The production and investigation of antimony based thin films for energy applications

Unlike the materials commonly used in thin-film photovoltaic technologies, Sb2S3 films promise a high potential in energy applications with their unique properties such as containing abundant and non-toxic elements, stability and high absorption coefficient. However, theoretically predicted efficiency values cannot be reached for Sb2S3 based photovoltaic solar cell devices. High optical band gap and high electrical resistivity values are the main reasons for this. The motivation of this Ph.D. thesis is to add Cu and Bi metals into the Sb2S3 structure by applying new and alternative methods in the production process and to find solutions for the high optical band gap and high electrical resistivity problems of Sb2S3 film, which is known as an emerging material for solar cell technologies. It is aimed to obtain Cu or Bi containing Sb2S3 films with a two-stage process. In the first stage, the precursor coatings were obtained by thermal evaporation method, and in the second stage, these precursor coatings were subjected to heat treatment for an effective metal diffusion in a furnace in sulfur atmosphere. Precursor coatings for Cu-containing Sb2S3 films were prepared in Cu/Sb2S3 form and the initial heat treatment temperature was determined as the key parameter. In addition, precursor coatings prepared in two different geometries as bi-layer form of Bi/Sb2S3 and multi-layer form of Bi/Sb2S3 (5 layers) were subjected to heat treatment in a sulfur atmosphere at different temperatures (180, 200, 220, 240 and 260 ◦C) and Bi containing Sb2S3 films were obtained. Analyses were performed by Energy Dispersive X-ray Spectroscopy, X-ray Diffraction, Raman spectroscopy, Atomic Force Microscopy, Scanning Electron Microscopy and Four-Probe Technique to investigate the effect of incorprating Cu and Bi metals and selected initial parameters on the physical properties of Sb2S3 films. As a result of the analyses and evaluations carried out, it has concluded that the properties of Sb2S3 films containing Cu and Bi can be improved by using parameters such as initial heat treatment temperature and precursor coating geometry during metal incorpration processes, and outputs of this study may be a solution to common problems such as high optical bandgap and high electrical resistivity value of Sb2S3 films.