Achieving higher thermoelectric performance for p-type Cr2Ge2Te6 via optimizing doping

Cr2Ge2Te6-based compounds with a layered structure and high symmetry hold a great promise for thermoelectric applications. Our studies have been committed to improve their electrical properties considering the low power factor of only ∼0.23 mW/mK2 in pristine samples. In this work, various doping contents on the site that has less influence on the charge-conducting band have been investigated to enhance the power factor. The results show that Fe-doping is the most favorable among elements we applied. According to the first-principles calculation, the Fe doping on the Cr site leads to the increment of the density of states around the Fermi level. By tuning the carrier concentration via Fe doping, the peak power factor rises from 0.23 mW/mK2 to 0.37 mW/mK2 and zT rises from 0.3 to 0.4 at 830 K for Cr1.9Fe0.1Ge2Te6 along the pressing direction. These results shed lights for designing high performance thermoelectric materials.