Thorough subcells diagnosis in a multi-junction solar cell via absolute electroluminescence-efficiency measurements

Chen, Shaoqiang; Zhu, Lin; Yoshita, Masahiro; Mochizuki, Takayasu; Kim, Changsu; Akiyama, Hidefumi; Imaizumi, Mitsuru; Kanemitsu, Yoshihiko

doi:10.1038/srep07836

Cited by 82 publications

(58 citation statements)

References 34 publications

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“…Absolute electroluminescence measurements have shown potential to gauge the material quality by deducing the internal radiative efficiency. 1 In this technique, the internal radiative efficiency can be extracted using a generalized optoelectronic model of multijunction solar cells. 2 However, careful calibration of the optical setup is required to achieve high accuracy in determining the absolute photon emission, i.e., the external radiative efficiency.…”

Section: Introductionmentioning

confidence: 99%

Nonradiative lifetime extraction using power-dependent relative photoluminescence of III-V semiconductor double-heterostructures

Walker

Heckelmann

Karcher

et al. 2016

Journal of Applied Physics

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A power-dependent relative photoluminescence measurement method is developed for double-heterostructures composed of III-V semiconductors. Analyzing the data yields insight into the radiative efficiency of the absorbing layer as a function of laser intensity. Four GaAs samples of different thicknesses are characterized, and the measured data are corrected for dependencies of carrier concentration and photon recycling. This correction procedure is described and discussed in detail in order to determine the material's Shockley-Read-Hall lifetime as a function of excitation intensity. The procedure assumes 100% internal radiative efficiency under the highest injection conditions, and we show this leads to less than 0.5% uncertainty. The resulting GaAs material demonstrates a 5.7 ± 0.5 ns nonradiative lifetime across all samples of similar doping (2–3 × 1017 cm−3) for an injected excess carrier concentration below 4 × 1012 cm−3. This increases considerably up to longer than 1 μs under high injection levels due to a trap saturation effect. The method is also shown to give insight into bulk and interface recombination.

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Section: Introductionmentioning

confidence: 99%

Nonradiative lifetime extraction using power-dependent relative photoluminescence of III-V semiconductor double-heterostructures

Walker

Heckelmann

Karcher

et al. 2016

Journal of Applied Physics

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“…We also developed a secondary standard for absolute EL calibrations to solidify the accuracy of absolute EL measurements. We indeed applied this method to InGaP/GaAs/Ge lattice-matched 3-junction tandem solar cells for satellite use [17,18].…”

Section: Invited Papermentioning

confidence: 99%

“…By introducing absolute flux calibrations, this method was extended to absolute EL measurements [16][17][18], and used to evaluate radiative recombination efficiencies ( and ) [16], and to evaluate all the loss terms in subcells in multi-junction solar cells under arbitrary illumination and bias conditions without adjusting any parameter [17,18]. Via absolute EL measurement under the dark condition, we are able to determine and analyze the balance sheets of energy and carriers in the subcells and the total cell, as well as subcell IV characteristics, and .…”

Section: Invited Papermentioning

confidence: 99%

Multi-junction-solar-cell designs and characterizations based on detailed-balance principle and luminescence yields

et al. 2015

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We developed a straightforward method based on detailed balance relations to analyze individual subcells in multijunction solar cells via measuring absolute electroluminescence quantum yields. This method was applied to characterization of a InGaP/GaAs/Ge 3-junction solar cell for satellite use. In addition to subcell I-V characteristics and internal luminescence yields, we derived balance sheets of energy and carriers, which revealed respective subcell contributions of radiative and nonradiative recombination losses, junction loss, and luminescence coupling. These results provide important diagnosis and feedback to fabrications. We calculated conversion-efficiency limit and optimized bandgap energy in 2-, 3-, and 4-junction tandem solar cells, including finite values of sub-cell internal luminescence quantum yields to account for realistic material qualities in sub-cells. With reference to the measured internal luminescence quantum yields, the theoretical results provide realistic targets of efficiency limits and improved design principles of practical tandem solar cells.

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“…Since external luminescence efficiencies depend on sample geometry, the internal luminescence efficiency is more useful when characterizing a solar cell for possible performance improvement9. They are usually determined using electroluminescence (EL) techniques1011121314. Since it is difficult to find the suited conditions for measurement, a simpler optical measurement would be favourable.…”

mentioning

confidence: 99%

Internal luminescence efficiencies in InGaP/GaAs/Ge triple-junction solar cells evaluated from photoluminescence through optical coupling between subcells

Tex

Imaizumi

Akiyama

et al. 2016

Sci Rep

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In-situ characterization is one of the most powerful techniques to improve material quality and device performance. Especially in view of highly efficient tandem solar cells this is an important issue for improving the cost-performance ratio. Optical techniques are suitable characterization methods, since they are non-destructing and contactless. In this work, we measured the power dependence of photoluminescence (PL) from the InGaP and GaAs subcells of an industry-standard triple-junction solar cell. High luminescence yields enhance the luminescence coupling, which was directly verified by time-resolved PL measurements. We present a new method to determine the internal luminescence efficiencies of InGaP and GaAs subcells with the aid of luminescence coupling. High luminescence efficiencies of 90% for GaAs and more than 20% for InGaP were found, which suggest that the material quality of the grown GaAs layer is excellent while the intrinsic luminescence limit of InGaP is still not reached even for high excitation conditions. The PL method is useful for probing the intrinsic material properties of the subcells in flat band condition, without influence of transport. Since no calibration of absolute PL is required, a fast screening of the material quality is possible, which should be extremely helpful for the solar cell industry.

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Thorough subcells diagnosis in a multi-junction solar cell via absolute electroluminescence-efficiency measurements

Cited by 82 publications

References 34 publications

Nonradiative lifetime extraction using power-dependent relative photoluminescence of III-V semiconductor double-heterostructures

Nonradiative lifetime extraction using power-dependent relative photoluminescence of III-V semiconductor double-heterostructures

Multi-junction-solar-cell designs and characterizations based on detailed-balance principle and luminescence yields

Internal luminescence efficiencies in InGaP/GaAs/Ge triple-junction solar cells evaluated from photoluminescence through optical coupling between subcells

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