Enhanced thermoelectric performance of hydrothermally synthesized CuFeS2 nanostructures by controlling the Cu/Fe ratio

Abstract

In this manuscript, low-cost chalcopyrite (CuFeS2) nanostructures as a potential thermoelectric material are explored. CuxFe1-xS2 (x = 0, 0.1, 0.3 & 0.5) samples were fabricated by simple hydrothermal route. X-ray diffraction pattern reveals the formation of CuFeS2 along with impurity phases of FeS, FeO, and FeS2. The presence of these unwanted impurity phases goes on decreasing while the improvement in phase purity of CuFeS2 was observed with the increase in Cu concentration. This improvement in phase purity leads to enhancement in the Seebeck coefficient from 69 to 92 μV/°C (at 25 °C) by increasing the Cu concentration. Hall measurement reveals the significant enhancement of the electrical conductivity values from 90 to 110 S/cm by increasing the Cu concentration. The enhancement in electrical conductivity was associated with the shifting of Cu/Fe stoichiometry that leads to the generation of more free carriers which leads to a high-power factor value up to 9.31 × 10−5 W/mK2. To support our results, some other supplementary measurements such as Raman spectroscopy and scanning electron microscopy were also performed.