KCN Chemical Etch for Interface Engineering in Cu2ZnSnSe4 Solar Cells

Marie Buffiere, Guy Brammertz, Sylvester Sahayaraj, Maria Batuk, Samira Khelifi, Denis Mangin, Abdel Aziz El Mel, Ludovic Arzel, Joke Hadermann, Marc Meuris, Jef Poortmans

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

The removal of secondary phases from the surface of the kesterite crystals is one of the major challenges to improve the performances of Cu2ZnSn(S,Se)4 (CZTSSe) thin film solar cells. In this contribution, the KCN/KOH chemical etching approach, originally developed for the removal of CuxSe phases in Cu(In,Ga)(S,Se)2 thin films, is applied to CZTSe absorbers exhibiting various chemical compositions. Two distinct electrical behaviors were observed on CZTSe/CdS solar cells after treatment: (i) the improvement of the fill factor (FF) after 30 s of etching for the CZTSe absorbers showing initially a distortion of the electrical characteristic; (ii) the progressive degradation of the FF after long treatment time for all Cu-poor CZTSe solar cell samples. The first effect can be attributed to the action of KCN on the absorber, that is found to clean the absorber free surface from most of the secondary phases surrounding the kesterite grains (e.g., Se0, CuxSe, SnSex, SnO2, Cu2SnSe3 phases, excepting the ZnSe-based phases). The second observation was identified as a consequence of the preferential etching of Se, Sn, and Zn from the CZTSe surface by the KOH solution, combined with the modification of the alkali content of the absorber. The formation of a Cu-rich shell at the absorber/buffer layer interface, leading to the increase of the recombination rate at the interface, and the increase in the doping of the absorber layer after etching are found to be at the origin of the deterioration of the FF of the solar cells.

Original languageEnglish
Pages (from-to)14690-14698
Number of pages9
JournalACS Applied Materials and Interfaces
Volume7
Issue number27
DOIs
Publication statusPublished - 15 Jul 2015

Fingerprint

Etching
Solar cells
Alkalies
Buffer layers
Deterioration
Doping (additives)
Degradation
Thin films
Crystals
Chemical analysis

Keywords

  • CZTSe
  • KCN
  • kesterite
  • photovoltaic
  • selective etching
  • surface

ASJC Scopus subject areas

  • Materials Science(all)

Cite this

Buffiere, M., Brammertz, G., Sahayaraj, S., Batuk, M., Khelifi, S., Mangin, D., ... Poortmans, J. (2015). KCN Chemical Etch for Interface Engineering in Cu2ZnSnSe4 Solar Cells. ACS Applied Materials and Interfaces, 7(27), 14690-14698. https://doi.org/10.1021/acsami.5b02122

KCN Chemical Etch for Interface Engineering in Cu2ZnSnSe4 Solar Cells. / Buffiere, Marie; Brammertz, Guy; Sahayaraj, Sylvester; Batuk, Maria; Khelifi, Samira; Mangin, Denis; El Mel, Abdel Aziz; Arzel, Ludovic; Hadermann, Joke; Meuris, Marc; Poortmans, Jef.

In: ACS Applied Materials and Interfaces, Vol. 7, No. 27, 15.07.2015, p. 14690-14698.

Research output: Contribution to journalArticle

Buffiere, M, Brammertz, G, Sahayaraj, S, Batuk, M, Khelifi, S, Mangin, D, El Mel, AA, Arzel, L, Hadermann, J, Meuris, M & Poortmans, J 2015, 'KCN Chemical Etch for Interface Engineering in Cu2ZnSnSe4 Solar Cells', ACS Applied Materials and Interfaces, vol. 7, no. 27, pp. 14690-14698. https://doi.org/10.1021/acsami.5b02122
Buffiere, Marie ; Brammertz, Guy ; Sahayaraj, Sylvester ; Batuk, Maria ; Khelifi, Samira ; Mangin, Denis ; El Mel, Abdel Aziz ; Arzel, Ludovic ; Hadermann, Joke ; Meuris, Marc ; Poortmans, Jef. / KCN Chemical Etch for Interface Engineering in Cu2ZnSnSe4 Solar Cells. In: ACS Applied Materials and Interfaces. 2015 ; Vol. 7, No. 27. pp. 14690-14698.
@article{ee57b98671b549338469cf9e5f2e6310,
title = "KCN Chemical Etch for Interface Engineering in Cu2ZnSnSe4 Solar Cells",
abstract = "The removal of secondary phases from the surface of the kesterite crystals is one of the major challenges to improve the performances of Cu2ZnSn(S,Se)4 (CZTSSe) thin film solar cells. In this contribution, the KCN/KOH chemical etching approach, originally developed for the removal of CuxSe phases in Cu(In,Ga)(S,Se)2 thin films, is applied to CZTSe absorbers exhibiting various chemical compositions. Two distinct electrical behaviors were observed on CZTSe/CdS solar cells after treatment: (i) the improvement of the fill factor (FF) after 30 s of etching for the CZTSe absorbers showing initially a distortion of the electrical characteristic; (ii) the progressive degradation of the FF after long treatment time for all Cu-poor CZTSe solar cell samples. The first effect can be attributed to the action of KCN on the absorber, that is found to clean the absorber free surface from most of the secondary phases surrounding the kesterite grains (e.g., Se0, CuxSe, SnSex, SnO2, Cu2SnSe3 phases, excepting the ZnSe-based phases). The second observation was identified as a consequence of the preferential etching of Se, Sn, and Zn from the CZTSe surface by the KOH solution, combined with the modification of the alkali content of the absorber. The formation of a Cu-rich shell at the absorber/buffer layer interface, leading to the increase of the recombination rate at the interface, and the increase in the doping of the absorber layer after etching are found to be at the origin of the deterioration of the FF of the solar cells.",
keywords = "CZTSe, KCN, kesterite, photovoltaic, selective etching, surface",
author = "Marie Buffiere and Guy Brammertz and Sylvester Sahayaraj and Maria Batuk and Samira Khelifi and Denis Mangin and {El Mel}, {Abdel Aziz} and Ludovic Arzel and Joke Hadermann and Marc Meuris and Jef Poortmans",
year = "2015",
month = "7",
day = "15",
doi = "10.1021/acsami.5b02122",
language = "English",
volume = "7",
pages = "14690--14698",
journal = "ACS Applied Materials and Interfaces",
issn = "1944-8244",
publisher = "American Chemical Society",
number = "27",

}

TY - JOUR

T1 - KCN Chemical Etch for Interface Engineering in Cu2ZnSnSe4 Solar Cells

AU - Buffiere, Marie

AU - Brammertz, Guy

AU - Sahayaraj, Sylvester

AU - Batuk, Maria

AU - Khelifi, Samira

AU - Mangin, Denis

AU - El Mel, Abdel Aziz

AU - Arzel, Ludovic

AU - Hadermann, Joke

AU - Meuris, Marc

AU - Poortmans, Jef

PY - 2015/7/15

Y1 - 2015/7/15

N2 - The removal of secondary phases from the surface of the kesterite crystals is one of the major challenges to improve the performances of Cu2ZnSn(S,Se)4 (CZTSSe) thin film solar cells. In this contribution, the KCN/KOH chemical etching approach, originally developed for the removal of CuxSe phases in Cu(In,Ga)(S,Se)2 thin films, is applied to CZTSe absorbers exhibiting various chemical compositions. Two distinct electrical behaviors were observed on CZTSe/CdS solar cells after treatment: (i) the improvement of the fill factor (FF) after 30 s of etching for the CZTSe absorbers showing initially a distortion of the electrical characteristic; (ii) the progressive degradation of the FF after long treatment time for all Cu-poor CZTSe solar cell samples. The first effect can be attributed to the action of KCN on the absorber, that is found to clean the absorber free surface from most of the secondary phases surrounding the kesterite grains (e.g., Se0, CuxSe, SnSex, SnO2, Cu2SnSe3 phases, excepting the ZnSe-based phases). The second observation was identified as a consequence of the preferential etching of Se, Sn, and Zn from the CZTSe surface by the KOH solution, combined with the modification of the alkali content of the absorber. The formation of a Cu-rich shell at the absorber/buffer layer interface, leading to the increase of the recombination rate at the interface, and the increase in the doping of the absorber layer after etching are found to be at the origin of the deterioration of the FF of the solar cells.

AB - The removal of secondary phases from the surface of the kesterite crystals is one of the major challenges to improve the performances of Cu2ZnSn(S,Se)4 (CZTSSe) thin film solar cells. In this contribution, the KCN/KOH chemical etching approach, originally developed for the removal of CuxSe phases in Cu(In,Ga)(S,Se)2 thin films, is applied to CZTSe absorbers exhibiting various chemical compositions. Two distinct electrical behaviors were observed on CZTSe/CdS solar cells after treatment: (i) the improvement of the fill factor (FF) after 30 s of etching for the CZTSe absorbers showing initially a distortion of the electrical characteristic; (ii) the progressive degradation of the FF after long treatment time for all Cu-poor CZTSe solar cell samples. The first effect can be attributed to the action of KCN on the absorber, that is found to clean the absorber free surface from most of the secondary phases surrounding the kesterite grains (e.g., Se0, CuxSe, SnSex, SnO2, Cu2SnSe3 phases, excepting the ZnSe-based phases). The second observation was identified as a consequence of the preferential etching of Se, Sn, and Zn from the CZTSe surface by the KOH solution, combined with the modification of the alkali content of the absorber. The formation of a Cu-rich shell at the absorber/buffer layer interface, leading to the increase of the recombination rate at the interface, and the increase in the doping of the absorber layer after etching are found to be at the origin of the deterioration of the FF of the solar cells.

KW - CZTSe

KW - KCN

KW - kesterite

KW - photovoltaic

KW - selective etching

KW - surface

UR - http://www.scopus.com/inward/record.url?scp=84937043953&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84937043953&partnerID=8YFLogxK

U2 - 10.1021/acsami.5b02122

DO - 10.1021/acsami.5b02122

M3 - Article

VL - 7

SP - 14690

EP - 14698

JO - ACS Applied Materials and Interfaces

JF - ACS Applied Materials and Interfaces

SN - 1944-8244

IS - 27

ER -