A sketch for super-thermoelectric materials

Improving the dimensionless figure of merit ( zT ) is the everlasting goal for thermoelectrics. With the discovery of super-thermoelectric materials, which exhibit much higher zT s (arbitrarily say, zT > 5) than that of the traditional materials, it is possible to dramatically alter the landscape of the thermoelectric applications. Identifying super-thermoelectric materials is extremely challenging based on the current understanding of electron and phonon transport. It is interesting to wonder if it is possible to predict how the super-thermoelectric material might look like before it has been discovered. Herein, band modeling on the thermoelectric properties is conducted. It is concluded that super-thermoelectric materials should have a much lower optimal carrier concentration than the “golden carrier concentration” (in the range between 10 19 and 10 20 cm −3 ). In addition, the super-thermoelectric materials should also have a much larger optimal Seebeck coefficient than that of the existing materials (∼200 μV K −1 ). Based on these predictions, potential issues i.e. , on the development of super-thermoelectric materials are discussed. Finally, predictions on the super-thermoelectrics beyond the band modeling are also briefly discussed. • Super-thermoelectric materials should have much higher performance ( e.g. , zT > 5) than that of the traditional materials. • Super-thermoelectric materials should exhibit a lower optimal electron concentration than that of the traditional thermoelectric materials. • Super-thermoelectric materials should have an improved optimal Seebeck coefficient (>200 μV K −1 ).