Doctoral Dissertations

Date of Award

8-2016

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Materials Science and Engineering

Major Professor

Bin Hu

Committee Members

Roberto S. Benson, David J. Keffer, Zhanhu Guo

Abstract

Thermoelectric phenomena involve the simultaneous presence of both electrical and thermal currents. The entropy has been heavily used as the driving force to diffuse charge carriers between high and low temperature surfaces towards the development of Seebeck effects in thermoelectric devices. However, this driving force from entropy difference can cause an inverse relationship between Seebeck coefficient and electrical conductivity in the thermoelectric developments. Increasing the charge density can decrease the entropy difference to diffuse the charge carriers at a given temperature difference and lead to a decrease on the Seebeck coefficient developed by the entropy difference. Therefore, it is necessary to develop an additional driving in thermoelectric devices for development of Seebeck effect. In this dissertation, Chapter 1 presents an introduction to the concepts of thermoelectric effect, the widely-utilized organic materials in thermoelectric devices, and the peer publication review in order to cover the academic progress in this field. Meanwhile, the fundamental issues towards developing Seebeck effect is also discussed in this chapter. Chapter 2 studies the additional driving force of surface polarization to enhance Seebeck effect in vertical multi-layer metal/polymer/metal thin-film devices. Chapter 3 explores tunable Seebeck regimes between entropy and polarization differences based on vertical multi-layer electrode/organic/electrode thin-film devices. Chapter 4 studies conflicting problems in developing dual Seebeck and cooling effects in vertical organic thin-film devices by considering about the surface polarization effect from charge-phonon coupling. Chapter 5 focuses on using Seebeck effects to study n and p-type properties in organo-metal halide perovskites. Finally, Chapter 6 gives a short conclusion for the entire dissertation.

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