The Thermoelectric Figure of Merit and its Relation to Thermoelectric Generators†

The expression for the figure of merit of a semi-conductor of given carrier mobility and lattice thermal conductivity expressed in terms of generalized Fermi-Dirae functions has been numerically evaluated for various scattering indices. The results are presented graphically enabling the maximum figure of merit to be found. High-temperature limitations due to minority carrier production are considered in relation to the energy gap of the semi-conductor. The results are discussed in connection with bismuth telluride and other sulphides, selenides and telluridos of the heavy metals.