Enhancement of thermoelectric properties of CoSb3 based skutterudites by double filling of Tl and In
Thermoelectric (TE) generators can directly generate electrical power from waste heat, and thus could be an important part of the solution to future power supply and sustainable energy management. The main obstacle to the widespread use of TE materials in diverse industries, e.g. for exhaust heat recovery in automobiles, is their low efficiency in converting heat to electricity. The conversion efficiency of TE materials is quantified by the dimensionless figure of merit, ZT, and the way to enhance ZT is to decrease the lattice thermal conductivity (klat) of the material, while maintaining a high electrical conductivity, i.e. to create a situation in which phonons are scattered but electrons are unaffected. Here, we report skutterudites filled by Tl and In, Tl0.1InxCo4Sb12, which allow a dramatic reduction of klat, yielding a ZT of 1.2 at 700 K. We demonstrate that the reduction of klat is due to the effective phonon scattering induced both by the rattling of Tl and In and by the naturally formed In2O3 n.