Morphological modulation to improve thermoelectric performances of PEDOT:PSS films by DMSO vapor post-treatment

Abstract

The thermoelectric performance of poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) films are optimized by dimethyl sulfoxide (DMSO) vapor post-treatment on the basis of DMSO addition in PEDOT:PSS solution. Compared with pristine films, the electrical conductivity of PEDOT:PSS with 5% DMSO films is increased by two orders of magnitude. When the PEDOT:PSS with 5% DMSO films are subjected to DMSO vapor post-treatment, the electrical conductivity and Seebeck coefficient are further enhanced. As a result, the power factor of 60 min treated PEDOT:PSS with 5% DMSO films is twice larger than the one without DMSO vapor treatment. Microscopical investigations reveal the morphological evolution of the DMSO vapor treated films. After certain of treating time, quite even and uniformed film morphology is developed, which indicates that film micro-structural order is improved. Through the study of carrier concentration by optical absorption spectra and XPS, it is confirmed that the improvements of thermoelectric performances are attributed to the enhancement of carrier mobility.