Article
Chemistry, Physical
Natalia M. Martin, Tobias Torndahl, Erik Wallin, Konstantin A. Simonov, Hakan Rensmo, Charlotte Platzer-Bjorkman
Summary: The study investigates the impact of postdeposition treatments on ACIGS solar cell performance, finding that different alkali metal fluoride treatments can modify the surface composition of the ACIGS absorber layer, thereby influencing device behavior.
ACS APPLIED ENERGY MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Yu-Han Chang, Romain Carron, Mario Ochoa, Ayodhya N. Tiwari, James R. Durrant, Ludmilla Steier
Summary: This study investigates the impact of NaF and RbF postdeposition treatments on minority carrier dynamics in Cu(In,Ga)Se-2 solar cells using transient absorption spectroscopy. NaF PDT improves electron recombination lifetimes, while the effectiveness of RbF PDT decreases with higher Ga-concentrations. Additionally, both alkali PDTs promote electron mobility in the absorber region with large grains.
ADVANCED FUNCTIONAL MATERIALS
(2021)
Article
Nanoscience & Nanotechnology
Woo-Jung Lee, Dae-Hyung Cho, Jae-Hyung Wi, Jong Hun Yu, Woo-Ju Kim, Chul Kang, Seong Jun Kang, Yong-Duck Chung
Summary: The highest efficiency of CIGS solar cells was achieved at a KF PDT process time of 50s, where the K-In-Se phase formed is beneficial for solar cell performance. Additionally, photocarrier transport is more effective at low barrier heights.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Energy & Fuels
Jessica de Wild, Gizem Birant, Raghavendran Thiruvallur Eachambadi, Thierry Kohl, Dilara G. Buldu, Guy Brammertz, Jean V. Manca, Marc Meuris, Jef Poortmans, Bart Vermang
Summary: The study investigates the passivation of the Cu(In,Ga)Se-2 (CIGS)/Mo back contact using AlOx to reduce recombination at the interface. It was found that the postdeposition treatment using RbF deteriorates performance due to the formation of an injection barrier at the front and reduced acceptor concentration. Analysis with time-of-flight secondary ion mass spectroscopy revealed higher Na concentration at the AlOx/Mo back contact.
Article
Nanoscience & Nanotechnology
Longlong Zeng, Linquan Zhang, Yunfeng Liang, Chunhong Zeng, Zeyu Qiu, Haofeng Lin, Ruijiang Hong
Summary: In this study, a novel low-temperature fabrication strategy of CIGS solar cells using the bismuth (Bi)-doping method is reported, and its growth-promoting mechanism is studied. Bi doping significantly improves grain growth and enhances the efficiency of solar cells. The formation of Cu-Bi-Se compounds promotes the crystallization of CIGS absorbers and enhances carrier transport. Bi doping also increases the open circuit voltage of the solar cells.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Nanoscience & Nanotechnology
Tomas S. Lopes, Jessica de Wild, Celia Rocha, Andre Violas, Jose M. Cunha, Jennifer P. Teixeira, Marco A. Curado, Antonio J. N. Oliveira, Jerome Borme, Gizem Birant, Guy Brammertz, Paulo A. Fernandes, Bart Vermang, Pedro M. P. Salome
Summary: The study demonstrated the simultaneous implementation of potassium fluoride (KF) post-deposition treatment (PDT) and a rear interface passivation strategy on ultrathin Cu(In,Ga)Se-2 (CIGS) solar cells for the first time. Electrical measurements and simulations suggested that under specific conditions, devices with only KF-PDT treatment may outperform those with rear interface passivation alone. By combining KF-PDT and rear interface passivation, there was a significant enhancement in open-circuit voltage and reduction in recombination losses, leading to improved charge carrier lifetime in the studied devices.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Energy & Fuels
Alexandra M. Bothwell, Jake Wands, Michael F. Miller, Ana Kanevce, Stefan Paetel, Polyxeni Tsoulka, Thomas Lepetit, Nicolas Barreau, Nicholas Valdes, William Shafarman, Angus Rockett, Aaron R. Arehart, Darius Kuciauskas
Summary: Voltage losses are a major efficiency limitation in Cu(In,Ga)Se-2 thin-film solar cells. This study analyses the voltage loss of Cu(In,Ga)Se-2 solar cells fabricated at three institutions with variations in process, bandgap, absorber structure, postdeposition treatment (PDT), and efficiency. Nonradiative voltage losses dominate and are mainly caused by Shockley-Read-Hall charge carrier recombination. It is shown that significant improvements in bulk lifetime are achieved with alkali PDT processed absorbers, leading to reduced nonradiative recombination.
Article
Materials Science, Multidisciplinary
Leiyi Sun, Hui Wang, Ruihu Wang, Zhuo Peng, Baozeng Zhou, Yujie Yuan, Liyong Yao, Jinlian Bi, Yupeng Xing, Wei Li
Summary: In this study, the effect of interfacial recombination on CIGSe solar cells was investigated by using oxygen-doped Mo(OxSe1-x)2. By optimizing the band alignment and adjusting the band gap of the material, the back interface recombination was effectively reduced, leading to an improved performance of the solar cells.
Article
Energy & Fuels
Omar Ramirez, Maud Bertrand, Alice Debot, Daniel Siopa, Nathalie Valle, Jorg Schmauch, Michele Melchiorre, Susanne Siebentritt
Summary: Research has shown that postdeposition treatments with potassium fluoride can enhance the quasi-Fermi level splitting of Cu(In,Ga)Se-2 single crystals, especially in low-gallium Cu-poor materials. Secondary ion mass spectrometry confirms the transport of potassium through the grain interiors. Additionally, a type inversion from n to p in potassium fluoride-treated samples indicates the dopant role of potassium in altering the optoelectronic properties of Cu(In,Ga)Se-2.
Article
Nanoscience & Nanotechnology
Takehiko Nagai, Jiro Nishinaga, Hitoshi Tampo, Shinho Kim, Kazuhiro Hirayama, Tatsuo Matsunobe, Guanzhong Chen, Yuya Ide, Shogo Ishizuka, Hajime Shibata, Shigeru Niki, Norio Terada
Summary: In this study, we investigated the band alignments at CdS/epitaxial CuInxGa1-xSe2 (epi-CIGSe) and epi-CIGSe/GaAs heterointerfaces for solar cell applications using photoemission spectroscopy techniques. The impact of KF postdeposition treatment (KF-PDT) on the band alignment at the CdS/epi-CIGSe front heterointerface was clarified. We found that KF-PDT changed the conduction band alignment by altering the electron affinity and ionization potential of the epi-CIGSe surface. Additionally, band alignment at the epi-CIGSe/GaAs rear heterointerface was investigated, showing the formation of electron barriers and a hole accumulation layer.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Energy & Fuels
Ryotaro Fukuda, Takahito Nishimura, Akira Yamada
Summary: The behavior of carriers for an electron-beam-induced current (EBIC) evaluation in polycrystalline Cu(In, Ga)Se-2 (CIGS) thin-film solar cells was experimentally and theoretically analyzed. The analysis revealed four features in the EBIC signal profiles of the CIGS layers: peaks at grain boundaries (GBs), narrowed peaks near the surface, shifted peaks near the surface, and double peaks at the GBs and surface. These findings will contribute to a comprehensive understanding of the carrier transport mechanism in polycrystalline CIGS, which is crucial for achieving high-efficiency CIGS solar cells.
PROGRESS IN PHOTOVOLTAICS
(2023)
Article
Materials Science, Multidisciplinary
Dayoung Yoo, Mao Zhang, Changsoon Choi, Byungha Shin, Yoon-Hwae Hwang, Yangdo Kim, Dongyun Lee
Summary: The mechanical behavior and crack characteristics of GIGS films were studied, revealing higher fracture toughness than soda-lime glass, predominantly intergranular fracture, and the presence of Palmqvist radial and lateral cracks.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2021)
Article
Chemistry, Physical
Min Jeong Shin, Ahreum Lee, Ara Cho, Kihwan Kim, Seung Kyu Ahn, Joo Hyung Park, Jinsu Yoo, Jae Ho Yun, Jihye Gwak, Donghyeop Shin, Inyoung Jeong, Jun-Sik Cho
Summary: This study presents the material properties and performance characteristics of semitransparent ultrathin CIGS solar cells prepared on two types of transparent conducting oxide rear contacts using a single-stage co-evaporation method. The results show that the single-stage process is effective for fabricating high-performance semitransparent CIGS solar devices. Light management plays an important role in devices with ultrathin CIGS absorbers, with a textured PDMS layer enhancing light absorption properties. The device prepared on a flat In2O3:Sn rear contact with a textured PDMS layer exhibits superior performance, with a conversion efficiency of 10.5% and an average visible transmittance of 12.3%.
Article
Green & Sustainable Science & Technology
Jakob Bombsch, Enrico Avancini, Romain Carron, Evelyn Handick, Raul Garcia-Diez, Claudia Hartmann, Roberto Felix, Daniel Abou-Ras, Shigenori Ueda, Regan G. Wilks, Marcus Baer
Summary: Research shows that postdeposition treatments with alkali fluoride can influence the chemical and electronic structure of CIGSe absorbers, resulting in a copper-deficient surface region and accumulation of Rb and depletion of Na on the backside.
ADVANCED ENERGY AND SUSTAINABILITY RESEARCH
(2021)
Article
Energy & Fuels
Lung-Hsin Tu, Chung-Hao Cai, Chih-Huang Lai
Summary: By forming the ordered vacancy compound phase at the beginning of the selenization process and controlling the Se partial pressure, interlayer TiN thickness, and carrier concentration, a high efficiency of CIGSe solar cells has been achieved.
Article
Chemistry, Physical
Shogo Ishizuka, Jiro Nishinaga, Kosuke Beppu, Tsuyoshi Maeda, Fuuka Aoyagi, Takahiro Wada, Akira Yamada, Jakapan Chantana, Takahito Nishimura, Takashi Minemoto, Muhammad Monirul Islam, Takeaki Sakurai, Norio Terada
Summary: This paper reviews current issues in physical and chemical studies of CISe-based materials and devices, focusing on areas such as correlations between Cu-deficient phases and alkali-metals effects, applications to lightweight and flexible solar minimodules, single-crystalline epitaxial Cu(In,Ga)Se-2 films and devices, differences between Cu(In,Ga)Se-2 and Ag(In,Ga)Se-2 materials, wide-gap CuGaSe2 films and devices, all-dry processed CISe-based solar cells with high photovoltaic efficiencies, and fundamental studies on open circuit voltage loss analysis and energy band structure at the interface.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
Article
Materials Science, Multidisciplinary
Jiro Nishinaga, Shogo Ishizuka
Summary: This study investigates the effects of KF-PDT and NaF doping on the conversion efficiency of Cu(In,Ga)Se-2(CIGS) solar cells. It is found that these treatments have positive effects on efficiency even when using Cu stoichiometric CIGS layers. The study also shows that NaF doping and KF-PDT increase the minority carrier lifetimes, similar to polycrystalline CIGS solar cells.
Article
Nanoscience & Nanotechnology
Takehiko Nagai, Jiro Nishinaga, Hitoshi Tampo, Shinho Kim, Kazuhiro Hirayama, Tatsuo Matsunobe, Guanzhong Chen, Yuya Ide, Shogo Ishizuka, Hajime Shibata, Shigeru Niki, Norio Terada
Summary: In this study, we investigated the band alignments at CdS/epitaxial CuInxGa1-xSe2 (epi-CIGSe) and epi-CIGSe/GaAs heterointerfaces for solar cell applications using photoemission spectroscopy techniques. The impact of KF postdeposition treatment (KF-PDT) on the band alignment at the CdS/epi-CIGSe front heterointerface was clarified. We found that KF-PDT changed the conduction band alignment by altering the electron affinity and ionization potential of the epi-CIGSe surface. Additionally, band alignment at the epi-CIGSe/GaAs rear heterointerface was investigated, showing the formation of electron barriers and a hole accumulation layer.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Energy & Fuels
Kikuo Makita, Yukiko Kamikawa, Hidenori Mizuno, Ryuji Oshima, Yasushi Shoji, Shogo Ishizuka, Ralph Mueller, David Lackner, Frank Dimroth, Takeyoshi Sugaya
Summary: A highly efficient InGaP/Al$_0.06$Ga$_0.94$As//CIGSe three-junction solar cell was successfully fabricated using a new smart stack technology, achieving a total efficiency of 28.06%, the highest efficiency ever reported for GaAs//CIGSe-based tandem solar cells.
IEEE JOURNAL OF PHOTOVOLTAICS
(2022)
Article
Energy & Fuels
Kikuo Makita, Yukiko Kamikawa, Takashi Koida, Hidenori Mizuno, Ryuji Oshima, Yasushi Shoji, Shogo Ishizuka, Tatsuya Takamoto, Takeyoshi Sugaya
Summary: This study presents a highly efficient InGaP/GaAs//CIGSe three-junction solar cell with an efficiency of 29.3% for the aperture area, the highest reported for GaAs//CIGSe-based tandem solar cells. The improved performance is achieved by using a modified smart stack technology and a specialized CIGSe cell with a flattened surface and a thin In2O3;Ce,H transparent conducting oxide layer.
PROGRESS IN PHOTOVOLTAICS
(2023)
Article
Energy & Fuels
Yukiko Kamikawa, Taizo Masuda, Jiro Nishinaga, Shogo Ishizuka
Summary: This study investigated the influence of Ar background pressure on the properties of Mo back contact on polyimide films. High Ar pressure caused crack formation in the Mo layer and decreased fill factor, while reducing the Ar pressure improved the fill factor. Additionally, the stress condition of Mo also affected the thermal diffusion of alkali metal.
Article
Physics, Applied
Jiro Nishinaga, Manabu Togawa, Masaya Miyahara, Kosuke Itabashi, Hironori Okumura, Masataka Imura, Yukiko Kamikawa, Shogo Ishizuka
Summary: Radiation tolerance of Cu(In,Ga)Se-2 (CIGS) solar cells was investigated for application in extremely-high-radiation environments. The cells deteriorated after high-energy proton irradiation but could still generate power. Recombination centers in CIGS layers increased after irradiation, but heat-light annealing partially passivated them. Dark annealing also had a beneficial effect on passivating recombination centers, even with thicker CIGS layers.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Physics, Applied
Hajime Shibata, Jiro Nishinaga, Yukiko Kamikawa, Hitoshi Tampo, Takehiko Nagai, Takashi Koida, Shogo Ishizuka, Toshimitsu Mochizuki, Masafumi Yamaguchi
Summary: The optoelectronic reciprocity theorem relates electroluminescence (EL) and photovoltaic external quantum efficiency in solar cells and is crucial for understanding solar cell operation and device evaluation. It also allows for estimating the open-circuit voltage (VOC) using the external radiative efficiency (riext) obtained from EL emission intensity. This study confirms the validity of the optoelectronic reciprocity theorem for high-efficiency CuIn1-xGaxSe2 (CIGS) solar cells and demonstrates that the diode ideality factor is unity for band-edge emission due to direct recombination.
PHYSICAL REVIEW APPLIED
(2023)
Article
Physics, Applied
Thomas Paul Weiss, Omar Ramirez, Stefan Paetel, Wolfram Witte, Jiro Nishinaga, Thomas Feurer, Susanne Siebentritt
Summary: Cu(In,Ga)Se2-based solar cells achieve power conversion efficiencies exceeding 23%. However, the fill factor of these cells is relatively low due to diode factors greater than 1, mainly caused by metastable defects in the Cu(In,Ga)Se2 alloy. Excitation-dependent photoluminescence measurements reveal that the increased diode factor can be well explained by the model of metastable defects. Optically measured diode factors impose a lower limit on the electrical diode factor of finished solar cells. Ag alloying provides a pathway to increase fill factors and efficiencies for Cu(In,Ga)Se2-based solar cells.
PHYSICAL REVIEW APPLIED
(2023)
Article
Chemistry, Physical
Jakapan Chantana, Bobur Ergashev, Yu Kawano, Yukiko Kamikawa, Shogo Ishizuka, Takashi Minemoto
Summary: CIGSe solar cells were fabricated on SLG substrates with the structure of Al/Ni/sputtered Zn(0.88)Mg(0.12)O:Al TCO/sputtered Zn1-xMgxO 2nd buffer/CdS 1st buffer/CIGSe/Mo/SLG. The impact of CBO2 between CIGSe absorber and Zn1-xMgxO 2nd buffer on cell performance and carrier recombination was investigated experimentally and theoretically. The optimization of CBO2 reduced carrier recombination, improved band bending, and increased the conversion efficiency up to 20.0%. With an antireflective coating layer, the CIGSe solar cell achieved a conversion efficiency of 21.1% with the optimized CBO2.
ACS APPLIED ENERGY MATERIALS
(2023)
Article
Engineering, Electrical & Electronic
Shogo Ishizuka, Yukiko Kamikawa, Jiro Nishinaga
Summary: This communication presents the prospects of Cu(In,Ga)Se-2 (CIGS)-based lightweight and flexible photovoltaic devices, discusses the current status of flexible CIGS minimodules and future directions to enhance their efficiency, and explores the effects of cell separation edges on device performance.
NPJ FLEXIBLE ELECTRONICS
(2022)
