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
References
- Zotti, G.; Salmaso, R.; Gallazzi, M.C.; Marin, R.A.; In Situ Conductivity of a Polythiophene from a Branched Alkoxy-Substituted Tetrathiophene. Enhancement of Conductivity by Conjugated Cross-Linking of Polymer Chains. Chemistry of Materials 1997, 9, 791-795, 10.1021/cm960476a.
- Thanasamy, D.; Jesuraj, D.; Konda kannan, S.K.; Avadhanam, V.; A novel route to synthesis polythiophene with great yield and high electrical conductivity without post doping process. Polymer 2019, 175, 32-40, 10.1016/j.polymer.2019.03.042.
- Li, W.; Wang, X.; Zhang, B.; Chen, Y.; In Situ Modification of Multi-Walled Carbon Nanotubes with Polythiophene-Based Conjugated Polymer for Information Storage. Materials 2023, 16, 908, 10.3390/ma16030908.
- Fabre, B.; Trifluoroborate-substituted polythiophene as a novel conjugated polymer promising for sensing and solid-state reactions. Electrochemistry Communications 2001, 3, 549-552, 10.1016/s1388-2481(01)00215-6.
- Bredas, J.L.; Heeger, A.J.; Theoretical investigation of gas-phase torsion potentials along conjugated polymer backbones: polyacetylene, polydiacetylene, and polythiophene. Macromolecules 1990, 23, 1150-1156, 10.1021/ma00206a038.