High thermoelectric performance in ZrNiSn through electron injection and boosting carrier mobility

Inert insulating oxides have been used as phonon scattering centers to reduce the lattice thermal conductivity of half-Heusler thermoelectric materials, but they often cause a decline in electrical transport performance. In this work, the in-situ conductive semi-metal ZrTe2 makes 15% decreased thermal conductivity and 42% increased electrical conductivity in ZrNiSn simultaneously. When the phase boundary scatters the mid-long wavelength phonons, it is not an obstacle for the electrons. Thanks to the decreased interfacial energy barrier and high mobility electron injection from ZrTe2, even when the charge carrier concentration increases by 56% due to the in-situ ZrTe2 induced bandgap decreasing, 190% improved mobility is also obtained. High zT ∼0.9 is achieved at 873 K in 4 at.% Te composited ZrNiSn through electron injection and boosting carrier mobility. These results have suggested a promising way to decouple the electron and phonon transport behaviors via forming the in-situ conductive secondary phase.