1
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Mina MS, Enkhbayar E, Otgontamir N, Kim S, Kim J. Efficiency Improvement of Narrow Band Gap Cu(In,Ga)(S,Se) 2 Solar Cell with Alkali Treatment via Aqueous Spray Pyrolysis Deposition. ACS APPLIED MATERIALS & INTERFACES 2023; 15:23199-23207. [PMID: 37141630 DOI: 10.1021/acsami.3c02362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The chalcopyrite Cu(In,Ga)(S,Se)2 (CIGSSe) solar cell with a low band gap is a promising candidate for use as the bottom cell in high-efficiency tandem solar cells. In this study, we investigated narrow band gap CIGSSe solar cells, both with and without alkali treatment. The CIGSSe absorbers were fabricated using aqueous spray pyrolysis in an air environment, with the precursor solution prepared by dissolving constituent metal salts. We found that the power conversion efficiency (PCE) of the fabricated solar cell was significantly enhanced when rubidium postdeposition treatment (PDT) was applied to the CIGSSe absorber. The Rb-PDT facilitates defect passivation and a downshift of the valence band maximum of the CIGSSe absorber, thereby improving the power conversion efficiency and all device parameters. Due to these beneficial effects, a PCE of ∼15% was obtained with an energy band gap of less than 1.1 eV, making it suitable for use as the bottom cell in a highly efficient tandem solar cell.
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Affiliation(s)
- Md Salahuddin Mina
- Nano Photoelctronic Device Lab, Department of Physics, Incheon National University, 119 Academy-ro, Yeonsu-gu, Incheon 22012, Republic of Korea
| | - Enkhjargal Enkhbayar
- Nano Photoelctronic Device Lab, Department of Physics, Incheon National University, 119 Academy-ro, Yeonsu-gu, Incheon 22012, Republic of Korea
| | - Namuundari Otgontamir
- Nano Photoelctronic Device Lab, Department of Physics, Incheon National University, 119 Academy-ro, Yeonsu-gu, Incheon 22012, Republic of Korea
| | - SeongYeon Kim
- Division of Energy Technology, Daegu-Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Republic of Korea
| | - JunHo Kim
- Nano Photoelctronic Device Lab, Department of Physics, Incheon National University, 119 Academy-ro, Yeonsu-gu, Incheon 22012, Republic of Korea
- Global Energy Research Center for Carbon Neutrality, Incheon National University, 119 Academy-ro, Yeonsu-gu, Incheon 22012, Republic of Korea
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2
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Elizabeth A, Sahoo SK, Phirke H, Kodalle T, Kühne TD, Audinot JN, Wirtz T, Redinger A, Kaufmann CA, Mirhosseini H, Mönig H. Surface Passivation and Detrimental Heat-Induced Diffusion Effects in RbF-Treated Cu(In,Ga)Se 2 Solar Cell Absorbers. ACS APPLIED MATERIALS & INTERFACES 2022; 14:34101-34112. [PMID: 35848892 DOI: 10.1021/acsami.2c08257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Alkali postdeposition treatments of Cu(In,Ga)Se2 absorbers with KF, RbF, and CsF have led to remarkable efficiency improvements for chalcopyrite thin film solar cells. However, the effect of such treatments on the electronic properties and defect physics of the chalcopyrite absorber surfaces are not yet fully understood. In this work, we use scanning tunneling spectroscopy and X-ray photoelectron spectroscopy to compare the surface defect electronic properties and chemical composition of RbF-treated and nontreated absorbers. We find that the RbF treatment is effective in passivating electronic defect levels at the surface by preventing surface oxidation. Our X-ray photoelectron spectroscopy (XPS) data points to the presence of chemisorbed Rb on the surface with a bonding configuration similar to that of a RbInSe2 bulk compound. Yet, a quantitative analysis indicates Rb coverage in the submonolayer regime, which is likely causing the surface passivation. Furthermore, ab initio calculations confirm that RbF-treated surfaces are less prone to oxidation (in the form of Ga, In, and Se oxides) than bare chalcopyrite surfaces. In addition, elemental diffusion of Rb along with Na, Cu, and Ga is found to occur when the samples are annealed under ultrahigh vacuum conditions. Magnetic sector secondary ion mass spectrometry measurements indicate that there is a homogeneous spatial distribution of Rb on the surface both before and after annealing, albeit with an increased concentration at the surface after heat treatment. Depth-resolved magnetic sector secondary ion mass spectrometry measurements show that Rb diffusion within the bulk occurs predominantly along grain boundaries. Scanning tunneling and XPS measurements after subsequent annealing steps demonstrate that the Rb accumulation at the surface leads to the formation of metallic Rb phases, involving a significant increase of electronic defect levels and/or surface dipole formation. These results strongly suggest a deterioration of the absorber-window interface because of increased recombination losses after the heat-induced diffusion of Rb toward the interface.
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Affiliation(s)
- Amala Elizabeth
- Physikalisches Institut, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Strasse 10, Münster 48149, Germany
- Center for Nanotechnology (CeNTech), Heisenbergstrasse 11, Münster 48149, Germany
| | - Sudhir K Sahoo
- Dynamics of Condensed Matter and Center for Sustainable Systems Design, University of Paderborn, Warburger Strasse 100, Paderborn D-33098, Germany
| | - Himanshu Phirke
- Department of Physics and Materials Science, Université du Luxembourg, 162 A, avenue de la Faïencerie, Luxembourg City L-1511 Luxembourg
| | - Tim Kodalle
- PVcomB/Helmholtz-Zentrum Berlin für Materialien und Energie, Schwarzschildstrasse 3, Berlin 12489, Germany
| | - Thomas D Kühne
- Dynamics of Condensed Matter and Center for Sustainable Systems Design, University of Paderborn, Warburger Strasse 100, Paderborn D-33098, Germany
| | - Jean-Nicolas Audinot
- Advanced Instrumentation for Nano-Analytics (AINA), Materials Research and Technology Department (MRT), Luxembourg Institute of Science and Technology (LIST), Belvaux L-4362, Luxembourg
| | - Tom Wirtz
- Advanced Instrumentation for Nano-Analytics (AINA), Materials Research and Technology Department (MRT), Luxembourg Institute of Science and Technology (LIST), Belvaux L-4362, Luxembourg
| | - Alex Redinger
- Department of Physics and Materials Science, Université du Luxembourg, 162 A, avenue de la Faïencerie, Luxembourg City L-1511 Luxembourg
| | - Christian A Kaufmann
- PVcomB/Helmholtz-Zentrum Berlin für Materialien und Energie, Schwarzschildstrasse 3, Berlin 12489, Germany
| | - Hossein Mirhosseini
- Dynamics of Condensed Matter and Center for Sustainable Systems Design, University of Paderborn, Warburger Strasse 100, Paderborn D-33098, Germany
| | - Harry Mönig
- Physikalisches Institut, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Strasse 10, Münster 48149, Germany
- Center for Nanotechnology (CeNTech), Heisenbergstrasse 11, Münster 48149, Germany
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3
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Nagai T, Nishinaga J, Tampo H, Kim S, Hirayama K, Matsunobe T, Chen G, Ide Y, Ishizuka S, Shibata H, Niki S, Terada N. Impacts of KF Post-Deposition Treatment on the Band Alignment of Epitaxial Cu(In,Ga)Se 2 Heterojunctions. ACS APPLIED MATERIALS & INTERFACES 2022; 14:16780-16790. [PMID: 35380044 DOI: 10.1021/acsami.1c21193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
In this study, we investigated band alignments at CdS/epitaxial CuInxGa1-xSe2 (epi-CIGSe) and epi-CIGSe/GaAs heterointerfaces for solar cell applications using ultraviolet, inverse, and X-ray photoemission spectroscopy (UPS, IPES, and XPS) techniques. We clarified the impacts of KF postdeposition treatment (KF-PDT) at the CdS/epi-CIGSe front heterointerfaces. We found that KF-PDT changed the conduction band alignment at the CdS/epi-CIGSe heterointerface from a cliff to flat configuration, attributed to an increase in the electron affinity (EA) and ionization potential (IP) of the epi-CIGSe surface because of a decrease in Cu and Ga contents. Herein, we discuss the correlation between the impacts of KF-PDT and the solar cell performance. Furthermore, we also investigated the band alignment at the epi-CIGSe/GaAs rear heterointerface. Electron barriers were formed at the epi-CIGSe/GaAs interface, suppressing carrier recombination as the back surface field. Contrarily, a hole accumulation layer is formed by the valence band bending, which is like Ohmic contact.
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Affiliation(s)
- Takehiko Nagai
- Research Institute for Energy Conservation, National Institute of Advanced Industrial Science and Technology (AIST), Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
| | - Jiro Nishinaga
- Research Institute for Energy Conservation, National Institute of Advanced Industrial Science and Technology (AIST), Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
| | - Hitoshi Tampo
- Research Institute for Energy Conservation, National Institute of Advanced Industrial Science and Technology (AIST), Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
| | - Shinho Kim
- Institute of Materials Technology, Pusan National University, Busan 46241, Republic of Korea
| | - Kazuhiro Hirayama
- Graduate School of Science and Engineering, Kagoshima University, 1-21-40 Korimoto, Kagoshima 890-0065, Japan
| | - Tatsuo Matsunobe
- Graduate School of Science and Engineering, Kagoshima University, 1-21-40 Korimoto, Kagoshima 890-0065, Japan
| | - Guanzhong Chen
- Graduate School of Science and Engineering, Kagoshima University, 1-21-40 Korimoto, Kagoshima 890-0065, Japan
| | - Yuya Ide
- Graduate School of Science and Engineering, Kagoshima University, 1-21-40 Korimoto, Kagoshima 890-0065, Japan
| | - Shogo Ishizuka
- Research Institute for Energy Conservation, National Institute of Advanced Industrial Science and Technology (AIST), Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
| | - Hajime Shibata
- Research Institute for Energy Conservation, National Institute of Advanced Industrial Science and Technology (AIST), Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
| | - Shigeru Niki
- Research Institute for Energy Conservation, National Institute of Advanced Industrial Science and Technology (AIST), Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
| | - Norio Terada
- Graduate School of Science and Engineering, Kagoshima University, 1-21-40 Korimoto, Kagoshima 890-0065, Japan
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4
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Martin NM, Törndahl T, Wallin E, Simonov KA, Rensmo H, Platzer-Björkman C. Surface/Interface Effects by Alkali Postdeposition Treatments of (Ag,Cu)(In,Ga)Se 2 Thin Film Solar Cells. ACS APPLIED ENERGY MATERIALS 2022; 5:461-468. [PMID: 35098042 PMCID: PMC8790805 DOI: 10.1021/acsaem.1c02990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 12/06/2021] [Indexed: 06/14/2023]
Abstract
Ag alloying and the introduction of alkali elements through a postdeposition treatment are two approaches to improve the performance of Cu(In,Ga)Se2 (CIGS) thin film solar cells. In particular, a postdeposition treatment of an alkali metal fluoride of the absorber has shown a beneficial effect on the solar cells performance due to an increase in the open circuit voltage (V OC) for both (Ag,Cu)(In,Ga)Se2 (ACIGS) and CIGS based solar cells. Several reasons have been suggested for the improved V OC in CIGS solar cells including absorber surface and interface effects. Less works investigated how the applied postdeposition treatment influences the ACIGS absorber surface and interface properties and the subsequent buffer layer growth. In this work we employed hard X-ray photoelectron spectroscopy to study the chemical and electronic properties at the real functional interface between a CdS buffer and ACIGS absorbers that have been exposed to different alkali metal fluoride treatments during preparation. All samples show an enhanced Ag content at the CdS/ACIGS interface as compared to ACIGS bulk-like composition, and it is also shown that this enhanced Ag content anticorrelates with Ga content. The results indicate that the absorber composition at the near-surface region changes depending on the applied alkali postdeposition treatment. The Cu and Ga decrease and the Ag increase are stronger for the RbF treatment as compared to the CsF treatment, which correlates with the observed device characteristics. This suggests that a selective alkali postdeposition treatment could change the ACIGS absorber surface composition, which can influence the solar cell behavior.
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Affiliation(s)
- Natalia M. Martin
- Solar
Cell Technology, Department of Materials Science and Engineering, Uppsala University, Uppsala, 751 21, Sweden
| | - Tobias Törndahl
- Solar
Cell Technology, Department of Materials Science and Engineering, Uppsala University, Uppsala, 751 21, Sweden
| | - Erik Wallin
- Solibro
Research AB, Vallvägen 5, Uppsala, 756 51, Sweden
| | - Konstantin A. Simonov
- Molecular
and Condensed Matter, Department of Physics and Astronomy, Uppsala University, Uppsala, 751 21, Sweden
| | - Håkan Rensmo
- Molecular
and Condensed Matter, Department of Physics and Astronomy, Uppsala University, Uppsala, 751 21, Sweden
| | - Charlotte Platzer-Björkman
- Solar
Cell Technology, Department of Materials Science and Engineering, Uppsala University, Uppsala, 751 21, Sweden
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5
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Ishizuka S, Nishinaga J, Beppu K, Maeda T, Aoyagi F, Wada T, Yamada A, Chantana J, Nishimura T, Minemoto T, Islam MM, Sakurai T, Terada N. Physical and chemical aspects at the interface and in the bulk of CuInSe 2-based thin-film photovoltaics. Phys Chem Chem Phys 2021; 24:1262-1285. [PMID: 34935800 DOI: 10.1039/d1cp04495h] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Chalcopyrite CuInSe2 (CISe)-based thin-film photovoltaic solar cells have been attracting attention since the 1970s. The technologies of CISe-based thin-film growth and device fabrication processes have already been put into practical applications and today commercial products are available. Nevertheless, there are numerous poorly understood areas in the physical and chemical aspects of the underlying materials science and interfacial and bulk defect physics in CISe-based thin-films and devices for further developments. In this paper, current issues in physical and chemical studies of CISe-based materials and devices are reviewed. Correlations between Cu-deficient phases and the effects of alkali-metals, applications to lightweight and flexible solar minimodules, single-crystalline epitaxial Cu(In,Ga)Se2 films and devices, differences between Cu(In,Ga)Se2 and Ag(In,Ga)Se2 materials, wide-gap CuGaSe2 films and devices, all-dry processed CISe-based solar cells with high photovoltaic efficiencies, and also fundamental studies on open circuit voltage loss analysis and the energy band structure at the interface are among the main areas of discussion in this review.
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Affiliation(s)
- Shogo Ishizuka
- National Institute of Advanced Industrial Science and Technology, Umezono, Tsukuba, Ibaraki, Japan.
| | - Jiro Nishinaga
- National Institute of Advanced Industrial Science and Technology, Umezono, Tsukuba, Ibaraki, Japan.
| | | | | | | | | | - Akira Yamada
- Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo, Japan
| | | | | | | | | | | | - Norio Terada
- Kagoshima University, Korimoto, Kagoshima, Japan
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6
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Lopes TS, de Wild J, Rocha C, Violas A, Cunha JMV, Teixeira JP, Curado MA, Oliveira AJN, Borme J, Birant G, Brammertz G, Fernandes PA, Vermang B, Salomé PMP. On the Importance of Joint Mitigation Strategies for Front, Bulk, and Rear Recombination in Ultrathin Cu(In,Ga)Se 2 Solar Cells. ACS APPLIED MATERIALS & INTERFACES 2021; 13:27713-27725. [PMID: 34086435 DOI: 10.1021/acsami.1c07943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Several optoelectronic issues, such as poor optical absorption and recombination, limit the power conversion efficiency of ultrathin Cu(In,Ga)Se2 (CIGS) solar cells. To mitigate recombination losses, two combined strategies were implemented: a potassium fluoride (KF) post-deposition treatment (PDT) and a rear interface passivation strategy based on an aluminum oxide (Al2O3) point contact structure. The simultaneous implementation of both strategies is reported for the first time on ultrathin CIGS devices. Electrical measurements and 1D simulations demonstrate that in specific conditions, devices with only KF-PDT may outperform rear interface passivation based devices. By combining KF-PDT and rear interface passivation, an enhancement in an open-circuit voltage of 178 mV is reached over devices that have a rear passivation only, and of 85 mV over devices with only a KF-PDT process. Time-Resolved Photoluminescence measurements showed the beneficial effects of combining KF-PDT and the rear interface passivation at decreasing recombination losses in the studied devices, enhancing charge carrier lifetime. X-ray photoelectron spectroscopy measurements indicate the presence of an In and Se-rich layer that we linked to be a KInSe2 layer. Our results suggest that when bulk and front interface recombination values are very high, they dominate, and individual passivation strategies work poorly. Hence, this work shows that for ultrathin devices, passivation mitigation strategies need to be implemented in tandem.
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Affiliation(s)
- Tomás S Lopes
- INL - International Iberian Nanotechnology Laboratory, Avenida Mestre José Veiga, 4715-330 Braga, Portugal
- Imec division IMOMEC (partner in Solliance), Wetenschapspark 1, 3590 Diepenbeek, Belgium
- Institute for Material Research (IMO), Hasselt University (partner in Solliance), Agoralaangebouw H, Diepenbeek 3590, Belgium
- EnergyVille, Thorpark, Poort Genk 8310 & 8320, 3600 Genk, Belgium
| | - Jessica de Wild
- Imec division IMOMEC (partner in Solliance), Wetenschapspark 1, 3590 Diepenbeek, Belgium
- Institute for Material Research (IMO), Hasselt University (partner in Solliance), Agoralaangebouw H, Diepenbeek 3590, Belgium
- EnergyVille, Thorpark, Poort Genk 8310 & 8320, 3600 Genk, Belgium
| | - Célia Rocha
- INL - International Iberian Nanotechnology Laboratory, Avenida Mestre José Veiga, 4715-330 Braga, Portugal
| | - André Violas
- INL - International Iberian Nanotechnology Laboratory, Avenida Mestre José Veiga, 4715-330 Braga, Portugal
| | - José M V Cunha
- INL - International Iberian Nanotechnology Laboratory, Avenida Mestre José Veiga, 4715-330 Braga, Portugal
- i3N, Departamento de Física da Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal
- Departamento de Física, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal
| | - Jennifer P Teixeira
- INL - International Iberian Nanotechnology Laboratory, Avenida Mestre José Veiga, 4715-330 Braga, Portugal
| | - Marco A Curado
- INL - International Iberian Nanotechnology Laboratory, Avenida Mestre José Veiga, 4715-330 Braga, Portugal
- Department of Physics, University of Coimbra, CFisUC, R. Larga, P-3004-516 Coimbra, Portugal
| | - António J N Oliveira
- INL - International Iberian Nanotechnology Laboratory, Avenida Mestre José Veiga, 4715-330 Braga, Portugal
| | - Jérôme Borme
- INL - International Iberian Nanotechnology Laboratory, Avenida Mestre José Veiga, 4715-330 Braga, Portugal
| | - Gizem Birant
- Imec division IMOMEC (partner in Solliance), Wetenschapspark 1, 3590 Diepenbeek, Belgium
- Institute for Material Research (IMO), Hasselt University (partner in Solliance), Agoralaangebouw H, Diepenbeek 3590, Belgium
- EnergyVille, Thorpark, Poort Genk 8310 & 8320, 3600 Genk, Belgium
| | - Guy Brammertz
- Imec division IMOMEC (partner in Solliance), Wetenschapspark 1, 3590 Diepenbeek, Belgium
- Institute for Material Research (IMO), Hasselt University (partner in Solliance), Agoralaangebouw H, Diepenbeek 3590, Belgium
- EnergyVille, Thorpark, Poort Genk 8310 & 8320, 3600 Genk, Belgium
| | - Paulo A Fernandes
- INL - International Iberian Nanotechnology Laboratory, Avenida Mestre José Veiga, 4715-330 Braga, Portugal
- CIETI, Departamento de Física, Instituto Superior de Engenharia do Porto, Instituto Politécnico do Porto, Porto 4200-072, Portugal
| | - Bart Vermang
- Imec division IMOMEC (partner in Solliance), Wetenschapspark 1, 3590 Diepenbeek, Belgium
- Institute for Material Research (IMO), Hasselt University (partner in Solliance), Agoralaangebouw H, Diepenbeek 3590, Belgium
- EnergyVille, Thorpark, Poort Genk 8310 & 8320, 3600 Genk, Belgium
| | - Pedro M P Salomé
- INL - International Iberian Nanotechnology Laboratory, Avenida Mestre José Veiga, 4715-330 Braga, Portugal
- Departamento de Física, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal
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Gao Q, Zhang Y, Ao J, Bi J, Yao L, Guo J, Sun G, Liu W, Liu F, Zhang Y, Li W. New Solution-Processed Surface Treatment to Improve the Photovoltaic Properties of Electrodeposited Cu(In,Ga)Se 2 (CIGSe) Solar Cells. ACS APPLIED MATERIALS & INTERFACES 2021; 13:25451-25460. [PMID: 34009933 DOI: 10.1021/acsami.1c00270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The surface Ga content for a CIGSe absorber was closely related to variation in the open-circuit voltage (VOC), while it was generally low on a CIGSe surface fabricated by two-step selenization. In this work, a solution-processed surface treatment based on spin-coating GaCl3 solution onto a CIGSe surface was applied to increase the Ga content on the surface. XPS, XRD, Raman spectroscopy, and band gap extraction based on the external quantum efficiency response demonstrated that GaCl3 post deposition treatment (GaCl3-PDT) can be used to enhance the Ga content on the surface of a CIGSe absorber. Meanwhile, a solution-processed surface treatment with KSCN (KSCN-PDT) was employed to form a transmission barrier for holes by moving the valence band maximum downward and decreasing the interface recombination between the CdS and CIGSe layers. Admittance spectroscopy results revealed that deep defects were passivated by GaCl3-PDT or KSCN-PDT. By applying the combination of GaCl3-PDT and KSCN-PDT, a champion device was realized that exhibited an efficiency of 13.5% with an improved VOC of 610 mV. Comparing the efficiency of the untreated CIGSe solar cells (11.7%), the CIGSe device efficiency with GaCl3-PDT and KSCN-PDT exhibited 15% enhancement.
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Affiliation(s)
- Qing Gao
- Key Laboratory of Photo-electronic Thin Film Devices and Technology of Tianjin, Engineering Research Center of Thin Film Photo-electronic Technology, Ministry of Education, Institute of Photo-electronic Thin Film Devices and Technology of Nankai University, Tianjin 300350, P.R. China
| | - Yongheng Zhang
- Key Laboratory of Photo-electronic Thin Film Devices and Technology of Tianjin, Engineering Research Center of Thin Film Photo-electronic Technology, Ministry of Education, Institute of Photo-electronic Thin Film Devices and Technology of Nankai University, Tianjin 300350, P.R. China
| | - Jianping Ao
- Key Laboratory of Photo-electronic Thin Film Devices and Technology of Tianjin, Engineering Research Center of Thin Film Photo-electronic Technology, Ministry of Education, Institute of Photo-electronic Thin Film Devices and Technology of Nankai University, Tianjin 300350, P.R. China
| | - Jinlian Bi
- Tianjin Key Laboratory of Film Electronic and Communication Devices School of Electrical and Electronic Engineering, Tianjin University of Technology, Tianjin 300384, China
| | - Liyong Yao
- Tianjin Institute of Power Source, Tianjin 300384, P. R. China
| | - Jiajia Guo
- Key Laboratory of Photo-electronic Thin Film Devices and Technology of Tianjin, Engineering Research Center of Thin Film Photo-electronic Technology, Ministry of Education, Institute of Photo-electronic Thin Film Devices and Technology of Nankai University, Tianjin 300350, P.R. China
| | - Guozhong Sun
- Key Laboratory of Photo-electronic Thin Film Devices and Technology of Tianjin, Engineering Research Center of Thin Film Photo-electronic Technology, Ministry of Education, Institute of Photo-electronic Thin Film Devices and Technology of Nankai University, Tianjin 300350, P.R. China
| | - Wei Liu
- Key Laboratory of Photo-electronic Thin Film Devices and Technology of Tianjin, Engineering Research Center of Thin Film Photo-electronic Technology, Ministry of Education, Institute of Photo-electronic Thin Film Devices and Technology of Nankai University, Tianjin 300350, P.R. China
| | - Fangfang Liu
- Key Laboratory of Photo-electronic Thin Film Devices and Technology of Tianjin, Engineering Research Center of Thin Film Photo-electronic Technology, Ministry of Education, Institute of Photo-electronic Thin Film Devices and Technology of Nankai University, Tianjin 300350, P.R. China
| | - Yi Zhang
- Key Laboratory of Photo-electronic Thin Film Devices and Technology of Tianjin, Engineering Research Center of Thin Film Photo-electronic Technology, Ministry of Education, Institute of Photo-electronic Thin Film Devices and Technology of Nankai University, Tianjin 300350, P.R. China
| | - Wei Li
- Tianjin Key Laboratory of Film Electronic and Communication Devices School of Electrical and Electronic Engineering, Tianjin University of Technology, Tianjin 300384, China
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8
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Rusu M, Kodalle T, Choubrac L, Barreau N, Kaufmann CA, Schlatmann R, Unold T. Electronic Structure of the CdS/Cu(In,Ga)Se 2 Interface of KF- and RbF-Treated Samples by Kelvin Probe and Photoelectron Yield Spectroscopy. ACS APPLIED MATERIALS & INTERFACES 2021; 13:7745-7755. [PMID: 33529003 DOI: 10.1021/acsami.0c20976] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Ambient-pressure Kelvin probe and photoelectron yield spectroscopy methods were employed to investigate the impact of the KF and RbF postdeposition treatments (KF-PDT, RbF-PDT) on the electronic features of Cu(In,Ga)Se2 (CIGSe) thin films and the CdS/CIGSe interface in a CdS thickness series that has been sequentially prepared during the chemical bath deposition (CBD) process depending on the deposition time. We observe distinct features correlated to the CBD-CdS growth stages. In particular, we find that after an initial CBD etching stage, the valence band maximum (VBM) of the CIGSe surface is significantly shifted (by 180-620 mV) toward the Fermi level. However, VBM positions at the surface of the CIGSe are still much below the VBM of the CIGSe bulk. The CIGSe surface band gap is found to depend on the type of postdeposition treatment, showing values between 1.46 and 1.58 eV, characteristic for a copper-poor CIGSe surface composition. At the CdS/CIGSe interface, the lowest VBM discontinuity is observed for the RbF-PDT sample. At this interface, a thin layer with a graded band gap is found. We also find that K and Rb act as compensating acceptors in the CdS layer. Detailed energy band diagrams of the CdS/CIGSe heterostructures are proposed.
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Affiliation(s)
- Marin Rusu
- Struktur und Dynamik von Energiematerialien, Helmholtz-Zentrum Berlin für Materialien und Energie, Lise-Meitner Campus, Hahn-Meitner-Platz 1, 14109 Berlin, Germany
| | - Tim Kodalle
- PVcomB, Helmholtz-Zentrum Berlin für Materialien und Energie, Schwarzschildstr. 3, 12489 Berlin, Germany
| | - Leo Choubrac
- Struktur und Dynamik von Energiematerialien, Helmholtz-Zentrum Berlin für Materialien und Energie, Lise-Meitner Campus, Hahn-Meitner-Platz 1, 14109 Berlin, Germany
| | - Nicolas Barreau
- Université de Nantes, CNRS, Institut des Matériaux Jean Rouxel, IMN, F-44000 Nantes, France
| | - Christian A Kaufmann
- PVcomB, Helmholtz-Zentrum Berlin für Materialien und Energie, Schwarzschildstr. 3, 12489 Berlin, Germany
| | - Rutger Schlatmann
- PVcomB, Helmholtz-Zentrum Berlin für Materialien und Energie, Schwarzschildstr. 3, 12489 Berlin, Germany
| | - Thomas Unold
- Struktur und Dynamik von Energiematerialien, Helmholtz-Zentrum Berlin für Materialien und Energie, Lise-Meitner Campus, Hahn-Meitner-Platz 1, 14109 Berlin, Germany
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9
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Mirhosseini H, Kormath Madam Raghupathy R, Sahoo SK, Wiebeler H, Chugh M, Kühne TD. In silico investigation of Cu(In,Ga)Se 2-based solar cells. Phys Chem Chem Phys 2020; 22:26682-26701. [PMID: 33236749 DOI: 10.1039/d0cp04712k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Photovoltaics is one of the most promising and fastest-growing renewable energy technologies. Although the price-performance ratio of solar cells has improved significantly over recent years, further systematic investigations are needed to achieve higher performance and lower cost for future solar cells. In conjunction with experiments, computer simulations are powerful tools to investigate the thermodynamics and kinetics of solar cells. Over the last few years, we have developed and employed advanced computational techniques to gain a better understanding of solar cells based on copper indium gallium selenide (Cu(In,Ga)Se2). Furthermore, we have utilized state-of-the-art data-driven science and machine learning for the development of photovoltaic materials. In this Perspective, we review our results along with a survey of the field.
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Affiliation(s)
- Hossein Mirhosseini
- Dynamics of Condensed Matter and Center for Sustainable Systems Design, Chair of Theoretical Chemistry, University of Paderborn, Warburger Str. 100, 33098 Paderborn, Germany.
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10
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Kim JH, Kim MK, Gadisa A, Stuard SJ, Nahid MM, Kwon S, Bae S, Kim B, Park GS, Won DH, Lee DK, Kim DW, Shin TJ, Do YR, Kim J, Choi WJ, Ade H, Min BK. Morphological-Electrical Property Relation in Cu(In,Ga)(S,Se) 2 Solar Cells: Significance of Crystal Grain Growth and Band Grading by Potassium Treatment. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2020; 16:e2003865. [PMID: 33150725 DOI: 10.1002/smll.202003865] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 08/27/2020] [Indexed: 06/11/2023]
Abstract
Solution-processed Cu(In,Ga)(S,Se)2 (CIGS) has a great potential for the production of large-area photovoltaic devices at low cost. However, CIGS solar cells processed from solution exhibit relatively lower performance compared to vacuum-processed devices because of a lack of proper composition distribution, which is mainly instigated by the limited Se uptake during chalcogenization. In this work, a unique potassium treatment method is utilized to improve the selenium uptake judiciously, enhancing grain sizes and forming a wider bandgap minimum region. Careful engineering of the bandgap grading structure also results in an enlarged space charge region, which is favorable for electron-hole separation and efficient charge carrier collection. Besides, this device processing approach has led to a linearly increasing electron diffusion length and carrier lifetime with increasing the grain size of the CIGS film, which is a critical achievement for enhancing photocurrent yield. Overall, 15% of power conversion efficiency is achieved in solar cells processed from environmentally benign solutions. This approach offers critical insights for precise device design and processing rules for solution-processed CIGS solar cells.
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Affiliation(s)
- Joo-Hyun Kim
- Clean Energy Research Center, Korea Institute of Science and Technology, 5, Hwarang-ro 14-gil, Seongbuk-gu, Seoul, 02792, Republic of Korea
| | - Min Kyu Kim
- Clean Energy Research Center, Korea Institute of Science and Technology, 5, Hwarang-ro 14-gil, Seongbuk-gu, Seoul, 02792, Republic of Korea
| | - Abay Gadisa
- Department of Physics and Organic and Carbon Electronics Laboratories (ORaCEL), North Carolina State University, 851 Main Campus Dr., Raleigh, NC, 27695, USA
| | - Samuel J Stuard
- Department of Physics and Organic and Carbon Electronics Laboratories (ORaCEL), North Carolina State University, 851 Main Campus Dr., Raleigh, NC, 27695, USA
| | - Masrur Morshed Nahid
- Department of Physics and Organic and Carbon Electronics Laboratories (ORaCEL), North Carolina State University, 851 Main Campus Dr., Raleigh, NC, 27695, USA
| | - Soyeong Kwon
- Department of Physics, Ewha Womans University, 52, Ewhayeodae-gil, Seodaemun-gu, Seoul, 03760, Republic of Korea
| | - Soohyun Bae
- Clean Energy Research Center, Korea Institute of Science and Technology, 5, Hwarang-ro 14-gil, Seongbuk-gu, Seoul, 02792, Republic of Korea
| | - Byoungwoo Kim
- Clean Energy Research Center, Korea Institute of Science and Technology, 5, Hwarang-ro 14-gil, Seongbuk-gu, Seoul, 02792, Republic of Korea
| | - Gi Soon Park
- Clean Energy Research Center, Korea Institute of Science and Technology, 5, Hwarang-ro 14-gil, Seongbuk-gu, Seoul, 02792, Republic of Korea
| | - Da Hye Won
- Clean Energy Research Center, Korea Institute of Science and Technology, 5, Hwarang-ro 14-gil, Seongbuk-gu, Seoul, 02792, Republic of Korea
| | - Dong Ki Lee
- Clean Energy Research Center, Korea Institute of Science and Technology, 5, Hwarang-ro 14-gil, Seongbuk-gu, Seoul, 02792, Republic of Korea
| | - Dong-Wook Kim
- Department of Physics, Ewha Womans University, 52, Ewhayeodae-gil, Seodaemun-gu, Seoul, 03760, Republic of Korea
| | - Tae Joo Shin
- UNIST Central Research Facilities, Ulsan National Institute of Science and Technology, 50, UNIST-gil, Ulsan, 44919, Republic of Korea
| | - Young Rag Do
- Department of Chemistry, Kookmin University, 77, Jeongneung-ro, Seongbuk-gu, Seoul, 02707, Republic of Korea
| | - Jihyun Kim
- Department of Chemical and Biological Engineering, Korea University, 145, Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea
| | - Won Jun Choi
- Clean Energy Research Center, Korea Institute of Science and Technology, 5, Hwarang-ro 14-gil, Seongbuk-gu, Seoul, 02792, Republic of Korea
| | - Harald Ade
- Department of Physics and Organic and Carbon Electronics Laboratories (ORaCEL), North Carolina State University, 851 Main Campus Dr., Raleigh, NC, 27695, USA
| | - Byoung Koun Min
- Clean Energy Research Center, Korea Institute of Science and Technology, 5, Hwarang-ro 14-gil, Seongbuk-gu, Seoul, 02792, Republic of Korea
- Graduate School of Energy and Environment, Korea University, 145, Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea
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11
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Harel S, Arzel L, Lepetit T, Zabierowski P, Barreau N. Influence of Sulfur Evaporation during or after KF-Post Deposition Treatment On Cu(In,Ga)Se 2/CdS Interface Formation. ACS APPLIED MATERIALS & INTERFACES 2020; 12:46953-46962. [PMID: 32937069 DOI: 10.1021/acsami.0c12455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
This work investigates the impact of the elemental sulfur evaporation during or after KF-post deposition treatment (KF-PDT) on the resulting Cu(In,Ga)Se2/chemical bath deposited(CBD)-CdS interface. Chemical composition of the various interfaces were determined through Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and X-ray induced Auger spectroscopy (XAES). Cu(In,Ga)Se2 absorber which experienced KF-PDT in selenium atmosphere (KSe sample) exhibits the formation of the well-reported In-Se based topping layer. Additional exposure to elemental sulfur, resulting in KSe+S sample, induces the partial sulfurization of this overlayer and/or of the absorber. After short immersion into the CdS bath, the resulting In-rich surfaces of KSe and KSe+S are likely to turn into few atomic layers of Cd-In-(Se/S)-O whose [S]/[Se]+[S] ratio and O content depend on their respective post deposition treatment. In contrast, KF-PDT performed in S atmosphere does not show an In-rich surface, making the early stage of CdS growth similar to that observed on untreated CIGSe.
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Affiliation(s)
- Sylvie Harel
- CNRS, Institut des Matériaux Jean Rouxel, IMN, Université de Nantes, F-44000 Nantes, France
| | - Ludovic Arzel
- CNRS, Institut des Matériaux Jean Rouxel, IMN, Université de Nantes, F-44000 Nantes, France
| | - Thomas Lepetit
- CNRS, Institut des Matériaux Jean Rouxel, IMN, Université de Nantes, F-44000 Nantes, France
| | - Pawel Zabierowski
- Faculty of Physics, Warsaw University of Technology, Koszykowa 75, 00-662 Warszawa, Poland
| | - Nicolas Barreau
- CNRS, Institut des Matériaux Jean Rouxel, IMN, Université de Nantes, F-44000 Nantes, France
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12
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Bombsch J, Avancini E, Carron R, Handick E, Garcia-Diez R, Hartmann C, Félix R, Ueda S, Wilks RG, Bär M. NaF/RbF-Treated Cu(In,Ga)Se 2 Thin-Film Solar Cell Absorbers: Distinct Surface Modifications Caused by Two Different Types of Rubidium Chemistry. ACS APPLIED MATERIALS & INTERFACES 2020; 12:34941-34948. [PMID: 32633119 DOI: 10.1021/acsami.0c08794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The underlying beneficial mechanism of heavy alkali postdeposition treatment (PDT) of Cu(In,Ga)Se2 thin-film solar cell absorbers that led to new record efficiencies in recent years is studied using photoelectron spectroscopy. Excitation energies between 40.8 eV and 6 keV were used to examine the near-surface region of Cu(In,Ga)Se2 thin-film solar cell absorbers that underwent NaF and combined NaF/RbF PDT. The already Cu-deficient surface region after NaF PDT, which is modeled as a Cu:(In + Ga):Se = 1:5:8 phase, shows further depletion after NaF/RbF PDT and seems to incorporate some Rb. Additionally, we have found strong indications for the NaF/RbF PDT-induced formation of a Rb-In-Se-type compound with a 1:1:2 stoichiometry partially covering the absorber surface. The electronic Cu(In,Ga)Se2 structure is modified due to the RbF treatment, with a pronounced shift in the valence band maximum away from the Fermi level in the immediate vicinity of the surface.
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Affiliation(s)
- Jakob Bombsch
- Interface Design, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Berlin 14109, Germany
| | - Enrico Avancini
- Laboratory for Thin Films and Photovoltaics, Empa-Swiss Federal Laboratories for Materials Science and Technology, Dübendorf 8600, Switzerland
- Now at Faculty of Science and Technology, Free University of Bozen-Bolzano, Bolzano 39100, Italy
| | - Romain Carron
- Laboratory for Thin Films and Photovoltaics, Empa-Swiss Federal Laboratories for Materials Science and Technology, Dübendorf 8600, Switzerland
| | - Evelyn Handick
- Interface Design, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Berlin 14109, Germany
| | - Raul Garcia-Diez
- Interface Design, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Berlin 14109, Germany
| | - Claudia Hartmann
- Interface Design, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Berlin 14109, Germany
| | - Roberto Félix
- Interface Design, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Berlin 14109, Germany
| | - Shigenori Ueda
- NIMS Synchrotron X-ray Station at SPring-8, National Institute for Materials Science (NIMS), 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
- Research Center for Advanced Measurement and Characterization, NIMS, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan
| | - Regan G Wilks
- Interface Design, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Berlin 14109, Germany
- Energy Materials In-Situ Laboratory Berlin (EMIL), Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Berlin 12489, Germany
| | - Marcus Bär
- Interface Design, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Berlin 14109, Germany
- Energy Materials In-Situ Laboratory Berlin (EMIL), Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Berlin 12489, Germany
- Helmholtz-Institute Erlangen-Nürnberg for Renewable Energy (HI ERN), Berlin 91058, Germany
- Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen 12489, Germany
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13
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Yang P, Wilks RG, Yang W, Bär M. Interface Formation between CdS and Alkali Postdeposition-Treated Cu(In,Ga)Se 2 Thin-Film Solar Cell Absorbers-Key To Understanding the Efficiency Gain. ACS APPLIED MATERIALS & INTERFACES 2020; 12:6688-6698. [PMID: 31912731 DOI: 10.1021/acsami.9b20327] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
A combination of X-ray photoelectron/Auger electron spectroscopy and soft X-ray emission spectroscopy has been employed to investigate the impact of different alkali postdeposition treatments (PDTs) on the chemical structure of the (buried) CdS/Cu(In,Ga)Se2 heterojunction: the key interface in chalcopyrite-based thin-film solar cells. Chemical bath deposited (CBD) CdS layers of different thicknesses on NaF PDT (CIGSeNaF) and NaF + KF PDT (CIGSeNaF+KF) Cu(In,Ga)Se2 absorbers prepared at low temperature (to facilitate the use of flexible, e.g., polyimide, substrates) were studied. While we find the CdS/CIGSeNaF interface to be mainly free of significant chemical interaction, in the proximity of the CdS/CIGSeNaF+KF interface, an elemental redistribution involving Cd, In, K, S, and Se is revealed. For the early stages of the CBD-CdS process, our findings are in agreement with the conversion of the K-In-Se-type layer present on the CIGSeNaF+KF surface into a mixed Cd-In-(O,OH,S,Se)-type layer, probably having some Cd-In and (S,O)-Se composition gradients. For long CBD times-independent of employed PDT-we find the buffer material to be best described by a Cd(O,OH,S)-like species rather than by a pure CdS buffer. These findings shed light on the observed performance leap of corresponding CdS/CIGSeNaF+KF-based solar cells.
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Affiliation(s)
- Penghui Yang
- Department Interface Design & Energy Materials In-Situ Laboratory Berlin (EMIL) , Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , 12489 Berlin , Germany
| | - Regan G Wilks
- Department Interface Design & Energy Materials In-Situ Laboratory Berlin (EMIL) , Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , 12489 Berlin , Germany
- Energy Materials In-Situ Laboratory Berlin (EMIL) , Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , 12489 Berlin , Germany
| | - Wanli Yang
- Advanced Light Source Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Marcus Bär
- Department Interface Design & Energy Materials In-Situ Laboratory Berlin (EMIL) , Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , 12489 Berlin , Germany
- Energy Materials In-Situ Laboratory Berlin (EMIL) , Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , 12489 Berlin , Germany
- Department of Chemistry and Pharmacy , Friedrich-Alexander-Universität Erlangen-Nürnberg , Egerlandstr. 3 , 91058 Erlangen , Germany
- Helmholtz Institute Erlangen-Nürnberg für Renewable Energy (HI ERN) , Albert-Einstein-Str. 15 , 12489 Berlin , Germany
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14
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Nicoara N, Manaligod R, Jackson P, Hariskos D, Witte W, Sozzi G, Menozzi R, Sadewasser S. Direct evidence for grain boundary passivation in Cu(In,Ga)Se 2 solar cells through alkali-fluoride post-deposition treatments. Nat Commun 2019; 10:3980. [PMID: 31484943 PMCID: PMC6726603 DOI: 10.1038/s41467-019-11996-y] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 08/16/2019] [Indexed: 11/12/2022] Open
Abstract
The properties and performance of polycrystalline materials depend critically on the properties of their grain boundaries. Polycrystalline photovoltaic materials – e.g. hybrid halide perovskites, copper indium gallium diselenide (CIGSe) and cadmium telluride – have already demonstrated high efficiencies and promise cost-effective electricity supply. For CIGSe-based solar cells, an efficiency above 23% has recently been achieved using an alkali-fluoride post-deposition treatment; however, its full impact and functional principle are not yet fully understood. Here, we show direct evidence for the passivation of grain boundaries in CIGSe treated with three different alkali-fluorides through a detailed study of the nanoscale optoelectronic properties. We determine a correlation of the surface potential change at grain boundaries with the open-circuit voltage, which is supported by numerical simulations. Our results suggest that heavier alkali elements might lead to better passivation by reducing the density of charged defects and increasing the formation of secondary phases at grain boundaries. Grain boundaries play critical roles in determining the properties and performance of solar cells based on polycrystalline materials. Here Nicoara et al. showcase that proper treatments passivate defects at grain boundaries by forming secondary material phases with the CIGSe absorbers and lead to higher Voc.
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Affiliation(s)
- Nicoleta Nicoara
- International Iberian Nanotechnology Laboratory (INL), Av. Mestre José Veiga s/n, 4715-330, Braga, Portugal
| | - Roby Manaligod
- International Iberian Nanotechnology Laboratory (INL), Av. Mestre José Veiga s/n, 4715-330, Braga, Portugal
| | - Philip Jackson
- Zentrum für Sonnenenergie- und Wasserstoff-Forschung Baden-Württemberg (ZSW), Meitnerstr. 1, 70563, Stuttgart, Germany
| | - Dimitrios Hariskos
- Zentrum für Sonnenenergie- und Wasserstoff-Forschung Baden-Württemberg (ZSW), Meitnerstr. 1, 70563, Stuttgart, Germany
| | - Wolfram Witte
- Zentrum für Sonnenenergie- und Wasserstoff-Forschung Baden-Württemberg (ZSW), Meitnerstr. 1, 70563, Stuttgart, Germany
| | - Giovanna Sozzi
- Department of Engineering and Architecture, University of Parma, Parco Area delle Scienze 181A, 43124, Parma, Italy
| | - Roberto Menozzi
- Department of Engineering and Architecture, University of Parma, Parco Area delle Scienze 181A, 43124, Parma, Italy
| | - Sascha Sadewasser
- International Iberian Nanotechnology Laboratory (INL), Av. Mestre José Veiga s/n, 4715-330, Braga, Portugal.
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15
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Chugh M, Kühne TD, Mirhosseini H. Diffusion of Alkali Metals in Polycrystalline CuInSe 2 and Their Role in the Passivation of Grain Boundaries. ACS APPLIED MATERIALS & INTERFACES 2019; 11:14821-14829. [PMID: 30924332 DOI: 10.1021/acsami.9b02158] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The behavior of alkali atom point defects in polycrystalline CuInSe2 is studied. In this work, three grain boundary models, one coherent twin boundary and two twin boundaries with dislocation cores, are considered. Total energy calculations show that all alkali metals tend to segregate at the grain boundaries. In addition, the segregation of alkali atoms is more pronounced at the grain boundaries with the dislocation cores. The diffusion of alkali metals along and near grain boundaries is studied as well. The results show that the diffusion of alkali atoms in the grain boundary models is faster than within the bulk. In addition, the ion exchange between Na and Rb atoms at the grain boundaries leads to the Rb enrichment at the grain boundaries and the increase of the Na concentration in the bulk. While the effects of Na and Rb point defects on the electronic structure of the grain boundary with the anion-core dislocation are similar, Rb atoms passivate the grain boundary with the cation-core dislocation more effectively than Na. This can explain the further improvement of the solar cell performance after the RbF-postdeposition treatment.
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Affiliation(s)
- Manjusha Chugh
- Dynamics of Condensed Matter and Center for Sustainable Systems Design, Chair of Theoretical Chemistry , University of Paderborn , Warburger Str. 100 , D-33098 Paderborn , Germany
| | - Thomas D Kühne
- Dynamics of Condensed Matter and Center for Sustainable Systems Design, Chair of Theoretical Chemistry , University of Paderborn , Warburger Str. 100 , D-33098 Paderborn , Germany
| | - Hossein Mirhosseini
- Dynamics of Condensed Matter and Center for Sustainable Systems Design, Chair of Theoretical Chemistry , University of Paderborn , Warburger Str. 100 , D-33098 Paderborn , Germany
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16
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Kormath Madam Raghupathy R, Kühne TD, Henkelman G, Mirhosseini H. Alkali Atoms Diffusion Mechanism in CuInSe
2
Explained by Kinetic Monte Carlo Simulations. ADVANCED THEORY AND SIMULATIONS 2019. [DOI: 10.1002/adts.201900036] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Ramya Kormath Madam Raghupathy
- Dynamics of Condensed Matter and Center for Sustainable Systems DesignChair of Theoretical ChemistryUniversity of PaderbornWarburger Str. 100 D–33098 Paderborn Germany
| | - Thomas D. Kühne
- Dynamics of Condensed Matter and Center for Sustainable Systems DesignChair of Theoretical ChemistryUniversity of PaderbornWarburger Str. 100 D–33098 Paderborn Germany
| | - Graeme Henkelman
- Department of Chemistry and the Institute for Computational Engineering and SciencesThe University of Texas at AustinAustin TX 78712‐0165 USA
| | - Hossein Mirhosseini
- Dynamics of Condensed Matter and Center for Sustainable Systems DesignChair of Theoretical ChemistryUniversity of PaderbornWarburger Str. 100 D–33098 Paderborn Germany
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17
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Weiss TP, Carron R, Wolter MH, Löckinger J, Avancini E, Siebentritt S, Buecheler S, Tiwari AN. Time-resolved photoluminescence on double graded Cu(In,Ga)Se 2 - Impact of front surface recombination and its temperature dependence. SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 2019; 20:313-323. [PMID: 31044022 PMCID: PMC6484473 DOI: 10.1080/14686996.2019.1586583] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 02/21/2019] [Accepted: 02/21/2019] [Indexed: 06/09/2023]
Abstract
Time-resolved photoluminescence (TRPL) is applied to determine an effective lifetime of minority charge carriers in semiconductors. Such effective lifetimes include recombination channels in the bulk as well as at the surfaces and interfaces of the device. In the case of Cu(In,Ga)Se2 absorbers used for solar cell applications, trapping of minority carriers has also been reported to impact the effective minority carrier lifetime. Trapping can be indicated by an increased temperature dependence of the experimentally determined photoluminescence decay time when compared to the temperature dependence of Shockley-Read-Hall (SRH) recombination alone and can lead to an overestimation of the minority carrier lifetime. Here, it is shown by technology computer-aided design (TCAD) simulations and by experiment that the intentional double-graded bandgap profile of high efficiency Cu(In,Ga)Se2 absorbers causes a temperature dependence of the PL decay time similar to trapping in case of a recombinative front surface. It is demonstrated that a passivated front surface results in a temperature dependence of the decay time that can be explained without minority carrier trapping and thus enables the assessment of the absorber quality by means of the minority carrier lifetime. Comparison with the absolute PL yield and the quasi-Fermi-level splitting (QFLS) corroborate the conclusion that the measured decay time corresponds to the bulk minority carrier lifetime of 250 ns for the double-graded CIGS absorber under investigation.
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Affiliation(s)
- Thomas Paul Weiss
- Laboratory for Thin Films and Photovoltaics, Empa – Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland
- Laboratory for Photovoltaics, Physics and Materials Science Research Unit, University of Luxembourg, Belvaux, Luxembourg
| | - Romain Carron
- Laboratory for Thin Films and Photovoltaics, Empa – Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland
| | - Max H. Wolter
- Laboratory for Photovoltaics, Physics and Materials Science Research Unit, University of Luxembourg, Belvaux, Luxembourg
| | - Johannes Löckinger
- Laboratory for Thin Films and Photovoltaics, Empa – Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland
| | - Enrico Avancini
- Laboratory for Thin Films and Photovoltaics, Empa – Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland
| | - Susanne Siebentritt
- Laboratory for Photovoltaics, Physics and Materials Science Research Unit, University of Luxembourg, Belvaux, Luxembourg
| | - Stephan Buecheler
- Laboratory for Thin Films and Photovoltaics, Empa – Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland
| | - Ayodhya N. Tiwari
- Laboratory for Thin Films and Photovoltaics, Empa – Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland
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18
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Malitckaya M, Kunze T, Komsa HP, Havu V, Handick E, Wilks RG, Bär M, Puska MJ. Alkali Postdeposition Treatment-Induced Changes of the Chemical and Electronic Structure of Cu(In,Ga)Se 2 Thin-Film Solar Cell Absorbers: A First-Principle Perspective. ACS APPLIED MATERIALS & INTERFACES 2019; 11:3024-3033. [PMID: 30592197 PMCID: PMC6727185 DOI: 10.1021/acsami.8b18216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Accepted: 12/28/2018] [Indexed: 06/09/2023]
Abstract
The effects of alkali postdeposition treatment (PDT) on the valence band structure of Cu(In,Ga)Se2 (CIGSe) thin-film solar cell absorbers are addressed from a first-principles perspective. In detail, experimentally derived hard X-ray photoelectron spectroscopy (HAXPES) data [ Handick , E. ; ACS Appl. Mater. Interfaces 2015 , 7 , 27414 - 27420 ] of the valence band structure of alkali-free and NaF/KF-PDT CIGSe are directly compared and fit by calculated density of states (DOS) of CuInSe2, its Cu-deficient counterpart CuIn5Se8, and different potentially formed secondary phases, such as KInSe2, InSe, and In2Se3. The DOSs are based on first-principles electronic structure calculations and weighted according to element-, symmetry-, and energy-dependent photoionization cross sections for the comparison to experimental data. The HAXPES spectra were recorded using photon energies ranging from 2 to 8 keV, allowing extraction of information from different sample depths. The analysis of the alkali-free CIGSe valence band structure reveals that it can best be described by a mixture of the DOS of CuInSe2 and CuIn5Se8, resulting in a stoichiometry slightly more Cu-rich than that of CuIn3Se5. The NaF/KF-PDT-induced changes in the HAXPES spectra for different alkali exposures are best reproduced by additional contributions from KInSe2, with some indications that the formation of a pronounced K-In-Se-type surface species might crucially depend on the amount of K available during PDT.
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Affiliation(s)
- Maria Malitckaya
- Department of Applied
Physics, Aalto University, P.O. Box 11000, 00076 Aalto, Finland
| | - Thomas Kunze
- Department
of Interface Design and Energy Materials In-Situ Laboratory Berlin (EMIL), Helmholtz-Zentrum Berlin für Materialien und
Energie GmbH (HZB), 12489 Berlin, Germany
| | - Hannu-Pekka Komsa
- Department of Applied
Physics, Aalto University, P.O. Box 11000, 00076 Aalto, Finland
| | - Ville Havu
- Department of Applied
Physics, Aalto University, P.O. Box 11000, 00076 Aalto, Finland
| | - Evelyn Handick
- Department
of Interface Design and Energy Materials In-Situ Laboratory Berlin (EMIL), Helmholtz-Zentrum Berlin für Materialien und
Energie GmbH (HZB), 12489 Berlin, Germany
| | - Regan G. Wilks
- Department
of Interface Design and Energy Materials In-Situ Laboratory Berlin (EMIL), Helmholtz-Zentrum Berlin für Materialien und
Energie GmbH (HZB), 12489 Berlin, Germany
| | - Marcus Bär
- Department
of Interface Design and Energy Materials In-Situ Laboratory Berlin (EMIL), Helmholtz-Zentrum Berlin für Materialien und
Energie GmbH (HZB), 12489 Berlin, Germany
- Helmholtz-Institute Erlangen-Nürnberg for Renewable Energy
(HIERN), Forschungszentrum Jülich, 90429 Erlangen, Germany
- Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Martti J. Puska
- Department of Applied
Physics, Aalto University, P.O. Box 11000, 00076 Aalto, Finland
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Schöppe P, Schönherr S, Jackson P, Wuerz R, Wisniewski W, Ritzer M, Zapf M, Johannes A, Schnohr CS, Ronning C. Overall Distribution of Rubidium in Highly Efficient Cu(In,Ga)Se 2 Solar Cells. ACS APPLIED MATERIALS & INTERFACES 2018; 10:40592-40598. [PMID: 30383349 DOI: 10.1021/acsami.8b16040] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Thin-film solar cells based on Cu(In,Ga)Se2 (CIGS) absorbers have achieved conversion efficiencies close to 23%. Such a high performance could be reached by incorporating heavy alkali elements into the CIGS absorber using an alkali fluoride post-deposition treatment (PDT). In order to improve the understanding of the effect of the PDT, we investigated a highly efficient CIGS solar cell whose absorber was subjected to a RbF-PDT. By applying synchrotron-based X-ray fluorescence analysis in combination with scanning transmission electron microscopy and electron backscatter diffraction to a cross-sectional lamella of the whole device, we were able to correlate the local composition of the absorber with its microstructure. The incorporated Rb accumulates at grain boundaries, with a random misorientation of the adjacent grains, at the p-n junction, and at the interface between the absorber and the MoSe2 layer. The accumulation of Rb at the grain boundaries is accompanied by a reduced Cu concentration and slightly increased In and Se concentrations. Additionally, variations in the local composition of the absorber at the p-n junction indicate the formation of a secondary phase, which exhibits a laterally inhomogeneous distribution. The improved solar cell performance due to RbF-PDT can thus be expected to originate from a favorable modification of the back contact interface, the random grain boundaries, the p-n junction, or a combination of these effects.
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Affiliation(s)
- Philipp Schöppe
- Institut für Festkörperphysik , Friedrich-Schiller-Universität Jena , Max-Wien-Platz 1 , 07743 Jena , Germany
| | - Sven Schönherr
- Institut für Festkörperphysik , Friedrich-Schiller-Universität Jena , Max-Wien-Platz 1 , 07743 Jena , Germany
| | - Philip Jackson
- Zentrum für Sonnenenergie und Wasserstoff-Forschung Baden-Württemberg , Meitnerstrasse 1 , 70563 Stuttgart , Germany
| | - Roland Wuerz
- Zentrum für Sonnenenergie und Wasserstoff-Forschung Baden-Württemberg , Meitnerstrasse 1 , 70563 Stuttgart , Germany
| | - Wolfgang Wisniewski
- Otto-Schott-Institut , Friedrich-Schiller-Universität Jena , Fraunhoferstr. 6 , 07743 Jena , Germany
| | - Maurizio Ritzer
- Institut für Festkörperphysik , Friedrich-Schiller-Universität Jena , Max-Wien-Platz 1 , 07743 Jena , Germany
| | - Maximilian Zapf
- Institut für Festkörperphysik , Friedrich-Schiller-Universität Jena , Max-Wien-Platz 1 , 07743 Jena , Germany
| | - Andreas Johannes
- European Synchrotron Radiation Facility (ESRF) , 38043 Grenoble , France
| | - Claudia S Schnohr
- Institut für Festkörperphysik , Friedrich-Schiller-Universität Jena , Max-Wien-Platz 1 , 07743 Jena , Germany
| | - Carsten Ronning
- Institut für Festkörperphysik , Friedrich-Schiller-Universität Jena , Max-Wien-Platz 1 , 07743 Jena , Germany
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20
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Nicoara N, Kunze T, Jackson P, Hariskos D, Duarte RF, Wilks RG, Witte W, Bär M, Sadewasser S. Evidence for Chemical and Electronic Nonuniformities in the Formation of the Interface of RbF-Treated Cu(In,Ga)Se 2 with CdS. ACS APPLIED MATERIALS & INTERFACES 2017; 9:44173-44180. [PMID: 29178776 DOI: 10.1021/acsami.7b12448] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report on the initial stages of CdS buffer layer formation on Cu(In,Ga)Se2 (CIGSe) thin-film solar cell absorbers subjected to rubidium fluoride (RbF) postdeposition treatment (PDT). A detailed characterization of the CIGSe/CdS interface for different chemical bath deposition (CBD) times of the CdS layer is obtained from spatially resolved atomic and Kelvin probe force microscopy and laterally integrating X-ray spectroscopies. The observed spatial inhomogeneity in the interface's structural, chemical, and electronic properties of samples undergoing up to 3 min of CBD treatments is indicative of a complex interface formation including an incomplete coverage and/or nonuniform composition of the buffer layer. It is expected that this result impacts solar cell performance, in particular when reducing the CdS layer thickness (e.g., in an attempt to increase the collection in the ultraviolet wavelength region). Our work provides important findings on the absorber/buffer interface formation and reveals the underlying mechanism for limitations in the reduction of the CdS thickness, even when an alkali PDT is applied to the CIGSe absorber.
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Affiliation(s)
- Nicoleta Nicoara
- International Iberian Nanotechnology Laboratory (INL) , 4715-330 Braga, Portugal
| | - Thomas Kunze
- Renewable Energy, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB) , 14109 Berlin, Germany
| | - Philip Jackson
- Zentrum für Sonnenenergie-und Wasserstoff-Forschung Baden-Württemberg (ZSW) , 70563 Stuttgart, Germany
| | - Dimitrios Hariskos
- Zentrum für Sonnenenergie-und Wasserstoff-Forschung Baden-Württemberg (ZSW) , 70563 Stuttgart, Germany
| | - Roberto Félix Duarte
- Renewable Energy, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB) , 14109 Berlin, Germany
| | - Regan G Wilks
- Renewable Energy, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB) , 14109 Berlin, Germany
- Energy Materials In-Situ Laboratory Berlin (EMIL), Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , 12489 Berlin, Germany
| | - Wolfram Witte
- Zentrum für Sonnenenergie-und Wasserstoff-Forschung Baden-Württemberg (ZSW) , 70563 Stuttgart, Germany
| | - Marcus Bär
- Renewable Energy, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB) , 14109 Berlin, Germany
- Energy Materials In-Situ Laboratory Berlin (EMIL), Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , 12489 Berlin, Germany
- Institut für Physik, Brandenburgische Technische Universität Cottbus-Senftenberg , 03046 Cottbus, Germany
| | - Sascha Sadewasser
- International Iberian Nanotechnology Laboratory (INL) , 4715-330 Braga, Portugal
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21
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Impact of Wide-Ranging Nanoscale Chemistry on Band Structure at Cu(In, Ga)Se 2 Grain Boundaries. Sci Rep 2017; 7:14163. [PMID: 29074885 PMCID: PMC5658345 DOI: 10.1038/s41598-017-14215-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 10/04/2017] [Indexed: 11/08/2022] Open
Abstract
The relative chemistry from grain interiors to grain boundaries help explain why grain boundaries may be beneficial, detrimental or benign towards device performance. 3D Nanoscale chemical analysis extracted from atom probe tomography (APT) (10's of parts-per-million chemical sensitivity and sub-nanometer spatial resolution) of twenty grain boundaries in a high-efficiency Cu(In, Ga)Se2 solar cell shows the matrix and alkali concentrations are wide-ranging. The concentration profiles are then related to band structure which provide a unique insight into grain boundary electrical performance. Fluctuating Cu, In and Ga concentrations result in a wide distribution of potential barriers at the valence band maximum (VBM) (-10 to -160 meV) and the conduction band minimum (CBM) (-20 to -70 meV). Furthermore, Na and K segregation is not correlated to hampering donors, (In, Ga)Cu and VSe, contrary to what has been previously reported. In addition, Na and K are predicted to be n-type dopants at grain boundaries. An overall band structure at grain boundaries is presented.
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22
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Ishizuka S, Koida T, Taguchi N, Tanaka S, Fons P, Shibata H. Si-Doping Effects in Cu(In,Ga)Se 2 Thin Films and Applications for Simplified Structure High-Efficiency Solar Cells. ACS APPLIED MATERIALS & INTERFACES 2017; 9:31119-31128. [PMID: 28829112 DOI: 10.1021/acsami.7b09019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We found that elemental Si-doped Cu(In,Ga)Se2 (CIGS) polycrystalline thin films exhibit a distinctive morphology due to the formation of grain boundary layers several tens of nanometers thick. The use of Si-doped CIGS films as the photoabsorber layer in simplified structure buffer-free solar cell devices is found to be effective in enhancing energy conversion efficiency. The grain boundary layers formed in Si-doped CIGS films are expected to play an important role in passivating CIGS grain interfaces and improving carrier transport. The simplified structure solar cells, which nominally consist of only a CIGS photoabsorber layer and a front transparent and a back metal electrode layer, demonstrate practical application level solar cell efficiencies exceeding 15%. To date, the cell efficiencies demonstrated from this type of device have remained relatively low, with values of about 10%. Also, Si-doped CIGS solar cell devices exhibit similar properties to those of CIGS devices fabricated with post deposition alkali halide treatments such as KF or RbF, techniques known to boost CIGS device performance. The results obtained offer a new approach based on a new concept to control grain boundaries in polycrystalline CIGS and other polycrystalline chalcogenide materials for better device performance.
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Affiliation(s)
- Shogo Ishizuka
- Research Center for Photovoltaics, National Institute of Advanced Industrial Science and Technology (AIST) , 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
| | - Takashi Koida
- Research Center for Photovoltaics, National Institute of Advanced Industrial Science and Technology (AIST) , 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
| | - Noboru Taguchi
- Research Institute of Electrochemical Energy, National Institute of Advanced Industrial Science and Technology (AIST) , 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577, Japan
| | - Shingo Tanaka
- Research Institute of Electrochemical Energy, National Institute of Advanced Industrial Science and Technology (AIST) , 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577, Japan
| | - Paul Fons
- Nanoelectronics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST) , 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan
| | - Hajime Shibata
- Research Center for Photovoltaics, National Institute of Advanced Industrial Science and Technology (AIST) , 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
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23
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Handick E, Reinhard P, Wilks RG, Pianezzi F, Kunze T, Kreikemeyer-Lorenzo D, Weinhardt L, Blum M, Yang W, Gorgoi M, Ikenaga E, Gerlach D, Ueda S, Yamashita Y, Chikyow T, Heske C, Buecheler S, Tiwari AN, Bär M. Formation of a K-In-Se Surface Species by NaF/KF Postdeposition Treatment of Cu(In,Ga)Se 2 Thin-Film Solar Cell Absorbers. ACS APPLIED MATERIALS & INTERFACES 2017; 9:3581-3589. [PMID: 28058843 DOI: 10.1021/acsami.6b11892] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
A NaF/KF postdeposition treatment (PDT) has recently been employed to achieve new record efficiencies of Cu(In,Ga)Se2 (CIGSe) thin film solar cells. We have used a combination of depth-dependent soft and hard X-ray photoelectron spectroscopy as well as soft X-ray absorption and emission spectroscopy to gain detailed insight into the chemical structure of the CIGSe surface and how it is changed by different PDTs. Alkali-free CIGSe, NaF-PDT CIGSe, and NaF/KF-PDT CIGSe absorbers grown by low-temperature coevaporation have been interrogated. We find that the alkali-free and NaF-PDT CIGSe surfaces both display the well-known Cu-poor CIGSe chemical surface structure. The NaF/KF-PDT, however, leads to the formation of bilayer structure in which a K-In-Se species covers the CIGSe compound that in composition is identical to the chalcopyrite structure of the alkali-free and NaF-PDT absorber.
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Affiliation(s)
- Evelyn Handick
- Renewable Energy, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB) , Hahn-Meitner Platz 1, 14109 Berlin, Germany
| | - Patrick Reinhard
- Laboratory of Thin Films and Photovoltaics, Empa-Swiss Federal Laboratories for Materials and Science and Technology , Überlandstraße 129, 8600 Dübendorf, Switzerland
| | - Regan G Wilks
- Renewable Energy, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB) , Hahn-Meitner Platz 1, 14109 Berlin, Germany
- Energy Materials In-Situ Laboratory Berlin, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - Fabian Pianezzi
- Laboratory of Thin Films and Photovoltaics, Empa-Swiss Federal Laboratories for Materials and Science and Technology , Überlandstraße 129, 8600 Dübendorf, Switzerland
| | - Thomas Kunze
- Renewable Energy, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB) , Hahn-Meitner Platz 1, 14109 Berlin, Germany
| | - Dagmar Kreikemeyer-Lorenzo
- Institute for Photon Science and Synchrotron Radiation (IPS) and Institute for Chemical Technology and Polymer Chemistry (ITCP), Karlsruhe Institute of Technology (KIT) , Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Lothar Weinhardt
- Institute for Photon Science and Synchrotron Radiation (IPS) and Institute for Chemical Technology and Polymer Chemistry (ITCP), Karlsruhe Institute of Technology (KIT) , Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
- Department of Chemistry and Biochemistry, University of Nevada, Las Vegas (UNLV) , 4505 S. Maryland Parkway, Las Vegas, Nevada 89154-4003, United States
| | - Monika Blum
- Department of Chemistry and Biochemistry, University of Nevada, Las Vegas (UNLV) , 4505 S. Maryland Parkway, Las Vegas, Nevada 89154-4003, United States
| | - Wanli Yang
- Advanced Light Source (ALS), Lawrence Berkeley National Laboratory , 1 Cyclotron Road, Berkeley, California 94720, United States
| | - Mihaela Gorgoi
- Energy Materials In-Situ Laboratory Berlin, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , Albert-Einstein-Straße 15, 12489 Berlin, Germany
- Institute for Nanospectroscopy, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - Eiji Ikenaga
- SPring-8/JASRI , 1-1-1 Koto, Sayo-cho, Hyogo 679-5198, Japan
| | - Dominic Gerlach
- MANA/Nano-Electronics Materials Unit, National Institute for Materials Science , 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Shigenori Ueda
- Synchrotron X-ray Station at SPring-8 , NIMS. 1-1-1 Kouto, Sayo-cho, Hyogo 679-5148, Japan
- Quantum Beam Unit , NIMS, 1-2-1, Sengen, Tsukuba, Ibaraki 305-0047, Japan
| | - Yoshiyuki Yamashita
- MANA/Nano-Electronics Materials Unit, National Institute for Materials Science , 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Toyohiro Chikyow
- MANA/Nano-Electronics Materials Unit, National Institute for Materials Science , 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Clemens Heske
- Institute for Photon Science and Synchrotron Radiation (IPS) and Institute for Chemical Technology and Polymer Chemistry (ITCP), Karlsruhe Institute of Technology (KIT) , Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
- Department of Chemistry and Biochemistry, University of Nevada, Las Vegas (UNLV) , 4505 S. Maryland Parkway, Las Vegas, Nevada 89154-4003, United States
| | - Stephan Buecheler
- Laboratory of Thin Films and Photovoltaics, Empa-Swiss Federal Laboratories for Materials and Science and Technology , Überlandstraße 129, 8600 Dübendorf, Switzerland
| | - Ayodhya N Tiwari
- Laboratory of Thin Films and Photovoltaics, Empa-Swiss Federal Laboratories for Materials and Science and Technology , Überlandstraße 129, 8600 Dübendorf, Switzerland
| | - Marcus Bär
- Renewable Energy, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB) , Hahn-Meitner Platz 1, 14109 Berlin, Germany
- Energy Materials In-Situ Laboratory Berlin, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , Albert-Einstein-Straße 15, 12489 Berlin, Germany
- Institut für Physik und Chemie, Brandenburgische Technische Universität Cottbus-Senftenberg , Platz der Deutschen Einheit 1, 03046 Cottbus, Germany
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24
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Nicoara N, Lepetit T, Arzel L, Harel S, Barreau N, Sadewasser S. Effect of the KF post-deposition treatment on grain boundary properties in Cu(In, Ga)Se 2 thin films. Sci Rep 2017; 7:41361. [PMID: 28128351 PMCID: PMC5269666 DOI: 10.1038/srep41361] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 12/20/2016] [Indexed: 11/29/2022] Open
Abstract
Significant power conversion efficiency improvements have recently been achieved for thin-film solar cells based on a variety of polycrystalline absorbers, including perovskites, CdTe, and Cu(In,Ga)Se2 (CIGS). The passivation of grain boundaries (GBs) through (post-deposition) treatments is a crucial step for this success. For the case of CIGS, the introduction of a potassium fluoride post-deposition treatment (KF-PDT) has boosted their power conversion efficiency to the best performance of all polycrystalline solar cells. Direct and indirect effects of potassium at the interface and interface-near region in the CIGS layer are thought to be responsible for this improvement. Here, we show that also the electronic properties of the GBs are beneficially modified by the KF-PDT. We used Kelvin probe force microscopy to study the effect of the KF-PDT on the CIGS surface by spatially resolved imaging of the surface potential. We find a clear difference for the GB electronic properties: the KF-PDT increases the band bending at GBs by about 70% and results in a narrower distribution of work function values at the GBs. This effect of the KF-PDT on the GB electronic properties is expected to contribute to the improved efficiency values observed for CIGS thin-film solar cells with KF-PDT.
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Affiliation(s)
- N Nicoara
- INL - International Iberian Nanotechnology Laboratory, Av. Mestre José Veiga s/n, 4715-330 Braga, Portugal
| | - Th Lepetit
- Institut des Matériaux Jean Rouxel (IMN) - UMR6502, Université de Nantes, CNRS, 2 rue de la Houssinière, BP 32229, 44322 Nantes Cedex 3, France
| | - L Arzel
- Institut des Matériaux Jean Rouxel (IMN) - UMR6502, Université de Nantes, CNRS, 2 rue de la Houssinière, BP 32229, 44322 Nantes Cedex 3, France
| | - S Harel
- Institut des Matériaux Jean Rouxel (IMN) - UMR6502, Université de Nantes, CNRS, 2 rue de la Houssinière, BP 32229, 44322 Nantes Cedex 3, France
| | - N Barreau
- Institut des Matériaux Jean Rouxel (IMN) - UMR6502, Université de Nantes, CNRS, 2 rue de la Houssinière, BP 32229, 44322 Nantes Cedex 3, France
| | - S Sadewasser
- INL - International Iberian Nanotechnology Laboratory, Av. Mestre José Veiga s/n, 4715-330 Braga, Portugal
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Strategy for enhancing the solar-driven water splitting performance of TiO 2 nanorod arrays with thin Zn(O,S) passivated layer by atomic layer deposition. Electrochim Acta 2016. [DOI: 10.1016/j.electacta.2016.09.020] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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