Similarities and Critical Differences in Heavy Alkali-Metal Rubidium and Cesium Effects on Chalcopyrite Cu(In,Ga)Se2 Thin-Film Solar Cells

Shogo Ishizuka; Noboru Taguchi; Paul J. Fons

doi:10.1021/acs.jpcc.9b06042

Similarities and Critical Differences in Heavy Alkali-Metal Rubidium and Cesium Effects on Chalcopyrite Cu(In,Ga)Se₂ Thin-Film Solar Cells

Shogo Ishizuka, Noboru Taguchi, Paul J. Fons

Research output: Contribution to journal › Article › peer-review

29 Citations (Scopus)

Abstract

Both elemental Rb and Cs are known as effective dopants in enhancing Cu(In,Ga)Se₂ (CIGS) thin-film photovoltaic device performance. It is, however, found that there are critical differences in the effects of these two alkali metals on CIGS thin-film properties. Namely, CIGS film surfaces show RbInSe₂ compound formation after RbF postdeposition treatment (PDT), whereas no such segregated compound formation is observed with CsF-PDT. On the other hand, both Rb and Cs have the effect of increasing effective hole carrier density, photoluminescence intensity, and carrier lifetime in CIGS similar to the effects of the lighter alkali-metals Na and K. The fundamental mechanism behind metastable acceptor formation, which is known as the light-soaking or bias-soaking effect leading to CIGS photovoltaic performance enhancement, is experimentally revealed to be independent of the presence of alkali metals in CIGS, and alkali-metals still have an effect of facilitating metastable acceptor formation.

Original language	English
Pages (from-to)	17757-17764
Number of pages	8
Journal	Journal of Physical Chemistry C
Volume	123
Issue number	29
DOIs	https://doi.org/10.1021/acs.jpcc.9b06042
Publication status	Published - 2019 Jul 25
Externally published	Yes

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
Energy(all)
Physical and Theoretical Chemistry
Surfaces, Coatings and Films

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

Access to Document

10.1021/acs.jpcc.9b06042

Cite this

@article{0bfb96c331e941609d63469f8dbbf229,

title = "Similarities and Critical Differences in Heavy Alkali-Metal Rubidium and Cesium Effects on Chalcopyrite Cu(In,Ga)Se2 Thin-Film Solar Cells",

abstract = "Both elemental Rb and Cs are known as effective dopants in enhancing Cu(In,Ga)Se2 (CIGS) thin-film photovoltaic device performance. It is, however, found that there are critical differences in the effects of these two alkali metals on CIGS thin-film properties. Namely, CIGS film surfaces show RbInSe2 compound formation after RbF postdeposition treatment (PDT), whereas no such segregated compound formation is observed with CsF-PDT. On the other hand, both Rb and Cs have the effect of increasing effective hole carrier density, photoluminescence intensity, and carrier lifetime in CIGS similar to the effects of the lighter alkali-metals Na and K. The fundamental mechanism behind metastable acceptor formation, which is known as the light-soaking or bias-soaking effect leading to CIGS photovoltaic performance enhancement, is experimentally revealed to be independent of the presence of alkali metals in CIGS, and alkali-metals still have an effect of facilitating metastable acceptor formation.",

author = "Shogo Ishizuka and Noboru Taguchi and Fons, {Paul J.}",

note = "Funding Information: We thank H. Higuchi, M. Iioka, and H. Takahashi for their help with the experiments and technical support. We also thank Dr. J. Nishinaga, Dr. H. Shibata, and Prof. N. Terada for fruitful discussion. This work was supported by JSPS KAKENHI grant numbers 16K04969 and 19K05282 and also supported in part by NEDO. Publisher Copyright: {\textcopyright} 2019 American Chemical Society.",

year = "2019",

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doi = "10.1021/acs.jpcc.9b06042",

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AU - Ishizuka, Shogo

AU - Taguchi, Noboru

AU - Fons, Paul J.

N1 - Funding Information: We thank H. Higuchi, M. Iioka, and H. Takahashi for their help with the experiments and technical support. We also thank Dr. J. Nishinaga, Dr. H. Shibata, and Prof. N. Terada for fruitful discussion. This work was supported by JSPS KAKENHI grant numbers 16K04969 and 19K05282 and also supported in part by NEDO. Publisher Copyright: © 2019 American Chemical Society.

PY - 2019/7/25

Y1 - 2019/7/25

N2 - Both elemental Rb and Cs are known as effective dopants in enhancing Cu(In,Ga)Se2 (CIGS) thin-film photovoltaic device performance. It is, however, found that there are critical differences in the effects of these two alkali metals on CIGS thin-film properties. Namely, CIGS film surfaces show RbInSe2 compound formation after RbF postdeposition treatment (PDT), whereas no such segregated compound formation is observed with CsF-PDT. On the other hand, both Rb and Cs have the effect of increasing effective hole carrier density, photoluminescence intensity, and carrier lifetime in CIGS similar to the effects of the lighter alkali-metals Na and K. The fundamental mechanism behind metastable acceptor formation, which is known as the light-soaking or bias-soaking effect leading to CIGS photovoltaic performance enhancement, is experimentally revealed to be independent of the presence of alkali metals in CIGS, and alkali-metals still have an effect of facilitating metastable acceptor formation.

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