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

ABSTRACT: Conducting polymer thin films containing inherent structural disorder exhibit complicated electronic, transport, and thermoelectric properties. The unconventional power-law relation between the Seebeck coefficient (S) and the electrical conductivity (?) is one of the typical consequences of this disorder, where no maximum of the thermoelectric power factor (P = S 2?) has been observed upon doping, unlike conventional systems. Here, it is demonstrated that a thiophene-based semicrystalline polymer exhibits a clear maximum of P through wide-range carrier doping by the electrolyte gating technique. The maximum value appears around the macroscopic insulator-to-metal transition upon doping, which is firmly confirmed by the temperature dependence of ? and magnetoresistance measurements. The effect of disorder on charge transport is suppressed in the metallic state, resulting in the conventional S-? relation described by the Mott equation. The present results provide a physical background for controlling the performance of conducting polymers toward the application to thermoelectric devices.

SUBMITTER: Tanaka H 

PROVIDER: S-EPMC7021494 | biostudies-literature | 2020 Feb

REPOSITORIES: biostudies-literature