Thermoelectric properties of a semicrystalline polymer doped beyond the insulator-to-metal transition by electrolyte gating.

Conducting polymer thin films containing inherent structural disorder exhibit complicated electronic, transport, and thermoelectric properties. The unconventional power-law relation between the Seebeck coefficient () and the electrical conductivity (σ) is one of the typical consequences of this disorder, where no maximum of the thermoelectric power factor ( = σ) has been observed upon doping, unlike conventional systems. Here, it is demonstrated that a thiophene-based semicrystalline polymer exhibits a clear maximum of through wide-range carrier doping by the electrolyte gating technique.