Enhanced thermoelectric properties of Se-doped quasi-one-dimensional van der Waals crystal Ta2PdS6

Recently, quasi-one-dimensional van der Waals crystal Ta2PdS6 has been reported as a promising thermoelectric material with an extraordinarily high power factor. However, element doping to tune the thermoelectric properties has not been studied yet. Here, we systematically investigated the effect of Se doping on the phase composition, charge transport properties and thermoelectric performance of Se-doped Ta2Pd(S1−xSex)6 (x = 0, 0.02, 0.05, and 0.07) polycrystalline bulk materials. Upon doping Se at the S sites to increase the carrier concentration and mobility, the electrical conductivity of Ta2Pd(S0.93Se0.07)6 is dramatically enhanced, while the S is slightly reduced, yielding a significantly improved power factor compared to that of pristine Ta2PdS6. Consequently, Ta2Pd(S0.93Se0.07)6 exhibits a peak ZT of 0.29 at 700 K when the doping content x = 0.07, which is more than twice that of pristine Ta2PdS6.