Rational band engineering and structural manipulations inducing high thermoelectric performance in n-type CoSb3 thin films

Owing to the earth-abundancy, eco-friendliness and high thermoelectric performance, CoSb3 skutterudites have been employed in thermoelectric devices with a high energy conversion efficiency. However, the thermoelectric performance of CoSb3-based thin films is still relatively low within the medium temperature range. In this work, we report a record high ZT of similar to 0.65 at 623 K in the n-type Ag/In co-doped CoSb3 thin films, fabricated by a facile magnetron sputtering technique. Extensive characterizations and computational results indicate both Ag and In as fillers prefer to occupy the interstitial sites in the CoSb3 lattice. A 0.2% Ag doping induces impurity states in the band structure of CoSb3, boosts the density-of-states near the Fermi level and enhances the absolute Seebeck coefficient up to similar to 198 mu V K-1. Simultaneously, a 4.2% In doping further tunes the bandgap, increases the electrical conductivity up to similar to 75 S cm(-1), and contributes to an optimized power factor of similar to 2.94 mu W cm(-1) K-2 at 623 K. In addition, these interstitial dopants accompanying with dense grain boundaries contribute an ultra-low thermal conductivity of similar to 0.28 W m(-1) K-1 at 623 K, leading to a high ZT in the film system. This work demonstrates that rational band engineering and structural manipulations can achieve high performance in n-type CoSb3-based thin films, which possess full potential for applying to miniature thermoelectric devices.

Automated summary

A record high ZT value of 0.65 at 623K was achieved in n-type Ag/In co-doped CoSb3 thin films, demonstrating high thermoelectric performance. Ag and In fillers prefer to occupy the interstitial sites in the CoSb3 lattice, inducing impurity states in the band structure and tuning the bandgap to enhance electrical conductivity and reduce thermal conductivity.