Conjugated oligothiophenes polythiophene

D. Fichou, G. Horowitz and F. Gamier, Polaron and Bipolaron formation on isolated model thiophene oligomers in solution, Synth. Met., 1990, 39, 125 D. Fichou, G. Horowitz, B. Xu and F. Gamier, Stoichiometric control of the successive generation of radical-cation and dication of extended alpha-conjugated oligothiophenes a quantitative model for doped polythiophene, Synth. Met., 1990, 39, 243. 

Polythiophenes (including oligothiophenes) are one of the most studied and important classes of linear conjugated polymers [444,445], Versatile synthetic approaches to PTs (chemical [446] and electrochemical [447]), easy functionalization and unique, widely tunable electronic properties have been the source of tremendous interest in this class of polymers. 

Radical cations and dications of oligothiophenes have been investigated by many research groups to understand the nature of polarons and bipolarons in polythiophenes which are responsible for the electrical and optical properties of these re-conjugated polymers. 

Longer oligothiophenes such as 6T or higher, give spectra which are very similar to (real) polythiophenes, e.g. a band-gap of around 2.2-2.3 eV This can either be due to a short effective conjugation length of polythiophene or due to defect induced gap-states (X-traps, see below) [ 150]. 

Bauerle, R, and S. Scheib. 1995. Synthesis and characterization of thiophenes, oligothiophenes and polythiophenes with crown ether units in direct tr-conjugation. Acta Polym 46 124—129. 

Infrared and Raman spectra of oligothiophenes and polythiophene have been studied extensively for a long time [92-101]. These spectra are relatively well known and gave rise to force field calculations [94-6]. The vibrational features of these spectra display a strong dependence on conjugation length and some sophisticated theoretical models have been developed in order... 

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