The local potential variation mapping including thermoelectromotive force in nanocomposite materials under non-thermal equilibrium

Abstract

Thermoelectric nanocomposite materials are attracting much attention due to their high thermoelectric performance brought by effectively combining thermoelectric properties of the matrix and introduced nanostructures. However, understanding the mechanism of Seebeck coefficient enhancement brought in nanocomposite materials is difficult because there are no measurement methods of thermoelectromotive force V TE on the nanoscale. In this study, we demonstrate that the controlled temperature gradient Kelvin force microscopy (T-KFM) measurement we developed in 2021 can be applied to nanocomposite films. We observe temperature difference ΔT-induced vacuum level V vac variation, which is related to V TE, in PEDOT:PSS/Si nanowire nanocomposite films using T-KFM. The large ΔT-induced V vac variation at the tops of Si nanowires is generated, which is mainly explained by the larger Seebeck coefficient value of the Si nanowire. This application of T-KFM to the nanocomposites highlights that T-KFM will be a powerful tool for the development of nanocomposite materials with controlled thermoelectric properties on the nanoscale.