Abstract
Recent progress in fabricating Cd- and Se-free wide-gap chalcopyrite thin-film solar devices with Zn(S,O) buffer layers prepared by an alternative chemical bath process (CED) using thiourea as complexing agent is discussed. Zn(S,O) has a larger band gap (Eg = 3.6-3.8 eV) than the conventional buffer material CdS (Eg = 2.4eV) currently used in chalcopyrite-based thin films solar cells. Thus, Zn(S,O) is a potential alternative buffer material, which already results in Cd-free solar cell devices with increased spectral response in the blue wavelength region if low-gap chalcopyrites are used. Suitable conditions for reproducible deposition of good-quality Zn(S,O) thin films on wide-gap CuInS2 ('CIS') absorbers have been identified for an alternative, low-temperature chemical route. The thickness of the different Zn(S,O) buffers and the coverage of the CIS absorber by those layers as well as their surface composition were controlled by scanning electron microscopy, X-ray photoelectron spectroscopy, and X-ray excited Auger electron spectroscopy. The minimum thickness required for a complete coverage of the rough CIS absorber by a Zn(S,O) layer deposited by this CBD process was estimated to ∼15 nm. The high transparency of this Zn(S,O) buffer layer in the short-wavelength region leads to an increase of ∼1mA/cm2 in the short-circuit current density of corresponding CIS-based solar cells. Active area efficiencies exceeding 11.0% (total area: 10.4%) have been achieved for the first time, with an open circuit voltage of 700.4mV, a fill factor of 65-8% and a short-circuit current density of 24.5mA/cm2 (total area: 22.5mA/cm2). These results are comparable to the performance of CdS buffered reference cells. First integrated series interconnected mini-modules on 5 Times; 5 cm2 substrates have been prepared and already reach an efficiency (active area: 17.2 cm2) of above 8%.
| Original language | English |
|---|---|
| Pages (from-to) | 499-511 |
| Number of pages | 13 |
| Journal | Progress in Photovoltaics: Research and Applications |
| Volume | 14 |
| Issue number | 6 |
| DOIs | |
| Publication status | Published - Sep 2006 |
| Externally published | Yes |
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Keywords
- Buffer layer
- Cadmium-free
- CuInS
- Efficiency
- Solar cell
- Thin film
- ZnS
ASJC Scopus subject areas
- Energy Engineering and Power Technology
- Fuel Technology
- Physics and Astronomy (miscellaneous)
- Renewable Energy, Sustainability and the Environment
Cite this
Highly-efficient Cd-free CuInS2 thin-film solar cells and mini-modules with Zn(S,O) buffer layers prepared by an alternative chemical bath process. / Ennaoui, A.; Bär, M.; Klaer, J.; Kropp, T.; Sáez-Araoz, R.; Lux-Steiner, M. Ch.
In: Progress in Photovoltaics: Research and Applications, Vol. 14, No. 6, 09.2006, p. 499-511.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Highly-efficient Cd-free CuInS2 thin-film solar cells and mini-modules with Zn(S,O) buffer layers prepared by an alternative chemical bath process
AU - Ennaoui, A.
AU - Bär, M.
AU - Klaer, J.
AU - Kropp, T.
AU - Sáez-Araoz, R.
AU - Lux-Steiner, M. Ch
PY - 2006/9
Y1 - 2006/9
N2 - Recent progress in fabricating Cd- and Se-free wide-gap chalcopyrite thin-film solar devices with Zn(S,O) buffer layers prepared by an alternative chemical bath process (CED) using thiourea as complexing agent is discussed. Zn(S,O) has a larger band gap (Eg = 3.6-3.8 eV) than the conventional buffer material CdS (Eg = 2.4eV) currently used in chalcopyrite-based thin films solar cells. Thus, Zn(S,O) is a potential alternative buffer material, which already results in Cd-free solar cell devices with increased spectral response in the blue wavelength region if low-gap chalcopyrites are used. Suitable conditions for reproducible deposition of good-quality Zn(S,O) thin films on wide-gap CuInS2 ('CIS') absorbers have been identified for an alternative, low-temperature chemical route. The thickness of the different Zn(S,O) buffers and the coverage of the CIS absorber by those layers as well as their surface composition were controlled by scanning electron microscopy, X-ray photoelectron spectroscopy, and X-ray excited Auger electron spectroscopy. The minimum thickness required for a complete coverage of the rough CIS absorber by a Zn(S,O) layer deposited by this CBD process was estimated to ∼15 nm. The high transparency of this Zn(S,O) buffer layer in the short-wavelength region leads to an increase of ∼1mA/cm2 in the short-circuit current density of corresponding CIS-based solar cells. Active area efficiencies exceeding 11.0% (total area: 10.4%) have been achieved for the first time, with an open circuit voltage of 700.4mV, a fill factor of 65-8% and a short-circuit current density of 24.5mA/cm2 (total area: 22.5mA/cm2). These results are comparable to the performance of CdS buffered reference cells. First integrated series interconnected mini-modules on 5 Times; 5 cm2 substrates have been prepared and already reach an efficiency (active area: 17.2 cm2) of above 8%.
AB - Recent progress in fabricating Cd- and Se-free wide-gap chalcopyrite thin-film solar devices with Zn(S,O) buffer layers prepared by an alternative chemical bath process (CED) using thiourea as complexing agent is discussed. Zn(S,O) has a larger band gap (Eg = 3.6-3.8 eV) than the conventional buffer material CdS (Eg = 2.4eV) currently used in chalcopyrite-based thin films solar cells. Thus, Zn(S,O) is a potential alternative buffer material, which already results in Cd-free solar cell devices with increased spectral response in the blue wavelength region if low-gap chalcopyrites are used. Suitable conditions for reproducible deposition of good-quality Zn(S,O) thin films on wide-gap CuInS2 ('CIS') absorbers have been identified for an alternative, low-temperature chemical route. The thickness of the different Zn(S,O) buffers and the coverage of the CIS absorber by those layers as well as their surface composition were controlled by scanning electron microscopy, X-ray photoelectron spectroscopy, and X-ray excited Auger electron spectroscopy. The minimum thickness required for a complete coverage of the rough CIS absorber by a Zn(S,O) layer deposited by this CBD process was estimated to ∼15 nm. The high transparency of this Zn(S,O) buffer layer in the short-wavelength region leads to an increase of ∼1mA/cm2 in the short-circuit current density of corresponding CIS-based solar cells. Active area efficiencies exceeding 11.0% (total area: 10.4%) have been achieved for the first time, with an open circuit voltage of 700.4mV, a fill factor of 65-8% and a short-circuit current density of 24.5mA/cm2 (total area: 22.5mA/cm2). These results are comparable to the performance of CdS buffered reference cells. First integrated series interconnected mini-modules on 5 Times; 5 cm2 substrates have been prepared and already reach an efficiency (active area: 17.2 cm2) of above 8%.
KW - Buffer layer
KW - Cadmium-free
KW - CuInS
KW - Efficiency
KW - Solar cell
KW - Thin film
KW - ZnS
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UR - http://www.scopus.com/inward/citedby.url?scp=33748547207&partnerID=8YFLogxK
U2 - 10.1002/pip.682
DO - 10.1002/pip.682
M3 - Article
VL - 14
SP - 499
EP - 511
JO - Progress in Photovoltaics: Research and Applications
JF - Progress in Photovoltaics: Research and Applications
SN - 1062-7995
IS - 6
ER -