Preparation and Thermoelectric Property of n-type SnS

Abstract

SnS composed of low toxicity, low-cost and earth-abundant elements, has extensive attention in the field of thermoelectric research. The n-type SnS1-xClx (x=0, 0.02, 0.03, 0.04, 0.05, 0.06) polycrystalline bulk thermoelectric samples were prepared by mechanical alloying (MA) combined with Spark Plasma Sintering (SPS). Effect of Cl- amounts on the phase structure, microstructure and thermoelectric transport properties were systematically studied. Results show that introduction of Cl- enhances electron concentration which makes intrinsic p-type SnS change to n-type. With the amount of Cl- increasing, the Hall carrier concentration of n-type SnS semiconductor increases from 6.31×1014 cm-3 (x=0.03) to 7.27×1015 cm-3 (x=0.06) at room temperature. The maximum electrical conductivity of 408 S∙m-1 and the relatively high Seebeck coefficient of -553 μV∙K-1 are obtained at 823 K for x=0.05 sample, which produces the maximum power factor of 1.2 μW•cm-1•K-2. Addition of Cl- can introduce point defects to scatter phonons, which makes the lattice thermal conductivity reduce from 0.67 W•m-1•K-1 (x=0) to 0.5 W•m-1•K-1 (x=0.02). The highest ZT~0.17 is obtained at 823 K for x=0.04 sample, which is 70% higher than that (ZT~0.1) of the pristine SnS.