Thermoelectric properties of nanocrystalline Cu3SbSe4 thin films deposited by a self-organized arrested precipitation technique

In the present investigation, tetragonal p-type stannite group member Cu3SbSe4 has been successfully synthesized in an aqueous alkaline medium using a self organized arrested precipitation technique (APT). The deposited thin films were characterized by UV-Vis spectrophotometry, X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The thermoelectric figure of merit (ZT) is investigated by the measurement of the electrical conductivity, Seebeck coefficient and thermal conductivity of deposited thin films. On the basis of experimental details, the reaction mechanism is also discussed in detail. Optical absorption spectra show direct allowed type transition with a band gap energy of 1.96 eV. XRD results indicate that APT is a favourable technique to synthesize pure Cu3SbSe4 thin films having a tetragonal crystal structure. FESEM and HRTEM micrographs of Cu3SbSe4 show spherically diffused granular morphology having an average grain size of 40 nm. EDS and XPS spectra confirm the presence of Cu, Sb and Se elements in the composition. The compact nature leads to a higher electrical conductivity and a smaller grain size of the material leads to lower thermal conductivity in thin films, so that a promising ZT value is obtained at room temperature (0.2 at 300 K). The present work provides a new method to engineer efficient thermoelectric material for power generation in an effective manner.