2.1 Standard thermoelectric couple and module construction

A single thermoelectric couple is constructed from two 'pellets' of semiconductor material usually made from bismuth telluride (Bi2Te3), as this material has been found to show the most pronounced thermoelectric effects around room temperature. One of these pellets is doped with acceptor impurity to create a p-type pellet, the other is doped with donor impurity to produce an n-type pellet. The two pellets are physically linked together on one side, usually with a small strip of copper, and mounted between two ceramic outer plates that provide electrical isolation and structural integrity. A single thermoelectric couple, as shown in Figure 1, is generally of limited practical use, as the rate of useful power generated due to the Seebeck effect is very small. Practical thermoelectric modules are constructed with several of these thermoelectric couples connected electrically in series and thermally in parallel, with modules typically containing a minimum of three thermoelectric couples, as shown in Figure 2, rising to 127 couples for larger devices [5].
