A first-principles study of the Nernst effect in doped polymer

Abstract

Since the discovery of the Nernst effect in 19th century, it has been an important transverse thermoelectric charge transport phenomenon in solid states. Conjugated polymers have recently attracted great attention as promising optoelectronic materials. However, the Nernst effect is yet to be explored for conducting polymers. Here, we report the first theoretical investigations of the Nernst effect in doped conducting polymers by first-principles calculations under the frame work of Fermi-liquid theory. Specifically, the Nernst coefficients of PBTTT are found to be ranging from 0.0029 to 0.039 µV K−1 T−1. They are monotonically decreased with the doping level due to both much enhanced Fermi energy and the decreased charge mobility at high doping level. Our theoretical findings not only enhance our fundamental understanding of the doping mechanism that controls the charge transport properties of conducting polymers, but more importantly, they also offer initial predictions of the transverse thermoelectric conversion capability of conducting polymers. These predictions are crucial for the development of future flexible thermoelectric applications based on the Nernst effect.