Principles of thermoelectric devices

In recent years, the use of semiconductor thermojunctions has improved the efficiency of generation by means of the Seebeck effect and has made thermoelectric refrigeration a practical possibility. By using semiconducting compounds of high mean atomic weight, Seebeck coefficients of about 200 μV/° C have been obtained without the ratio of electrical to thermal conductivity departing too far from the value given by the Wiedemann-Franz law for metals. The most favourable semiconductors have been improved still further by alloying with isomorphous materials. Devices employing the thermoelectric effects are discussed.