Electronic Structure and Thermoelectric Prospects of Phosphide Skutterudites

TL;DR

This study uses first principles calculations to explore the electronic structure and thermoelectric potential of phosphide skutterudites, highlighting the effects of La filling on their electronic properties and thermopower.

Contribution

It demonstrates that La filling can open a band gap in phosphide skutterudites, providing insights into their potential for thermoelectric applications.

Findings

La filling opens a band gap in LaFe_4P_12.

Stoichiometric CoP_3 is metallic unlike arsenide and antimonide counterparts.

N-type La filled skutterudites may have better thermoelectric properties.

Abstract

The prospects for high thermoelectric performance in phosphide skutterudites are investigated based on first principles calculations. We find that stoichiometric CoP_3 differs from the corresponding arsenide and antimonide in that it is metallic. As such the band structure must be modified if high thermopowers are to be achieved. In analogy to the antimonides it is expected that this may be done by filling with La. Calculations for LaFe_4P_12 show that a gap can in fact be opened by La filling, but that the valence band is too light to yield reasonable p-type thermopowers at appropriate carrier densities; n-type La filled material may be more favorable.