Production and characterization of Cu2SnS3 films for solar cell applications: The effect of the sulfurization temperature on CuS secondary phase


Ketenci Ozsoy E., Atay F., Buyukgungor O.

SOLAR ENERGY, vol.214, 2021 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 214
  • Publication Date: 2021
  • Doi Number: 10.1016/j.solener.2020.11.068
  • Journal Name: SOLAR ENERGY
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, PASCAL, Aerospace Database, Applied Science & Technology Source, Communication Abstracts, Compendex, Computer & Applied Sciences, Environment Index, Geobase, INSPEC, Metadex, Civil Engineering Abstracts
  • Keywords: Cu2SnS3, Sulfurization temperature, Thermal evaporation, CuS secondary phase, Absorber layer, THIN-FILMS, OPTICAL-PROPERTIES, METALLIC PRECURSORS, FABRICATION, DEPOSITION
  • Eskisehir Osmangazi University Affiliated: Yes

Abstract

Cu2SnS3 is a good alternative to solve the problems related to CdTe and CIGS absorber layers having toxic, expensive and rare-earth elements. In this study, CTS films were obtained by a two-stage process that includes sulfurization of Sn-Cu metallic precursors stacked by thermal evaporation. Sulfurization process was carried out in the temperature range of 400-550 degrees C, and the role of the sulfurization temperature on secondary phases of CTS films was reported. XRD and Raman analyzes revealed that CTS film sulfurized at 550 degrees C has a highly crystalline tetragonal-CTS phase, and undesirable CuS secondary phase can be significantly minimized due to increased sulfurization temperature. Elemental analyses showed that desired Cu-poor stoichiometry was reached at 550 degrees C and 550 degrees C. Optical analyzes indicated that optical band gap values approached the optimum value for photovoltaic applications, and 1.39 eV was reached especially for CTS-550 film. Thickness and optical constants of the films were determined using spectroscopic ellipsometry. CuS secondary phase in Cu-rich CTS-400 and CTS-450 films brought metallic behavior to the materials, and electrical resistivity of the Cu-poor CTS-550 film approached the appropriate value for photovoltaic applications. Besides, surface analyzes proved that sulfurization temperature has a strong effect on the surface properties and the film surface became more compact at 550 degrees C. As a result, this study showed that higher sulfurization temperatures (especially 550 degrees C) contribute to the solution of the CuS secondary phase problem, which limits the performance of CTS-based solar cells.