Enhancement of the Thermoelectric Figure of Merit in Blended Cu₂Sn_1–xZn_xS₃ Nanobulk Materials

Among the promising waste heat harvesting technologies, thermoelectric materials and devices have attracted considerable interest in recent decades because they offer a promising route to convert waste heat into electrical power. The Cu2Sn1–xZnxS3 system consists of green and abundant elements and exhibits modest thermoelectric performance at a relatively low temperature range. However, the thermoelectric figure of merit, ZT, of Cu2Sn1–xZnxS3 is still too low for practical applications. This study encompasses the bottom-up wet chemical synthesis of Cu2Sn1–xZnxS3 nanoparticles with varying Zn compositions. By blending Cu2Sn0.85Zn0.15S3 and Cu2Sn0.9Zn0.1S3 nanoparticles in a weight fraction of 9:1 to make a nanobulk material, we could achieve a maximum ZT value of 0.64 at 670 K, which is 1.7 and 1.9 times higher than the ZT values of the pristine Cu2Sn0.85Zn0.15S3 and Cu2Sn0.9Zn0.1S3 nanobulk materials, respectively.