20%-efficient epitaxial GaAsP/Si tandem solar cells

Fan, Shizhao; Yu, Zhengshan J.; Sun, Yukun; Weigand, William A.; Dhingra, Pankul; Kim, Mi‐Jung; Hool, Ryan D.; Ratta, Erik D.; Holman, Zachary C.; Lee, Minjoo Larry

doi:10.1016/j.solmat.2019.110144

Cited by 38 publications

(20 citation 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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“…Direct epitaxial growth in contrast enables a simplified fabrication route as the III–V subcells are deposited onto the Si bottom cell by epitaxial methods such as metalorganic vapor‐phase epitaxy (MOVPE) [ 6,7 ] or molecular beam epitaxy (MBE). [ 8 ] In 2020, an epitaxial GaAsP/Si dual‐junction solar cell with a verified AM1.5g conversion efficiency of 23.4% has been presented by Lepkowski et al [ 9 ] Fan et al presented a similar GaAsP/Si design with an in‐house measured (uncertified) efficiency of 25.0%. [ 10 ] Both results show the intense research leading to a strong efficiency increase over the last years.…”

Section: Introductionmentioning

confidence: 99%

Epitaxial GaInP/GaAs/Si Triple‐Junction Solar Cell with 25.9% AM1.5g Efficiency Enabled by Transparent Metamorphic Al_xGa_1−xAs_yP_1−y Step‐Graded Buffer Structures

et al. 2021

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III–V/Si multi‐junction solar cells are potential successors to the silicon single‐junction cell due to their efficiency potential of up to 40% in the radiative limit.[1] Herein, latest results of epitaxially integrated GaInP/GaAs/Si triple‐junction cells are presented. To reduce parasitic absorption losses, which have limited the current density in the Si bottom cell in the previous devices, transparent AlxGa1–xAsyP1–y step‐graded metamorphic buffers are investigated. Compared with previous GaAsyP1–y step‐graded buffers, the transmittance is enhanced significantly, while no significant impact on the threading dislocation density is observed. Implemented into a new triple‐junction solar cell, an increase in short‐circuit current density from 10.0 to 12.2 mA cm−2 is achieved, leading to a new record conversion efficiency of 25.9% under AM1.5g conditions.

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“…Moreover, as a bottom-cell in monolithic tandems, SHJ cells only absorb in the infrared range, so the parasitic absorption in the near UV range of amorphous silicon layers (a-Si:H) do not generate short-circuit current losses. Such tandem solar cells with SHJ bottom-cell demonstrated efficiency of 20% with GaAsP top-cell [5] and efficiencies up to 29.15% with perovskite based top-cell [6]. To obtain a good monolithic tandem, the junction between the two sub-cells is a key feature.…”

Section: Introductionmentioning

confidence: 99%

Microcrystalline Silicon Tunnel Junction for Monolithic Tandem Solar Cells Using Silicon Heterojunction Technology

Puaud

Ozanne

Senaud

et al. 2021

IEEE J. Photovoltaics

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In this study, we developed a microcrystalline silicon tunnel junction to be used as a tunnel recombination junction between a large-gap top-cell and a silicon heterojunction bottomcell, in a monolithic tandem integration. This junction is composed of a p-type layer on the top of an n-type layer, deposited by plasma-enhanced chemical vapor deposition at low temperature (200°C). Microcrystalline phase percentage was controlled with Raman spectroscopy and ellipsometry measurements. The total stack has a thickness of 40 nm and an average conductivity around 10 S/cm. Minority carrier lifetime measurements showed an improvement of the field effect and the passivation with the addition of this junction on top of silicon heterojunction solar cells. Moreover, implementation of microcrystalline layer on top of reference rear emitter silicon heterojunction solar cells improved the fill factor and did not induce parasitic absorption above 700 nm. Simple tests structures were fabricated in order to characterize the tunnel junction and optimize it. Then, we carried out dark temperature-dependent I-V measurements on those test structures and observed peaks and valleys, characteristic of the junction tunnel behavior. The developed tunnel junction shows low contact resistivity and activation energies these are promising results for the complete integration on the tandem device.

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20%-efficient epitaxial GaAsP/Si tandem solar cells

Cited by 38 publications

References 50 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

Epitaxial GaInP/GaAs/Si Triple‐Junction Solar Cell with 25.9% AM1.5g Efficiency Enabled by Transparent Metamorphic Al_xGa_1−xAs_yP_1−y Step‐Graded Buffer Structures

Microcrystalline Silicon Tunnel Junction for Monolithic Tandem Solar Cells Using Silicon Heterojunction Technology

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20%-efficient epitaxial GaAsP/Si tandem solar cells

Cited by 38 publications

References 50 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

Epitaxial GaInP/GaAs/Si Triple‐Junction Solar Cell with 25.9% AM1.5g Efficiency Enabled by Transparent Metamorphic AlxGa1−xAsyP1−y Step‐Graded Buffer Structures

Microcrystalline Silicon Tunnel Junction for Monolithic Tandem Solar Cells Using Silicon Heterojunction Technology

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Product

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Epitaxial GaInP/GaAs/Si Triple‐Junction Solar Cell with 25.9% AM1.5g Efficiency Enabled by Transparent Metamorphic Al_xGa_1−xAs_yP_1−y Step‐Graded Buffer Structures