Subcell I-V characteristic analysis of GaInP/GaInAs/Ge solar cells using electroluminescence measurements

Roensch, Sebastian; Hoheisel, R.; Dimroth, Frank; Bett, Andreas W.

doi:10.1063/1.3601472

Cited by 115 publications

(64 citation statements)

References 17 publications

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“…Two additional GaInAs detector arrays were used for the measurement of the low bandgap subcells. The procedure of determining the individual subcell voltages from the EL spectrum at different current densities follows the references [18,19].…”

Section: Methodsmentioning

confidence: 99%

Wafer bonded four‐junction GaInP/GaAs//GaInAsP/GaInAs concentrator solar cells with 44.7% efficiency

Dimroth

Grave

Beutel

et al. 2014

Progress in Photovoltaics

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536

301

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Triple-junction solar cells from III-V compound semiconductors have thus far delivered the highest solar-electric conversion efficiencies. Increasing the number of junctions generally offers the potential to reach even higher efficiencies, but material quality and the choice of bandgap energies turn out to be even more importance than the number of junctions. Several four-junction solar cell architectures with optimum bandgap combination are found for lattice-mismatched III-V semiconductors as high bandgap materials predominantly possess smaller lattice constant than low bandgap materials. Direct wafer bonding offers a new opportunity to combine such mismatched materials through a permanent, electrically conductive and optically transparent interface. In this work, a GaAs-based top tandem solar cell structure was bonded to an InP-based bottom tandem cell with a difference in lattice constant of 3.7%. The result is a GaInP/GaAs//GaInAsP/GaInAs four-junction solar cell with a new record efficiency of 44.7% at 297-times concentration of the AM1.5d (ASTM G173-03) spectrum. This work demonstrates a successful pathway for reaching highest conversion efficiencies with III-V multi-junction solar cells having four and in the future even more junctions.

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Section: Methodsmentioning

confidence: 99%

Wafer bonded four‐junction GaInP/GaAs//GaInAsP/GaInAs concentrator solar cells with 44.7% efficiency

Dimroth

Grave

Beutel

et al. 2014

Progress in Photovoltaics

Self Cite

536

301

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“…Because the voltage determined from EL is the actual junction voltage, this method is useful to remove the effects of series resistance at high currents and can also be used to determine the individual subcell voltages of multijunction solar cells. 11 We characterize the dark IV and g ext ðJ inj Þ here for a variety of GaInP solar cells to demonstrate the impacts of the optical and electronic structure on g ext ðJ inj Þ and thus the solar cell voltage.…”

mentioning

confidence: 99%

Enhanced external radiative efficiency for 20.8% efficient single-junction GaInP solar cells

Geisz

Steiner

García

et al. 2013

Applied Physics Letters

273

201

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We demonstrate 1.81 eV GaInP solar cells approaching the Shockley-Queisser limit with 20.8% solar conversion efficiency, 8% external radiative efficiency, and 80–90% internal radiative efficiency at one-sun AM1.5 global conditions. Optically enhanced voltage through photon recycling that improves light extraction was achieved using a back metal reflector. This optical enhancement was realized at one-sun currents when the non-radiative Sah-Noyce-Shockley junction recombination current was reduced by placing the junction at the back of the cell in a higher band gap AlGaInP layer. Electroluminescence and dark current-voltage measurements show the separate effects of optical management and non-radiative dark current reduction.

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“…6(a) and for an IMM with comparable band gaps. In conjunction with optical modeling, the EL measurement enables a determination of the dark currents of each junction [27] and the internal radiative efficiencies [1], [14], as shown in Fig. 7.…”

Section: Resultsmentioning

confidence: 99%

Optically Enhanced Photon Recycling in Mechanically Stacked Multijunction Solar Cells

Steiner

Geisz

Ward

et al. 2016

IEEE J. Photovoltaics

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Abstract-Multij unction solar cells can be fabricated by mechanically bonding together component cells that are grown separately. Here, we present four-junction four-terminal mechanical stacks composed of GalnP/GaAs tandems grown on GaAs substrates and GalnAsP/GalnAs tandems grown on InP substrates. The component cells were bonded together with a low-index transparent epoxy that acts as an angularly selective reflector to the GaAs bandedge luminescence, while simultaneously transmitting nearly all of the subbandgap light. As determined by electroluminescence measurements and optical modeling, the GaAs subceU demonstrates a higher internal radiative limit and, thus, higher subceU voltage, compared with GaAs subceUs without the epoxy reflector. The best cells demonstrate 38.8 ± 1.0% efficiency under the global spectrum at 1000 W/m 2 and ~ 42% under the direct spectrum at ~100 suns. Eliminating the series resistance is the key challenge for further improving the concentrator cells.

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Subcell I-V characteristic analysis of GaInP/GaInAs/Ge solar cells using electroluminescence measurements

Cited by 115 publications

References 17 publications

Wafer bonded four‐junction GaInP/GaAs//GaInAsP/GaInAs concentrator solar cells with 44.7% efficiency

Wafer bonded four‐junction GaInP/GaAs//GaInAsP/GaInAs concentrator solar cells with 44.7% efficiency

Enhanced external radiative efficiency for 20.8% efficient single-junction GaInP solar cells

Optically Enhanced Photon Recycling in Mechanically Stacked Multijunction Solar Cells

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