Single junction GaAs - Ge stacked tandem cell

Effects of RF power on optical, electrical, and structural properties ofμc-Si1−xGex:H films was reported. Raman and FTIR spectra fromμc-Si1−xGex:H films reflected the variation in microstructure and bonding configuration. Unlike increasing the germane concentration for Ge incorporation, low RF power enhanced Ge incorporation efficiency inμc-Si1−xGex:H alloy. By decreasing RF power from 100 to 50 W at a fixed reactant gas ratio, the optical bandgap ofμc-Si1−xGex:H was reduced owing to the increase in Ge content from 11.2 to 23.8 at.%, while Ge-related defects and amorphous phase were increased. Consequently, photo conductivity of 1.62 × 10−5 S/cm was obtained for theμc-Si1−xGex:H film deposited at 60 W. By applying 0.9 μm thickμc-Si1−xGex:H absorber withXCof 48% and [Ge] of 16.4 at.% in the single-junction cell, efficiency of 6.18% was obtained. The long-wavelength response ofμc-Si1−xGex:H cell was significantly enhanced compared with theμc-Si:H cell. In the case of tandem cells, 0.24 μm a-Si:H/0.9 μmμc-Si1−xGex:H tandem cell exhibited a comparable spectral response as 0.24 μm a-Si:H/1.4 μmμc-Si:H tandem cell and achieved an efficiency of 9.44%.

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Modeling of AlGaAs on Si tandem PV cells for extended spectral conversion

MRS Proceedings ◽

10.1557/opl.2011.750 ◽

2011 ◽

Vol 1288 ◽

Author(s):

Mahieddine Emziane ◽

Alaeddine Mokri

Keyword(s):

Doping Level ◽

High Efficiency ◽

Primary Objective ◽

Design Constraints ◽

Single Junction ◽

Tandem Cell ◽

Optimum Configuration ◽

Double Junction ◽

Overall Efficiency ◽

Spectral Conversion

ABSTRACTThe primary objective of this modeling investigation is to optimize a two-junction three-terminal device under the AM1.5G spectrum. Based on previous studies, AlGaAs and Si cells, because of their energy bandgaps, can be combined together to achieve high-efficiency double-junction devices. In this study, the top cell is made of Al0.3Ga0.7As (1.817 eV) while the bottom cell is made of Si (1.124 eV). In order to avoid the losses and design constraints observed in two-terminal and four-terminal devices, the tandem cell AlGaAs/Si is designed with three-terminals. In order to determine the optimal structure of the device, the top and bottom junctions were investigated and optimized with regard to the thicknesses and doping level. The optimum configuration of the device shows an efficiency of 26.27% under the AM1.5G spectrum and one sun, which is higher than the efficiency of an optimized single-junction Si cell under the same illumination conditions. We also studied the effect of the optical concentration on the performance of the device and we found that the overall efficiency reaches over 31% under 50 suns.

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Photovoltaics: Upconversion Configurations versus Tandem Cells

MRS Advances ◽

10.1557/adv.2017.484 ◽

2017 ◽

Vol 2 (52) ◽

pp. 2997-3004 ◽

Cited By ~ 1

Author(s):

Joop van Deelen

Keyword(s):

Solar Cell ◽

Cost Reduction ◽

Solar Spectrum ◽

Maximum Efficiency ◽

Potential Contribution ◽

Single Junction ◽

Tandem Cell ◽

Wide Range ◽

A Cell ◽

Bandgap Tuning

ABSTRACTFor a wide range of bandgaps of solar cell materials, the potential contribution of upconversion materials was calculated and related to various configurations of the solar cell and upconversion layers. Moreover, by comparing these various strategies with the potential of a dual junction tandem cell configuration, a compelling case is made for upconverters.At idealized 100% conversion efficiency, the upconverter with a single junction cell is more efficient than a dual junction tandem cell. It was also found that a single junction cell with an upconverter that is ‘only’ 80% efficient has a similar efficiency as an ideal dual junction cell. This result shows that upconverters are certainly a route worthwhile to pursue, especially because the single junction cells plus upconverters could have more cost reduction potential than dual junction cell configurations.Additionally, it was investigated if an upconverter that uses two different photon energies would create a large surplus in efficiency. For a cell band gap of 1.55 eV a theoretical maximum efficiency (here defined as Voc*Isc) of 54.5% was calculated. Although there is a further increase in efficiency compared to converters with a single conversion energy, very careful bandgap tuning with a tolerance < 0.02 eV is required, which makes this system rather sensitive for material and solar spectrum fluctuations and it is suggested that a simple upconverter material is a more favorable strategy.

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High Quality Hot-wire Microcrystalline Silicon for Efficient Single and Multijunction N-i-p Solar Cells

MRS Proceedings ◽

10.1557/proc-0910-a26-03 ◽

2006 ◽

Vol 910 ◽

Cited By ~ 5

Author(s):

Robert L. Stolk ◽

Hongbo Li ◽

Ronald H. Franken ◽

Karine H.M. Van der Werf ◽

Jatindra K. Rath ◽

...

Keyword(s):

Solar Cells ◽

Spectral Composition ◽

Chemical Vapor ◽

Computer Code ◽

Hot Wire ◽

Microcrystalline Silicon ◽

Single Junction ◽

Tandem Cell ◽

Bottom Cell ◽

Current Limiting

AbstractIn this paper, the potential of hot-wire chemical vapor-deposited (HWCVD) microcrystalline silicon (μc-Si) for use in solar cells is explored. Incorporation of the material in the current-limiting bottom cell of two tandem cells on plain stainless steel resulted in FF values as high as 0.77, which is much higher than the highest single junction FF. A combination of experiments, calculations and computer simulations was employed to identify causes for the observed high tandem cell FF values. Both the light intensity and the spectral composition of the bottom cell illumination in a tandem were found to contribute to an increase of the bottom cell FF. The fact that the operational voltage of a tandem cell is higher than that of the current-limiting subcell, was calculated to lead to a tandem FF that can be far higher than that of the limiting cell. Com-puter simulations with the AMPS computer code show that the current mismatch in a tandem cell reduces the recombination in the current-limiting cell, possibly by slightly enhancing the internal field of that cell. Use of a 1.5 μm ìc-Si:H hot-wire deposited absorber layer in a single junction cell on a textured back reflector yielded a Voc, FF and Jsc of 0.543 V, 0.656 and 23.60 mA/cm2, respectively, which combine to an 8.4 % record efficiency for μc-Si single junction n-i-p cells with a hot-wire intrinsic layer.

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Modeling of Cascade Solar Cell Ga0.5In0.5P /GaAs Using AMPS-1D

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.685.174 ◽

2013 ◽

Vol 685 ◽

pp. 174-178

Author(s):

B. Dennai ◽

Hassane Ben Slimane ◽

A. Helmaoui

Keyword(s):

Solar Cell ◽

Tunnel Junction ◽

High Efficiency ◽

Primary Objective ◽

Band Gaps ◽

Design Constraints ◽

Single Junction ◽

Tandem Cell ◽

Optimum Configuration ◽

Double Junction

The primary objective of this modeling investigation is to optimize a multijunction cascade device under the AM1.5G spectrum. Based on previous studies, GaInP and GaAs cells between them tunnel junction GaAs, because of their energy band gaps, can be combined together to achieve high-efficiency double-junction devices. In this study, the top cell is made of Ga0.5In0.5P (1.74 eV) while the bottom cell is made of GaAs (1.42 eV). In order to avoid the losses and design constraints observed in two-terminal and four-terminal devices, the tandem cell GaInP /GaAs is designed with tunnel junction. In order to determine the optimal structure of the device, the top and bottom junctions were investigated and optimized with regard to the thicknesses. The optimum configuration of the device shows an efficiency of 36.4% under the AM1.5G spectrum and one sun, which is higher than the efficiency of an optimized single-junction Si cell under the same illumination conditions

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