1. Sulfurization of Co-Evaporated Cu(In,Ga)Se-2 as a Postdeposition Treatment
- Author
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Jonathan J. Scragg, Jan Keller, Charlotte Platzer-Björkman, Jes K. Larsen, Lars Riekehr, Olle Lundberg, and Tobias Jarmar
- Subjects
Materials science ,Band gap ,Annealing (metallurgy) ,Analytical chemistry ,chemistry.chemical_element ,02 engineering and technology ,01 natural sciences ,Temperature measurement ,Teknik och teknologier ,0103 physical sciences ,Ga)Se-2 (CIGSe) ,Surface layer ,Electrical and Electronic Engineering ,Gallium ,postdeposition treatment ,010302 applied physics ,Energy conversion efficiency ,Cu(In ,surface treatment ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Sulfur ,Electronic, Optical and Magnetic Materials ,chemistry ,thin-film solar cells ,Engineering and Technology ,0210 nano-technology ,Den kondenserade materiens fysik ,Selenium ,Alloying - Abstract
It is investigated if the performance of Cu(In,Ga)Se-2 (CIGSe) solar cells produced by co-evaporation can be improved by surface sulfurization in a postdeposition treatment. The expected benefit would be the formation of a sulfur/selenium gradient resulting in reduced interface recombination and increased open-circuit voltage. In the conditions used here it was, however, found that the reaction of the CIGSe layer in a sulfur environment results in the formation of a CuInS2 (CIS) surface phase containing no or very little selenium and gallium. At the same time, a significant pile up of gallium was observed at the CIGSe/CIS boundary. This surface structure was formed for a wide range of annealing conditions investigated in this paper. Increasing the temperature or extending the time of the dwell stage had a similar effect on the material. The gallium enrichment and CIS surface layer widens the surface bandgap and therefore increases the open-circuit voltage. At the same time, the fill factor is reduced, since the interface layer acts as an electron barrier. Due to the balance of these effects, the conversion efficiency could not be improved.
- Published
- 2018