Thermoelectric figure-of-merit under large temperature differences

The dimensionless thermoelectric figure-of-merit, ZT, of Bi2Te3 based alloys was investigated under a large temperature difference using a recently reported 'open/short circuit' measurement technique. It is shown that the measured ZT decreases with an increase in temperature difference. Theoretical analysis indicates that this dependence can be explained by taking into account the Thomson effect. An equation is obtained for a modified thermoelectric figure-of-merit which is valid for measurement over large temperature differences.