Near 13% efficient semitransparent Cu(In,Ga)S2 solar cells with band gap of 1.6 eV on transparent back contact

Fuente: arXiv
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Main Authors: Kaur, Kulwinder, Oli, Arivazhagan Valluvar, Melchiorre, Michele, Hempel, Wolfram, Witte, Wolfram, Keller, Jan, Siebentritt, Susanne
Format: Preprint
Published: 2026
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author Kaur, Kulwinder
Oli, Arivazhagan Valluvar
Melchiorre, Michele
Hempel, Wolfram
Witte, Wolfram
Keller, Jan
Siebentritt, Susanne
author_facet Kaur, Kulwinder
Oli, Arivazhagan Valluvar
Melchiorre, Michele
Hempel, Wolfram
Witte, Wolfram
Keller, Jan
Siebentritt, Susanne
contents Wide-gap Cu(In,Ga)S2 solar cells with In2O3:Sn (ITO) as transparent back contact are evaluated for the application as top cells in tandem devices. The effect of Na on the solar cell performance is investigated by supplying additional Na by NaF co-evaporation or exclusively by Na diffusion from glass. An efficiency of 12.7% is achieved for a semitransparent solar cell with a band gap of 1.6 eV, with sufficient Na diffusion from glass only, allowed by a thin ITO layer. Absorber grown with additional NaF co-evaporation during Cu(In,Ga)S2 growth on thicker ITO show a comparable efficiency of 12%. High temperature growth at Tsub = 630°C enhances overall absorber quality and results in wide-gap absorbers, with photoluminescence quantum yield improved to 1.5 x 10-5, two orders of magnitude higher than absorber grown at low temperature. NaF co-evaporation is effective in suppressing deep defects, thereby reducing non-radiative recombination and enhancing photoluminescence quantum yield further. A GaOx interfacial layer is formed at the rear contact, likely contributing to the passivation of the back contact. With the presence of thick GaOx layer, current blocking effects are visible in the current-voltage curves. On the contrary, a thinner ITO tends to result in thinner GaOx layer and no current blocking is observed.
format Preprint
id arxiv_https___arxiv_org_abs_2604_05837
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Near 13% efficient semitransparent Cu(In,Ga)S2 solar cells with band gap of 1.6 eV on transparent back contact
Kaur, Kulwinder
Oli, Arivazhagan Valluvar
Melchiorre, Michele
Hempel, Wolfram
Witte, Wolfram
Keller, Jan
Siebentritt, Susanne
Materials Science
Wide-gap Cu(In,Ga)S2 solar cells with In2O3:Sn (ITO) as transparent back contact are evaluated for the application as top cells in tandem devices. The effect of Na on the solar cell performance is investigated by supplying additional Na by NaF co-evaporation or exclusively by Na diffusion from glass. An efficiency of 12.7% is achieved for a semitransparent solar cell with a band gap of 1.6 eV, with sufficient Na diffusion from glass only, allowed by a thin ITO layer. Absorber grown with additional NaF co-evaporation during Cu(In,Ga)S2 growth on thicker ITO show a comparable efficiency of 12%. High temperature growth at Tsub = 630°C enhances overall absorber quality and results in wide-gap absorbers, with photoluminescence quantum yield improved to 1.5 x 10-5, two orders of magnitude higher than absorber grown at low temperature. NaF co-evaporation is effective in suppressing deep defects, thereby reducing non-radiative recombination and enhancing photoluminescence quantum yield further. A GaOx interfacial layer is formed at the rear contact, likely contributing to the passivation of the back contact. With the presence of thick GaOx layer, current blocking effects are visible in the current-voltage curves. On the contrary, a thinner ITO tends to result in thinner GaOx layer and no current blocking is observed.
title Near 13% efficient semitransparent Cu(In,Ga)S2 solar cells with band gap of 1.6 eV on transparent back contact
topic Materials Science
url https://arxiv.org/abs/2604.05837