Article
Chemistry, Physical
Adam Hultqvist, Jan Keller, Natalia M. Martin, Fredrik Larsson, Tobias Torndahl
Summary: Two inorganic electron-selective layers (ESLs), Sn1-xGexOy (TGO) and Zn1-xGexOy (ZGO), were developed using atomic layer deposition (ALD) for compatibility with (Ag,Cu)(In,Ga)Se-2 (ACIGS) solar cells. The efficiency of the ACIGS solar cell peaked for an intermediate Ge content, and using good TGO and ZGO compositions gave efficiencies of up to 14.8% and 17.0% respectively. The study identified key properties required for a good ACIGS solar cell ESL and made suggestions based on the previous success of Zn1-xSnxOy (ZTO).
ACS APPLIED ENERGY MATERIALS
(2023)
Article
Chemistry, Physical
Sung-Tae Kim, Vishwa Bhatt, Ye-Chan Kim, Ho-Jung Jeong, Ju-Hyung Yun, Jae-Hyung Jang
Summary: The study demonstrates that Na diffusion can enhance the performance of CIGSe thin-film solar cells by promoting the growth of MoSe2 layer at CIGSe/Mo interface and improving junction properties, leading to an increased photo-conversion efficiency.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Energy & Fuels
Jan Keller, Hisham Aboulfadl, Lars Stolt, Olivier Donzel-Gargand, Marika Edoff
Summary: This contribution investigates the potential of RbF postdeposition treatment on ACIGS solar cells. It is found that while the open-circuit voltage and short-circuit current density can be improved, the fill factor decreases. However, for some stoichiometric samples, the drop in fill factor can be avoided, resulting in higher efficiencies. Extensive material analysis reveals that the treatment leads to modifications in the absorber layer and restricted diffusion of rubidium. A thin RbInSe2 surface layer is also suggested.
Article
Energy & Fuels
Jan Keller, Patrick Pearson, Nina Shariati Nilsson, Olof Stolt, Lars Stolt, Marika Edoff
Summary: The study focused on the impact of absorber stoichiometry in ACIGS solar cells with bandgaps greater than 1.40 eV, showing that moving away from AgGaSe2 composition can reduce ordered vacancy compounds, leading to improved device performance. An inverse correlation between V-OC and J(SC) was observed, with capacitance profiling revealing enhanced carrier collection in fully depleted samples. Additionally, the measurement of a solar cell with V-OC = 0.916 V at E-g = 1.46 eV represents the highest reported value for this bandgap to date.
Article
Energy & Fuels
Bing Li, Aimei Zhao, Dongmei Xiang, Zhuo Peng, Yujie Yuan, Yupeng Xing, Liyong Yao, Jinlian Bi, Wei Li
Summary: In this study, an Ag buffer layer was used to eliminate the nonuniform distribution of Cu on Mo, resulting in improved crystallinity and performance of ACIGSe absorber and solar cells.
Article
Energy & Fuels
Ara Cho, Shahara Banu, Soomin Song, Donghyeop Shin, Inchan Hwang, Inyoung Jeong, Young -Joo Eo, Seung Kyu Ahn, Kihwan Kim
Summary: Large-scale synthesis of (Ag,Cu)(In,Ga)Se2 (ACIGS) thin films was achieved using a hybrid ink method. The use of Se@Ag2Se core-shell allowed for the formation of ACIGS thin films at lower reaction temperature and shorter reaction time. Sb-doping improved the performance of ACIGS solar cells, increasing the conversion efficiency and carrier concentration.
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
Nanoscience & Nanotechnology
Hisham Aboulfadl, Kostiantyn Sopiha, Jan Keller, Jes K. Larsen, Jonathan J. S. Scragg, Clas Persson, Mattias Thuvander, Marika Edoff
Summary: Through experimental and theoretical studies, it has been found that there is a clear trend of increased alkali bulk solubility with the silver concentration in Cu(In,Ga)Se-2 absorbers, which can enhance the performance of photovoltaic devices.
ACS APPLIED MATERIALS & INTERFACES
(2021)
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
Energy & Fuels
Jessica de Wild, Gizem Birant, Guy Brammertz, Marc Meuris, Jef Poortmans, Bart Vermang
Summary: This study focused on the growth of ultrathin Cu(In,Ga)Se-2 (CIGS) absorber layers on Ag/AlOx stacks, resulting in improved efficiency of solar cells to almost 12%, along with enhanced fill factor, open circuit voltage, and short circuit current density. The addition of the stack led to improvements in photoluminescence (PL), time resolved PL, and an increase in light scattering and surface roughness. Furthermore, it was found that Ag was incorporated throughout the CIGS layer, and residues of the Ag/AlOx stack were observed on the Mo back contact, affecting surface roughness and scattering properties. An ammonia sulfide etching step further enhanced the efficiency to 11.7%.
Article
Optics
Zhaojing Hu, Yunxiang Zhang, Shuping Lin, Shiqing Cheng, Zhichao He, Chaojie Wang, Zhiqiang Zhou, Fangfang Liu, Yun Sun, Wei Liu
Summary: Different Ag treatment processes were employed to enhance the quality of CIGS thin films deposited at low temperatures, demonstrating improvements in crystallinity and device efficiency due to Ag precursor and surface treatment. The former had a more significant impact, with a reduction in Urbach energy observed with Ag doping. This study aims to provide a feasible Ag-doping process for high-quality CIGS films in low-temperature deposition processes.
CHINESE OPTICS LETTERS
(2021)
Article
Energy & Fuels
Shih-Chi Yang, Jordi Sastre, Maximilian Krause, Xiaoxiao Sun, Ramis Hertwig, Mario Ochoa, Ayodhya N. Tiwari, Romain Carron
Summary: This study explores the potential of producing high-efficiency solar cells at low temperatures (<=450 degrees C) by alloying CIGS with Ag to form ACIGS solar cells, which achieved an efficiency of 20.1%. Minimal efficiency degradation was observed for ACIGS absorbers deposited at lower temperatures, in contrast to more significant degradation in CIGS devices. Advanced characterization techniques revealed that the improved morphology, reduced tail states, and higher doping density in ACIGS absorbers were the key factors contributing to the higher efficiency of ACIGS devices compared to CIGS devices.
Article
Physics, Multidisciplinary
Rong Wang, Baoying Dou, Yifeng Zheng, Su-Huai Wei
Summary: In this study, the structural, electronic, and defect properties of AgInSe2, AgGaSe2, and their alloys were investigated using first-principles calculations. The results suggest that alloy engineering can enhance the power conversion efficiency of the solar cell absorber, and a new buffer layer material is needed for better electron transport in the solar cell.
SCIENCE CHINA-PHYSICS MECHANICS & ASTRONOMY
(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
Energy & Fuels
Diego A. Garzon, Christian Rossi, Ishwor Khatri, Francesco Soggia, Ihsan Caha, Francis Leonard Deepak, Diego Colombara, Sascha Sadewasser
Summary: The formation of Cd-free Zn1-xSnxOy (ZTO) thin film buffer layers for CIGSe solar cells was studied using chemical bath deposition. By modifying the deposition procedure, flatter ZTO films were obtained with inhibited columnar growth. Increasing the concentration of Sn in the chemical bath resulted in a nontrivial increase in the bandgap. Using a 20% Sn concentration, the CIGSe solar cells achieved similar performance to those with a CdS buffer layer, with a maximum efficiency of 10.4% and an average efficiency of 9%.
Article
Materials Science, Multidisciplinary
Yuta Nakagawa, Kazuhiro Gotoh, Tetsuya Inoue, Yasuyoshi Kurokawa, Noritaka Usami
Summary: By controlling the thickness of the TiOx layer and using the Mg interlayer, excellent surface passivation and transport properties can be achieved, resulting in improved open-circuit voltage and fill factor of the solar cells.
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
(2021)
Article
Physics, Applied
Yasuyoshi Kurokawa, Takamasa Yoshino, Kazuhiro Gotoh, Satoru Miyamoto, Noritaka Usami
Summary: BaSi2 homojunction diodes on Nb-doped TiO2 coated glass substrates were successfully fabricated using aluminum-induced crystallization (AIC) and a two-step evaporation method. Raman scattering spectra confirmed the growth of BaSi2 on TiO2:Nb, and the formation of BaSi2 diodes was observed at temperatures ranging from 475°C to 525°C during AIC. The photoresponsivity of the diodes peaked at a wavelength of 950 nm, corresponding to the bandgap of BaSi2, with the highest value obtained at an AIC temperature of 500°C. The results also showed that larger grain size in AIC-Si contributed to the improved quality and performance of BaSi2 thin films.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2022)
Article
Nanoscience & Nanotechnology
Michinobu Fujiwara, Kazuma Takahashi, Yoshihiko Nakagawa, Kazuhiro Gotoh, Takashi Itoh, Yasuyoshi Kurokawa, Noritaka Usami
Summary: The effect of low growth rate deposition (LGD) of BaSi2 on the film quality and performance of silicon heterojunction solar cells was investigated. It was found that LGD improved the crystalline structure and performance of the solar cells, with a maximum conversion efficiency of 10.62%. This improvement is attributed to the rearrangement of atoms during LGD.
Article
Energy & Fuels
Yuqing Li, Hitoshi Sai, Takuya Matsui, Zhihao Xu, Van Hoang Nguyen, Yasuyoshi Kurokawa, Noritaka Usami
Summary: This article introduces a method to fabricate nanometer-sized pyramids and investigates their application in silicon solar cells. The experimental results demonstrate that Si nanopyramids have lower reflectance and smaller etching margin, which can improve the performance of the cells while maintaining excellent surface passivation and carrier transport properties.
Article
Physics, Applied
Haitao Wang, Yasuyoshi Kurokawa, Kazuhiro Gotoh, Shinya Kato, Shigeru Yamada, Takashi Itoh, Noritaka Usami
Summary: Effective strategies for improving the performance of a droplet-based electricity generator (DEG) are proposed, including introducing an intermediate layer of cyclic transparent optical polymer (CYTOP) by adjusting the thickness, injecting ionized ions into the surface, and increasing the surface area. Positive effects of the introduction of a CYTOP layer on outputs, especially with a greater thickness, surface ionized-air modification, and larger surface area, were observed, which could promote the practical application of DEG in energy harvesting.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Physics, Applied
Keisuke Shibata, Shinya Kato, Masashi Kurosawa, Kazuhiro Gotoh, Satoru Miyamoto, Noritaka Usami, Yasuyoshi Kurokawa
Summary: Boron-doped silicon nanocrystals/amorphous silicon oxide multilayers were prepared and their properties were investigated. The electrical conductivity of the multilayers increased with a thickness of the a-SiOx layer and saturated at a certain value. The Seebeck coefficient remained constant and the thermal conductivity was independent of the a-SiOx layer thickness, with a maximum power factor obtained at a specific thickness.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Hao Luo, Van Hoang Nguyen, Kazuhiro Gotoh, Saya Ajito, Tomohiko Hojo, Yasuyoshi Kurokawa, Eiji Akiyama, Noritaka Usami
Summary: This study investigates the effect of post-oxidizing treatment (POT) on the structural, optical, and passivation performances of titanium oxide coated crystalline Si (c-Si) heterostructures prepared by the solution process. The results show that POT improves the passivation performance by oxidizing the TiOx film, c-Si surface, and forming POx.
Article
Materials Science, Multidisciplinary
Yuta Shiratori, Shinsuke Miyajima
Summary: This study investigated the properties of sputtered nanocrystalline gallium nitride (nc-GaN) and its potential as an electron selective contact in a silicon heterojunction (SHJ) solar cell. Simulation of the nc-GaN/crystalline silicon (c-Si) heterojunction was performed based on the analysis of deposited nc-GaN films and nc-GaN/c-Si heterojunction devices. The simulation results indicated that using nc-GaN with an electron concentration greater than 5 x 1018 cm-3 and a metal contact with a work function less than 3.9 eV is crucial for obtaining good solar cell performance.
Article
Physics, Applied
Shohei Fukaya, Kazuhiro Gotoh, Takuya Matsui, Hitoshi Sai, Yasuyoshi Kurokawa, Noritaka Usami
Summary: In this study, a simple method was proposed to investigate the effect of metallization on the surface passivation of titanium oxide (TiO x )/Si heterostructures. The relationship between implied open-circuit voltage (iV (OC)) and photoluminescence (PL) intensity imaging of solar cell precursors before metallization was studied using PL imaging technique. Based on this relationship, the quantitative evaluation of the change in iV (OC) before and after metallization on the TiO x was performed. The results showed that the iV (OC) predicted by the PL measurement decreased by 23-104 mV after metal deposition and had a good agreement with the measured V (OC) in the finished solar cells. The evaluation of iV (OC) by PL measurement provides a useful prediction of V (OC) after metallization, which helps in analyzing the passivation degradation induced by metallization.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Physics, Applied
Naoki Aso, Haruto Tani, Rintaro Fukamizu, Hirofumi Shimizu, Shinsuke Miyajima
Summary: The moisture absorption and TbCl3 doping of CsPbBr3 thin films were investigated to improve carrier transport properties. Post-deposition moisture-absorbing treatment was found to enhance the carrier diffusion length, particularly under a relative humidity of 20%-40%. TbCl3 doping during thermal evaporation affected the film structure, with excessive doping resulting in the formation of CsPb2Br5 additional phase, while a small amount (1%) improved carrier diffusion length. Moisture-absorbing treatment and TbCl3 doping show promise in enhancing the optoelectronic properties of CsPbBr3.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Physics, Applied
Rintaro Fukamizu, Naoki Aso, Yuta Shiratori, Shinsuke Miyajima
Summary: Nanocrystalline gallium nitride (nc-GaN) layers were deposited by RF magnetron sputtering as the electron transport layer of the cesium lead bromide (CsPbBr3) photovoltaic power converter. The study investigated the structural and electrical properties of the nc-GaN layers and found that substrate heater temperature plays a crucial role in determining the electrical conductivity. CsPbBr3 photovoltaic power converters with nc-GaN electron transport layers exhibited good photovoltaic performance, with the highest conversion efficiency of 5.56% achieved at a substrate heater temperature of 550 degrees C. The estimated conversion efficiency under blue light with a wavelength of 450 nm was 28.8%.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Physics, Applied
Noboru Yamaguchi, Shasha Li, Shinsuke Miyajima
Summary: In this study, tunnel oxide passivated contact (TOPCon) structures using highly doped n-type polycrystalline silicon were fabricated for SiH4-free fabrication process of high-efficiency silicon solar cells. The researchers investigated the structural and electrical properties of the highly doped n-type poly-Si layers and optimized the ion implantation process. The surface passivation quality of the TOPCon structure was also evaluated. The research results demonstrate the potential of SiH4-free fabrication of silicon solar cells with a TOPCon structure.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Physics, Applied
Kazuhiro Gotoh, Ryo Ozaki, Motoo Morimura, Aki Tanaka, Yoshiko Iseki, Kyotaro Nakamura, Kazuo Muramatsu, Yasuyoshi Kurokawa, Yoshio Ohshita, Noritaka Usami
Summary: We investigated the effect of B2H6 plasma treatment on p-type hydrogenated amorphous silicon (p-a-Si:H) surfaces for high-performance silicon heterojunction (SHJ) solar cells. The boron concentration at the p-a-Si:H surface increased after the B2H6 plasma treatment, and the specific contact resistance decreased by about one-third. The power conversion efficiency of SHJ solar cells improved due to increased fill factor (FF) resulting from decreased series resistance and increased shunt resistance, which was attributed to the enhanced upward band bending at the heterointerface between transparent conductive oxide (TCO) and p-a-Si:H caused by the B2H6 plasma treatment.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Engineering, Electrical & Electronic
Yasuyoshi Kurokawa, Kaisei Sato, Keisuke Shibata, Shinya Kato, Satoru Miyamoto, Kazuhiro Gotoh, Takashi Itoh, Noritaka Usami
Summary: By thermal evaporation of Mg and face-to-face annealing (FTFA), Mg2Si thin films were obtained on a crystalline Si substrate and a P-doped hydrogenated amorphous Si thin films on a quartz substrate. FTFA suppressed Mg evaporation, Mg2Si oxidation, and Mg2Si decomposition, resulting in the formation of polycrystalline Mg2Si thin film with large grain size. The effects of annealing temperature (TA) on crystal structure and thermoelectric properties of Mg2Si thin films were investigated. A relatively high ZT value of 0.68 was achieved at 712 K for a sample prepared at TA = 623 K, attributed to increased electrical conductivity, high Seebeck coefficient of -235 mu V center dot K-1, and low thermal conductivity of 1.4-1.7 W center dot m- 1 center dot K- 1.
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
(2023)
Article
Chemistry, Multidisciplinary
Yuqing Li, Hitoshi Sai, Calum Mcdonald, Zhihao Xu, Yasuyoshi Kurokawa, Noritaka Usami, Takuya Matsui
Summary: This study investigates the influence of nanoscale Si pyramid textures on the performance of perovskite/Si tandem solar cells. It is found that excessive texture size leads to non-uniform top-cell formation and reduced performance. However, reducing the texture size within a certain range can suppress reflection and enhance the open-circuit voltage and current of the cell.
ADVANCED MATERIALS INTERFACES
(2023)
