Impact of non-stoichiometry in the thermoelectric performance of polyol method prepared Cu1+xIn1−xS2 (x = −0.3, −0.2, −0.1, 0, 0.1, 0.2) nanowires

Abstract

A significantly enhanced thermoelectric power factor at 320 K in a facile polyol method prepared non-stoichiometric Cu1+xIn1−xS2 (x = −0.3, −0.2, −0.1, 0, 0.1, 0.2) nanowires with traces of Cu2S has been demonstrated here. Rietveld refinement of powder XRD and Raman analysis confirm these. Field effect scanning electron microscopy (FESEM) study shows micron size CuInS2 spherical particles made up from 8.8 nm diameter with about 35 nm length nanowires. The dramatic increase in electrical conductivity and hence thermoelectric performance with increasing x is attributed to the formation of defects, Cu2S, and increase in carrier concentrations. The power factor reaches a high of 0.8 μW m−1 K−2 at 320 K and an electrical conductivity of 2800 S/m, which is about 35 and 250 times higher, respectively, than that of pure CuInS2 and hot-pressed Bi2S3 nanorods respectively at this temperature. These results expect high-power factor improvement for power production in the future.