Evaluation of Thermoelectric Properties of Polythiophene Films Synthesized by Electrolytic Polymerization

Polythiophene films were synthesized by electrolytic polymerization, and the synthetic parameters and their thermoelectric properties, i.e., Seebeck coefficient and electric conductivity, were investigated in detail. The Seebeck coefficient tended to decrease with increasing electric conductivity. However, the thermoelectric power factor increased with electric conductivity, and was 1.03 x 10(-5) W.m(-1).K-2 at 23 mu V.K-1 and at 201 S.cm(-1). This value is large compared with those of other conductive polymers, and the figure of merit reached to one thirty against Bi-Te system. In addition, the elaborated surface morphology and internal structure, i.e., crystallinity, of the films were also evaluated by scanning electron microscopy, X-ray diffraction, and elemental analysis, and the relationship between thermoelectric properties and structure was discussed. (C) 2009 The Japan Society of Applied Physics DOI: 10.1143/JJAP.48.071501