can be reversibly cation- and anion-doped without decomposition of the material. PITN with these two reversible and stable redox states of different colors is a potential candidate for electrochromic displays. The reversible redox reaction of PITN and the existence of a relatively stable residual charge can be used in electronic devices, such as memories with learning effect (reading-writing device) [253]. 

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