Projected performance of three- and four-junction devices using GaAs and GaInP

Kurtz, Sarah; Myers, D.; Olson, J. M.

doi:10.1109/pvsc.1997.654226

Cited by 113 publications

(74 citation statements)

References 8 publications

(2 reference statements)

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“…1,[7][8][9][10][11][12][13][14][15][16] As discussed below, the detailed balance approach yields a smaller J o , and, therefore, a higher efficiency than the ''standard'' solution to the one-dimensional problem. Theoretical efficiencies based on empirical data tend to reflect realistic, rather than ideal, efficiencies.…”

Section: Theoretical Modelsmentioning

confidence: 99%

A comparison of theoretical efficiencies of multi‐junction concentrator solar cells

Kurtz

Myers

McMahon

et al. 2008

Progress in Photovoltaics

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Champion concentrator cell efficiencies have surpassed 40% and now many are asking whether the efficiencies will surpass 50%. Theoretical efficiencies of >60% are described for many approaches, but there is often confusion about ''the'' theoretical efficiency for a specific structure. The detailed balance approach to calculating theoretical efficiency gives an upper bound that can be independent of material parameters and device design. Other models predict efficiencies that are closer to those that have been achieved. Changing reference spectra and the choice of concentration further complicate comparison of theoretical efficiencies. This paper provides a side-by-side comparison of theoretical efficiencies of multijunction solar cells calculated with the detailed balance approach and a common one-dimensional-transport model for different spectral and irradiance conditions. Also, historical experimental champion efficiencies are compared with the theoretical efficiencies. Copyright # 2008 John Wiley & Sons, Ltd. INTRODUCTIONAs the world's interest in renewable energy has increased, the investment in solar has also grown. New approaches to achieving high efficiencies have been proposed by numerous groups. Sometimes these new approaches are described as having a theoretical efficiency >60%. Will these new cells be superior to today's cells, which have now surpassed 40%? 1 Predicting the answer to this question requires two steps: (1) when comparing the theoretical efficiencies of existing and new approaches, the same methodology must be used for both, and (2) an assessment should be made of how close the experimental efficiency may, ultimately, approach the theoretical efficiency for each case. The first step is obvious, but is often neglected, resulting in comparison of numbers that were derived in different ways. When making such comparisons, the choice of the methodology is much less important than the consistency of the methodology. The second step is aided by a review of the efficiencies that have been achieved so far.Over the years, many studies have presented theoretical multi-junction solar cell efficiencies as a function of the materials' band gaps. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] In general, no two studies use exactly the same assumptions, resulting in a range of theoretical efficiencies. The efficiencies are especially dependent on the conditions (spectrum, concentration, and temperature). Concentrating the sunlight to the maximum value ($46 000 suns) results in theoretical efficiencies 10-20% (absolute) higher than the corresponding one-sun efficiencies. 4 Changing the spectrum has a smaller effect (typically 1-4% absolute). 17 The choice of the theoretical model, or assumptions used in the model, also affects the calculated efficiency. Marti et al. compared two of the most common models. 18 They defined a ''standard'' model using Shockley's diode equation, modeling a one-dimensional p-n junction with appropriate values for surface recombination, layer thicknesses, etc. They co...

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Section: Theoretical Modelsmentioning

confidence: 99%

A comparison of theoretical efficiencies of multi‐junction concentrator solar cells

Kurtz

Myers

McMahon

et al. 2008

Progress in Photovoltaics

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“…Incorporation of this material as a third junction under the currently successful GaInP/GaAs tandem cell has the potential to increase the calculated idealized AM1.5D conversion efficiency (at 500 suns) to more than 46 %, and more than 50 % with the incorporation of a junction in an underlying Ge substrate (3).…”

Section: Introductionmentioning

confidence: 99%

Optical investigation of GaNAs

Keyes

Geisz

Dippo

et al. 1999

AIP Conference Proceedings

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Abstract.A systematic study of the energy and time-resolved photolumienscence of GaInP/GaN x As 1-x double heterostructures has been performed for 0 x 1.3%. A large temperature-dependent optical-bowing coefficient (about 20-25 eV) is observed and the bandgap variation with temperature is found to depend on the nitrogen content. Finally, the minoritycarrier lifetime is not simply related to the nitrogen content. Instead, the recombination rate is proportional to the majority-carrier concentration for x 0.3% and the carbon concentration for x 0.3%.

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“…However, the Ge band gap is not optimal for the third junction: significantly higher efficiencies would be obtained if the third junction could be fabricated from a 1-eVband-gap material. If this next generation of multijunction devices could be achieved, the Ge junction could be reintroduced under this three-junction stack for a resulting monolithic, two-terminal device with projected real-world efficiencies above 35% for air-mass 0 (AM0) and above 40% for 500-suns terrestrial (3). This evolution of multijunction solar-cell structures from the existing two-junction device to futuregeneration three-and four-junction devices is shown in Figure 1, with projected idealized efficiencies for these devices.…”

Section: Introductionmentioning

confidence: 99%

New materials for future generations of III-V solar cells

Geisz¹,

Friedman²,

Olson³

et al. 1999

AIP Conference Proceedings

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Abstract. Three-and four-junction III-V devices are proposed for ultrahigh-efficiency solar cells using a new 1-eV material lattice-matched to GaAs, namely, GaInNAs. We demonstrate working prototypes of a GaInNAs-based solar cell lattice-matched to GaAs with photoresponse down to 1 eV. Under the AM1.5 direct spectrum with all the light higher in energy than the GaAs band gap filtered out, the prototypes grown with base doping of about 10 17 cm -3 have open-circuit voltages ranging from 0.35 to 0.44 V, short-circuit current densities of 1.8 mA/cm 2 , and fill factors from 61% to 66%. To improve on the current record-efficiency tandem GaInP/GaAs solar cell by adding a GaInNAs junction, the short-circuit current density of this 1-eV cell must be significantly increased. Because these low short-circuit current densities are due to short diffusion lengths, we have demonstrated a depletion-width-enhanced variation of one of the prototype devices that trades off decreased voltage for increased photocurrent, with a short-circuit current density of 7.4 mA/cm2 and an open-circuit voltage of 0.28 V.

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Projected performance of three- and four-junction devices using GaAs and GaInP

Cited by 113 publications

References 8 publications

A comparison of theoretical efficiencies of multi‐junction concentrator solar cells

A comparison of theoretical efficiencies of multi‐junction concentrator solar cells

Optical investigation of GaNAs

New materials for future generations of III-V solar cells

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