Polymer Chemistry

Thermoelectric materials could be applied as thermal power generators to convert heat directly into electrical energy or as a solid state Peltier cooler. In general, traditional thermoelectric materials include alloy such as Bi2Te3, Sb2Te3 PbTe, etc. Recently, conducting polymer-based semiconductors have been gradually receiving much attention as conducting polymers are able to offer many advantages such as low cost, lightweight, flexibility and solution-process fabrication. In addition, conducting polymeric materials with intrinsically low thermal conductivity, which is over two to three orders of magnitude lower than that of commercial inorganic materials, make them as potential candidates for high performance thermoelectric applications. However, the efficiency of conducting polymeric materials is still much lower than that of inorganic counterparts such as Bi2Te3 and Sb2Te3. The thermoelectric performance of a material is usually judged by a dimensionless thermoelectric figure of merit (ZT), which is calculated in terms of ZT = S2σT/κ, where S, σ, T and κ are the Seebeck coefficient, electrical conductivity, absolute temperature and thermal conductivity, respectively. As the thermal conductivity of conducting polymers is usually less than 1 W/mK, much work is focused on how to enhance the electrical conductivity and Seebeck coefficient or how to obtain a proper balance between electrical conductivity and Seebeck coefficient so as to achieve thermoelectric materials with a high ZT value. This presentation will highlight recent advances of highly conductive polymers including poly(3,4ethylenedioxythiophene) and related analogous polymers for thermoelectric applications.