The effect of the substrate on KF post deposition treatments of narrow gap Cu(In,Ga)Se2 absorber layers

Alkali post deposition treatments (PDT) are the standard method to increase the efficiency of Cu(In,Ga)Se _2 solar cells. In this study, the effects of potassium fluoride (KF) PDTs on narrow band gap Cu(In, Ga)Se _2 (CIS) layers are investigated. The CIS layers were grown on substrates such as glass...

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Main Authors: Jessica de Wild, Guy Brammertz, Tim Oris, Tom Aernouts, Bart Vermang
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:JPhys Energy
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Online Access:https://doi.org/10.1088/2515-7655/adeae6
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author Jessica de Wild
Guy Brammertz
Tim Oris
Tom Aernouts
Bart Vermang
author_facet Jessica de Wild
Guy Brammertz
Tim Oris
Tom Aernouts
Bart Vermang
author_sort Jessica de Wild
collection DOAJ
description Alkali post deposition treatments (PDT) are the standard method to increase the efficiency of Cu(In,Ga)Se _2 solar cells. In this study, the effects of potassium fluoride (KF) PDTs on narrow band gap Cu(In, Ga)Se _2 (CIS) layers are investigated. The CIS layers were grown on substrates such as glass with alkali-barrier/Mo, glass/Mo, and glass/indium-doped tin oxide. It was found that the effect of the PDT depends on the substrates and that there are conditions under which KF-PDT is detrimental to solar cell performance. Time-of-flight secondary ion mass spectrometry measurements revealed limited ion exchange between Na and K, which caused inhibited diffusion of K into the absorber layer. Further opto-electrical characterization indicated increased recombination in the solar cell. Capacitance–voltage–frequency measurements combined with modelling revealed the formation of an interface defect that is limiting the open circuit voltage and reducing the fill factor. Our findings suggest that the lack of K diffusion into the absorber layer promotes the formation of defects at the surface. This study highlights the complex interaction between alkali coming from PDT and the alkali already present in the absorber layer.
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spelling doaj-art-ff7b1c6473834954ba5dcb4651d1a2f42025-08-20T03:23:30ZengIOP PublishingJPhys Energy2515-76552025-01-017404501110.1088/2515-7655/adeae6The effect of the substrate on KF post deposition treatments of narrow gap Cu(In,Ga)Se2 absorber layersJessica de Wild0https://orcid.org/0000-0003-2291-4674Guy Brammertz1https://orcid.org/0000-0003-1404-7339Tim Oris2https://orcid.org/0000-0003-0007-4918Tom Aernouts3https://orcid.org/0000-0002-3004-6080Bart Vermang4https://orcid.org/0000-0003-2669-2087Hasselt University, imo-imomec , Martelarenlaan 42, 3500 Hasselt, Belgium; Imec, imo-imomec , Thor Park 8320, 3600 Genk, Belgium; EnergyVille, imo-imomec , Thor Park 8320, 3600 Genk, BelgiumHasselt University, imo-imomec , Martelarenlaan 42, 3500 Hasselt, Belgium; Imec, imo-imomec , Thor Park 8320, 3600 Genk, Belgium; EnergyVille, imo-imomec , Thor Park 8320, 3600 Genk, BelgiumHasselt University, imo-imomec , Martelarenlaan 42, 3500 Hasselt, Belgium; Imec, imo-imomec , Thor Park 8320, 3600 Genk, Belgium; EnergyVille, imo-imomec , Thor Park 8320, 3600 Genk, BelgiumHasselt University, imo-imomec , Martelarenlaan 42, 3500 Hasselt, Belgium; Imec, imo-imomec , Thor Park 8320, 3600 Genk, Belgium; EnergyVille, imo-imomec , Thor Park 8320, 3600 Genk, BelgiumHasselt University, imo-imomec , Martelarenlaan 42, 3500 Hasselt, Belgium; Imec, imo-imomec , Thor Park 8320, 3600 Genk, Belgium; EnergyVille, imo-imomec , Thor Park 8320, 3600 Genk, BelgiumAlkali post deposition treatments (PDT) are the standard method to increase the efficiency of Cu(In,Ga)Se _2 solar cells. In this study, the effects of potassium fluoride (KF) PDTs on narrow band gap Cu(In, Ga)Se _2 (CIS) layers are investigated. The CIS layers were grown on substrates such as glass with alkali-barrier/Mo, glass/Mo, and glass/indium-doped tin oxide. It was found that the effect of the PDT depends on the substrates and that there are conditions under which KF-PDT is detrimental to solar cell performance. Time-of-flight secondary ion mass spectrometry measurements revealed limited ion exchange between Na and K, which caused inhibited diffusion of K into the absorber layer. Further opto-electrical characterization indicated increased recombination in the solar cell. Capacitance–voltage–frequency measurements combined with modelling revealed the formation of an interface defect that is limiting the open circuit voltage and reducing the fill factor. Our findings suggest that the lack of K diffusion into the absorber layer promotes the formation of defects at the surface. This study highlights the complex interaction between alkali coming from PDT and the alkali already present in the absorber layer.https://doi.org/10.1088/2515-7655/adeae6narrow band gap CIGSalkali treatmentToF-SIMS depth profilesbias dependent admittance spectroscopy
spellingShingle Jessica de Wild
Guy Brammertz
Tim Oris
Tom Aernouts
Bart Vermang
The effect of the substrate on KF post deposition treatments of narrow gap Cu(In,Ga)Se2 absorber layers
JPhys Energy
narrow band gap CIGS
alkali treatment
ToF-SIMS depth profiles
bias dependent admittance spectroscopy
title The effect of the substrate on KF post deposition treatments of narrow gap Cu(In,Ga)Se2 absorber layers
title_full The effect of the substrate on KF post deposition treatments of narrow gap Cu(In,Ga)Se2 absorber layers
title_fullStr The effect of the substrate on KF post deposition treatments of narrow gap Cu(In,Ga)Se2 absorber layers
title_full_unstemmed The effect of the substrate on KF post deposition treatments of narrow gap Cu(In,Ga)Se2 absorber layers
title_short The effect of the substrate on KF post deposition treatments of narrow gap Cu(In,Ga)Se2 absorber layers
title_sort effect of the substrate on kf post deposition treatments of narrow gap cu in ga se2 absorber layers
topic narrow band gap CIGS
alkali treatment
ToF-SIMS depth profiles
bias dependent admittance spectroscopy
url https://doi.org/10.1088/2515-7655/adeae6
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