Dual-junction GaAs solar cells and their application to smart stacked III–V//Si multijunction solar cells

Sugaya, Takeyoshi; Tayagaki, Takeshi; Aihara, Taketo; Makita, Kikuo; Oshima, Ryuji; Mizuno, Hidenori; Nagato, Yuki; Nakamoto, Takashi; Okano, Yoshinobu

doi:10.7567/apex.11.052301

Cited by 14 publications

(9 citation statements)

References 26 publications

(31 reference statements)

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“…Regarding the methods to construct III–V-on-Si architectures, a variety of studies have been reported. One of the most straightforward approaches would be the heteroepitaxial growth of GaAs-relevant materials on c-Si substrates; , however, despite the progress of elaborative buffer layer techniques to compensate for the difference in lattice constants and thermal expansion coefficients between GaAs and Si, the layer quality achieved with this type of approach remains a challenge. ,− Alternatively, bonding-based approaches have gained increasing attention, − and as previously mentioned, impressive results have already been obtained by mechanically stacked four-terminal tandems and surface-activation-bonded two-terminal tandems. , We have also developed a unique semiconductor bonding strategy, termed smart stack. − Using well-organized Pd nanoparticle (NP) arrays as bonding mediators, series-connected two-terminal tandem cells consisting of III–V and c-Si subcells have been successfully fabricated with the best efficiency of 30.8% . To make the smart stack technique more attractive, however, it would be preferable to find alternative materials for costly Pd, whose price has recently been rising due to the increasing demand of many other industrial applications…”

Section: Introductionmentioning

confidence: 99%

Cu Nanoparticle Array-Mediated III–V/Si Integration: Application in Series-Connected Tandem Solar Cells

Mizuno

Makita

Mochizuki

et al. 2020

ACS Appl. Energy Mater.

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The integration of III−V materials with crystalline Si (c-Si) is a promising pathway to design high-performance optoelectronic devices, including solar cells. We have previously reported high-efficiency III−V/Si tandem cells using our unique semiconductor bonding technique, termed smart stack. In the conventional smart stack cells, Pd nanoparticle (NP) arrays have been commonly employed as bonding mediators between III−V and c-Si; however, from an economical point of view, the use of other low-cost metals would be preferable. Therefore, this study focused on the possibility of Cu. A polystyrene-block-poly-2-vinylpyridine (PS-b-P2VP)-based block copolymer was utilized to prepare Cu NP arrays. Desired Cu NP arrays were achieved by starting with self-assembled PS-b-P2VP micelles preloaded with Cu 2+ ions. Satisfying bonding properties (low-resistance interfaces) were confirmed when GaAs subcells were stacked on the Cu NP arrays formed on native-oxide-removed c-Si subcells. Conversion efficiencies of up to 25.9% have been demonstrated with triple-junction structures consisting of InGaP/GaAs top and c-Si bottom subcells. The long-term reliability of Cu NP array-mediated smart stack cells was also verified by the thermal cycle and damp heat tests. Hence, we have successfully confirmed that not only Pd but also Cu is available to realize high-efficiency smart stack cells.

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Section: Introductionmentioning

confidence: 99%

Cu Nanoparticle Array-Mediated III–V/Si Integration: Application in Series-Connected Tandem Solar Cells

Mizuno

Makita

Mochizuki

et al. 2020

ACS Appl. Energy Mater.

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“…The PV devices of double-junction GaAs (Device A and B, 0.26 cm 2 area) were fabricated by connecting two GaAs p–n junction subcells in series through a tunnel junction to allow their current–voltage characteristics so as to comply with the LSV data of the present electrolyzer (Figure A and Supporting Information). The double-junction GaAs PV structures were grown using molecular beam epitaxy. , The thicknesses of the upper and lower GaAs absorption layers were designed to increase J max by achieving the current matching conditions. The growth temperatures of double-junction GaAs PV devices were optimized to match up their current–voltage characteristics with the LSV data of the present electrolyzer.…”

Section: Resultsmentioning

confidence: 99%

“…The double-junction GaAs PV structures were grown using molecular beam epitaxy. 91,92 The thicknesses of the upper and lower GaAs absorption layers were designed to increase J max by achieving the current matching conditions. The growth temperatures of double-junction GaAs PV devices were optimized to match up their current−voltage characteristics with the LSV data of the present electrolyzer.…”

Section: ■ Introductionmentioning

confidence: 99%

Perfect Matching Factor between a Customized Double-Junction GaAs Photovoltaic Device and an Electrolyzer for Efficient Solar Water Splitting

Zahran

Miseki

Mohamed

et al. 2022

ACS Appl. Energy Mater.

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A photovoltaic (PV) device of double-junction GaAs/GaAs was customized to match up with the current density–voltage property of an efficient electrolyzer with a FeNiWO x /nickel foam (NF) anode and a Pt/NF cathode. The customization of the PV device resulted in a perfect matching factor (MF = 99%) in performances between the PV device and the electrolyzer for solar water splitting in a PV-electrolyzer (PVE) system. Efficient and stable (one-month) solar water splitting with a high solar-to-hydrogen efficiency (STH) of 13.9% was demonstrated under 1 sun irradiation conditions. The STH value is comparable with the top values (14.2–16%) in the state-of-art PVE systems. The high STH is based on an obvious progeny of the highest electricity-to-hydrogen efficiency (ETH = 85%) for the electrolyzers among the PVE systems with the non-precious metal-based anode in the electrolyzer and the perfect MF value (99%). This demonstrates that the perfect matching between the PV devices and the electrolyzers, as well as the development of the efficient electrolyzer successfully contribute to substantial improvement of STH and stability.

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“…These pinholes may act as shunt paths in the device, resulting in highlighted inconsistency with ITO/Ag contact (Figure e) that fully covers the top surface (where any pinholes in the film are contacted by the ITO, in contrast to the NiGeAu contacted cells, where the metallization covers only a fraction of the film surface). In future work, these issues can be mitigated using fully clean room processing and using more gentle bonding methods such as the “smart stack” process and Pd particle bonding. − …”

Section: Solar Cell Processingmentioning

confidence: 99%

Strain-Engineered Multilayer Epitaxial Lift-Off for Cost-Efficient III–V Photovoltaics and Optoelectronics

Haggrén

Tournet

Jagadish

et al. 2023

ACS Appl. Mater. Interfaces

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The efficient removal of epitaxially grown materials from their host substrate has a pivotal role in reducing the cost and material consumption of III−V solar cells and in making flexible thin-film devices. A multilayer epitaxial lift-off process is demonstrated that is scalable in both film size and in the number of released films. The process utilizes in-built, individually engineered epitaxial strain in each film to tailor the bending without the need for external layers to induce strain. Even without external support layers, the films retain good integrity after the liftoff, as evidenced by photoluminescence measurements. The films can be further processed into devices, demonstrated here with the fabrication of cm-scale solar cells using a three-layer lift-off process. Based on the included cost analysis, the solar cells are fabricated with a facile two-step process from the as-released films. The scalable multilayer lift-off process is highly cost-efficient and enables a 4-to-6-fold reduction in the cost with respect to the single-layer epitaxial lift-off process. The results are therefore significant for III− V photovoltaics and any other technologies that rely on thin-film III−V semiconductors.

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Dual-junction GaAs solar cells and their application to smart stacked III–V//Si multijunction solar cells

Cited by 14 publications

References 26 publications

Cu Nanoparticle Array-Mediated III–V/Si Integration: Application in Series-Connected Tandem Solar Cells

Cu Nanoparticle Array-Mediated III–V/Si Integration: Application in Series-Connected Tandem Solar Cells

Perfect Matching Factor between a Customized Double-Junction GaAs Photovoltaic Device and an Electrolyzer for Efficient Solar Water Splitting

Strain-Engineered Multilayer Epitaxial Lift-Off for Cost-Efficient III–V Photovoltaics and Optoelectronics

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