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Heavy Alkali Treatment of Cu(In,Ga)Se 2 Solar Cells: Surface versus Bulk Effects
- Source :
- Advanced Energy Materials, Advanced Energy Materials, Wiley-VCH Verlag, 2020, pp.1903752. ⟨10.1002/aenm.201903752⟩, Advanced Energy Materials, 2020, pp.1903752. ⟨10.1002/aenm.201903752⟩, Article
- Publication Year :
- 2020
- Publisher :
- HAL CCSD, 2020.
-
Abstract
- Chalcopyrite solar cells achieve efficiencies above 23%. The latest improvements are due to post-deposition treatments (PDT) with heavy alkalis. This study provides a comprehensive description of the effect of PDT on the chemical and electronic structure of surface and bulk of Cu(In,Ga)Se-2. Chemical changes at the surface appear similar, independent of absorber or alkali. However, the effect on the surface electronic structure differs with absorber or type of treatment, although the improvement of the solar cell efficiency is the same. Thus, changes at the surface cannot be the only effect of the PDT treatment. The main effect of PDT with heavy alkalis concerns bulk recombination. The reduction in bulk recombination goes along with a reduced density of electronic tail states. Improvements in open-circuit voltage appear together with reduced band bending at grain boundaries. Heavy alkalis accumulate at grain boundaries and are not detected in the grains. This behavior is understood by the energetics of the formation of single-phase Cu-alkali compounds. Thus, the efficiency improvement with heavy alkali PDT can be attributed to reduced band bending at grain boundaries, which reduces tail states and nonradiative recombination and is caused by accumulation of heavy alkalis at grain boundaries. This work was supported by the European Union's Horizon 2020 research and innovation program under grant agreement no. 641004 (Sharc25) and by the Swiss State Secretariat for Education, Research and Innovation (SERI) under contract number 15.0158. Siebentritt, S (reprint author), Univ Luxembourg, Lab Photovolta, Phys & Mat Sci Res Unit, 41 Rue Brill, L-4422 Belvaux, Luxembourg. susanne.siebentritt@uni.lu
- Subjects :
- 010302 applied physics
Surface (mathematics)
Materials science
Renewable Energy, Sustainability and the Environment
chalcopyrite solar cells
Physics [G04] [Physical, chemical, mathematical & earth Sciences]
grain boundaries
Large scale facilities for research with photons neutrons and ions
02 engineering and technology
021001 nanoscience & nanotechnology
Alkali metal
01 natural sciences
recombination
Physique [G04] [Physique, chimie, mathématiques & sciences de la terre]
Chemical engineering
alkali treatment
0103 physical sciences
[PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci]
surface
General Materials Science
Grain boundary
bulk
0210 nano-technology
Recombination
ComputingMilieux_MISCELLANEOUS
Subjects
Details
- Language :
- English
- ISSN :
- 16146832 and 16146840
- Database :
- OpenAIRE
- Journal :
- Advanced Energy Materials, Advanced Energy Materials, Wiley-VCH Verlag, 2020, pp.1903752. ⟨10.1002/aenm.201903752⟩, Advanced Energy Materials, 2020, pp.1903752. ⟨10.1002/aenm.201903752⟩, Article
- Accession number :
- edsair.doi.dedup.....9cf0c26617c2f6a8105d2377b09345c9