Combination of Carrier Concentration Regulation and High Band Degeneracy for Enhanced Thermoelectric Performance of CuSbSe.

The effect of Al-, Ga-, and In-doping on the thermoelectric (TE) properties of CuSbSe has been comparatively studied on the basis of theoretical prediction and experimental validation. It is found that tiny Al/Ga/In substitution leads to a great enhancement of electrical conductivity with high carrier concentration and also large Seebeck coefficient due to the preserved high band degeneracy and thereby a remarkably high power factor. Ultimately, coupled with the depressed lattice thermal conductivity, all three elements (Al/Ga/In) substituted samples have obtained a highly improved thermoelectric performance with respect to undoped CuSbSe. Compared to the samples at the same Al/In doping level, the slightly Ga-doped sample presents better TE performance over the wide temperature range, and the CuSbGaSe sample presents a record high ZT value of 0.9 among single-doped CuSbSe at 623 K, which is about 80% higher than that of pristine CuSbSe. This work offers an alternative approach to boost the TE properties of CuSbSe by selecting efficient dopant to weaken the coupling between electrical conductivity and Seebeck coefficient.