Assessing the operating temperature of multi-junction solar cells with novel rear side layer stack and local electrical contacts

Alonso-Álvarez, D.; Weiss, Charlotte; Fernandez, Jara; Janz, S.; Ekins-Daukes, N. J.

doi:10.1016/j.solmat.2019.110025

Cited by 10 publications

(6 citation statements)

References 13 publications

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“…The enhanced out-reflection up to 85% of photons in region II will decrease the cell temperature in operation. This decrease was published recently to be 9°C in a similar cell type as investigated in this article [8].…”

Section: Eqe and %R Measurement Of Isotypessupporting

confidence: 76%

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Passivated, Highly Reflecting, Laser Contacted Ge Rear Side for III-V Multi-Junction Solar Cells

Weiss

Schön

Höhn

et al. 2021

IEEE J. Photovoltaics

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This article describes the successful integration of a passivated, highly reflecting Ge rear side into a III-V multijunction solar cell. The use of lowly doped Ge and the new rear side leads to the aimed increase in Ge cell current up to 1.6 mA.cm −2 , demonstrated by external quantum efficiency and I-V measurements. For the contact formation, two different types of laser processes were conducted and evaluated-the laser fired contact route and the PassDop route. In both cases, the formation of a local back surface field preserves the passivation of the contact points. A laser pitch and laser power variation leads to a good performing back contact. The passivation effect is proven experimentally and is qualitatively accessed with cell simulations.

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Section: Eqe and %R Measurement Of Isotypessupporting

confidence: 76%

“…As a consequence, the cell temperature under operation is reduced and the voltage increased. It was shown recently that a rear side mirror similar to the one in this article leads to a temperature decrease in a space solar cell in operation of about 9 K [8].…”

Section: Introductionmentioning

confidence: 89%

Passivated, Highly Reflecting, Laser Contacted Ge Rear Side for III-V Multi-Junction Solar Cells

Weiss

Schön

Höhn

et al. 2021

IEEE J. Photovoltaics

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“…This passivation is similar to a passivation with SiN presented in [20]. It was shown recently that the SiC/Ag mirror on the backside leads to a decrease of 9 °C cell temperature under operation in space [21]. However, the use of the passivated germanium and rear-side mirror offers significantly higher advantages in four-junction solar cells, where the Ge bottom cell may limit the overall current of the device.…”

Section: Introduction Of Passivated Germaniummentioning

confidence: 76%

Development of Germanium-Based Wafer-Bonded Four-Junction Solar Cells

Höhn

Siefer

Janz

et al. 2019

IEEE J. Photovoltaics

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Multijunction solar cells with four junctions are expected to be the next-generation technology for both space and concentrator photovoltaic applications. Most commercial triplejunction solar cells are today grown on germanium, which also forms the bottom subcell. Extending this concept to four junctions with an additional ∼1-eV subcell was proven to be challenging. We investigate a new cell concept, which uses direct wafer bonding to combine a metamorphic GaInAs/Ge bottom tandem solar cell with a GaInP/AlGaAs top tandem on GaAs resulting in a monolithic four-junction cell on germanium. This article summarizes results of the cell developments, which have been resulting in a four-junction concentrator cell with 42% efficiency. We implemented a new passivated Ge backside technology to enhance the current generation in the Ge junction, and we propose realistic steps to realize solar cells with 45% efficiency using this cell architecture.

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“…Accordingly, the free carrier absorption has been almost halved, demonstrating that thinning the substrate is a valid solution to significantly decrease the heat generation caused by this type of absorption 7 . For instance, the use of lowly doped Ge substrates pursuing the same decrease in the free‐carrier absorption (FCA) has been reported to achieve temperatures 7–9°C cooler 27,28 . Assuming an average efficiency decrease with temperature of 0.9–1%/°C 29 for 3JSC, this could lead to an efficiency increase of about 6%–9% points.…”

Section: Resultsmentioning

confidence: 99%

Manufacturing process for III–V multijunction solar cells on germanium substrates with a total thickness below 60 microns

Lombardero

Cifuentes

Gabás

et al. 2022

Progress in Photovoltaics

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In this work, we demonstrate a new manufacturing process that allows to fabricate thin solar cells avoiding problems related to the brittleness or fragility of thin wafers without needing any carrier nor temporary substrate. This technique has been successfully applied to Ge single and GaInP/Ga(In)As/Ge triple-junction solar cells grown on Ge substrates, achieving 47.5-and 55.5-μm-thick substrates, respectively.Although this technique should allow to thin substrates to any desired thickness, a final thickness around 20-30 μm is recommended due to practical concerns such as the uneven substrate thickness throughout the wafer. In any case, a III-V solar cell with such a thickness should be thin enough for most applications and, in particular, for space ones.

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Assessing the operating temperature of multi-junction solar cells with novel rear side layer stack and local electrical contacts

Cited by 10 publications

References 13 publications

Passivated, Highly Reflecting, Laser Contacted Ge Rear Side for III-V Multi-Junction Solar Cells

Passivated, Highly Reflecting, Laser Contacted Ge Rear Side for III-V Multi-Junction Solar Cells

Development of Germanium-Based Wafer-Bonded Four-Junction Solar Cells

Manufacturing process for III–V multijunction solar cells on germanium substrates with a total thickness below 60 microns

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