Nanostructured thermoelectric thin films obtained by wet chemical synthesis

Abstract

Nanostructured pristine lead sulfide and copper iodide semiconductor films as well as copper doped lead sulfide and iodine-enriched copper iodide layers were obtained on solid and flexible substrates via Chemical Bath Deposition (CBD) and Successive Ionic Layer Adsorption and Reaction (SILAR) methods. Crystal structures, optical, electric and thermoelectric properties of the layers have been studied. It was shown that the obtained films deposited on glass and mica substrates are smooth and continuous, have polycrystalline structures of the corresponding bulk semiconductors with grain sizes of several tens of nanometers. Investigations of the optical properties revealed, that their band gaps are characteristic for the corresponding bulk materials. All obtained semiconductor layers are p-type of conductivity. The resistivity of the lead sulphide films were reduced noticeably by means of their doping with copper. Iodination of the copper iodide films convert them into degenerate semiconductors. Investigations of the temperature dependent resistivity, the Seebeck coefficients and power factors confirmed that the obtained materials are promising for their use in thin-film solar thermoelectric generators with the aim of solar heat transforming into electricity.