Synergistic effects of band engineering and point defect scattering via Te substitution in SnS for thermoelectric applications

Tin sulfide (SnS), a promising material for intermediate-temperature thermoelectric application due to its ultra-low thermal conductivity and high Seebeck coefficient. Owing to the high electrical resistivity, it is challenging to achieve high zT for SnS. Here, the electrical conductivity of SnS can be enhanced by Te substitution prepared through vacuum melting method and tuning the band engineering. Further, the X-ray diffraction confirms the orthorhombic structure of undoped and Te substituted SnS samples without any impurity phases, indicating the high purity of the as–prepared samples. The total thermal conductivity values of Te substituted SnS samples were diminished to 0.32 W/mK at 753 K. In addition, point defect scattering such as mass fluctuation and strain field scattering also plays a significant role in thermal conductivity. Room temperature hall measurement confirms the p-type semiconducting nature of SnS. The band engineering through Te substitution at the sulfur site enhanced the electrical conductivity to 143.77 S/m without distressing the Seebeck coefficient which resulted a peak zT of 0.09 for SnS_0.975Te_0.025 sample at 753 K.