Effect of the burn-out step on the microstructure of the solution-processed Cu(In,Ga)Se2 solar cells

Maria Batuk, Marie Buffiere, Armin E. Zaghi, Nick Lenaers, Christophe Verbist, Samira Khelifi, Jef Vleugels, Marc Meuris, Joke Hadermann

Research output: Contribution to journalArticle

2 Citations (Scopus)


For the development of the photovoltaic industry cheap methods for the synthesis of Cu(In,Ga)Se2 (CIGSe) based solar cells are required. In this work, CIGSe thin films were obtained by a solution-based method using oxygenbearing derivatives. With the aimof improving the morphology of the printed CIGSe layers, we investigated two different annealing conditions of the precursor layer, consisting of (1) a direct selenization step (reference process), and (2) a pre-treatment thermal step prior to the selenization. We showed that the use of an Air/H2S burn-out step prior to the selenization step increases the CIGSe grain size and reduces the carbon content. However, it leads to the reduction of the solar cell efficiency from 4.5% in the reference sample down to 0.5% in the annealed sample. Detailed transmission electron microscopy analysis, including high angle annular dark field scanning transmission electron microscopy and energy dispersive X-ray mapping, was applied to characterize the microstructure of the film and to determine the relationship between microstructure and the solar cell performance. Wedemonstrated that the relatively lowefficiency of the reference solar cells is related not only to the nanosize of the CIGSe grains and presence of the pores in the CIGSe layer, but also to the high amount of secondary phases, namely, In/Ga oxide (or hydroxide)amorphous matter, residuals of organicmatter (carbon), and copper sulfide that is formed at the CIGSe/MoSe2 interface. The annealing inH2S during the burn-out step leads to the formation of the copper sulfide at all grain boundaries and surfaces in the CIGSe layer, which results in the noticeably efficiency drop.

Original languageEnglish
Pages (from-to)142-150
Number of pages9
JournalThin Solid Films
Issue number1
Publication statusPublished - 2015
Externally publishedYes



  • Copper indium gallium selenide
  • Energy dispersive X-ray analysis
  • Non-vacuum process
  • Solar cells
  • Transmission electron microscopy

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Materials Chemistry
  • Metals and Alloys
  • Surfaces, Coatings and Films
  • Surfaces and Interfaces

Cite this

Batuk, M., Buffiere, M., Zaghi, A. E., Lenaers, N., Verbist, C., Khelifi, S., Vleugels, J., Meuris, M., & Hadermann, J. (2015). Effect of the burn-out step on the microstructure of the solution-processed Cu(In,Ga)Se2 solar cells. Thin Solid Films, 583(1), 142-150. https://doi.org/10.1016/j.tsf.2015.03.063