Thermoelectric Properties of Polymer-Semiconductor-Polymer Molecular Junction

DOI: 10.1615/IHTC15.tel.009360
pages 7979-7987

Yuanyuan Wang
Shanghai Polytechnic University

Huaqing Xie
School of Science, College of Art and Science, Shanghai Polytechnic University, No. 2360 Jinhai Rd. Pudong District, Shanghai, 201209, China

KEY WORDS: Thermoelectric, molecular junction, small polaron model, Landauer formula

Abstract

There has been an increasing interest in thermoelectric (TE) properties of nanoscale organic-inorganic structures recently since it is possible to enhance thermopower due to the effect of quantum effect and to reduce thermal conductivity due to low thermal conductivity in organic materials. In this work, we studied the TE properties of polymer-semiconductor-polymer naoscale junction, where a semiconductor quantum dot (QD) is trapped between two polymer leads. In this molecular junction, the sharp density of states (DOS) give us a possibility to enhance the TE performance. We found that the TE properties are strongly affected by the energy mismatch between the polymer leads and the QD, which can be tuned by two gate voltages flexibly. We use Holstein small polaron model to describe the transport in the polymer leads since the strong electron-phonon interaction in polymers beyond the perturbation theory. The Green's function method along with the Landauer formula is then applied to calculate the TE properties of a nanoscale PSP junction. The results obtained in this work can provide a new possibility to achieve good TE performance based on nanoscale hybrid junction structure.