Thermoelectric Transport Theory in Organic Semiconductors

Abstract

The thermoelectric effect is hopefully a technique that can convert heat from the sun, industrial sectors and automobile exhausts to power energy. Due to current issues on energy production and the environment, the thermoelectric effect has recently become the subject of growing interest. Organic semiconductors are one kind of excellent material which exhibit the various thermoelectric characteristics based on the complexity of molecule structures with the relatively low thermal conductivities demanded for high thermoelectric performance. In this chapter, we will systemically describe the thermoelectric transport theory of organic semiconductors in detail. In Section 2.1, we will introduce the development of organic semiconductors, the transport mechanism of organic semiconductors, and the concept of the thermoelectric transport effect. In Section 2.2, the basic thermoelectric transport equations will be discussed, including the Boltzmann transport equation, Mott's expression and the general expression of the Seebeck effect. In Section 2.3, based on first-principles theory, the hopping transport theory, the percolation theory, the hybrid theory, the thermoelectric transport characteristics will be discussed in detail, respectively. In Section 2.4, based on Monte Carlo simulation, comparisons between the numeric and the analytical results of the Seebeck effect will be discussed. Finally, the future outlook of thermoelectric transport theory is briefly discussed in Section 2.5.