Effect of energy filtering on Cu2NiSnS4/CuO composites for thermoelectric applications.

Earth-adequate quaternary chalcogenides like Cu2NiSnS4 with more complex crystal structures can become non-toxic and cost-effective thermoelectric (TE) materials. TE materials, by employing the energy filtering effect through appropriate energy bandgap, have enhanced their TE efficiency. The composition of CuO in Cu2NiSnS4 matrix has enhanced the Seebeck coefficient (S) and declined the thermal conductivity (κ) simultaneously, due to the decrement of carrier concentration (n), by increasing the wt% of CuO in the composites. The highest power factor of 270.88 μW m−1 K−2 at 573 K is recorded for 30 wt% composites. The 30 wt% composite material thermal conductivity exhibited a low value of 0.442 W m−1 K−1 through stronger phonon scattering at the interface boundaries formed between the Cu2NiSnS4 matrix and CuO compositions. A maximum zT of 0.35 for the Cu2NiSnS4/30 wt% CuO composite was obtained, 75% larger than that of the Cu2NiSnS4 matrix at 573 K. This strategy of introducing metal oxides into the metal sulphide matrix for obtaining efficient TE performance could be extended to other eco-friendly quaternary chalcogenides. [ABSTRACT FROM AUTHOR]