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Tandem solar cell

Thesis/Dissertation ·
OSTI ID:6819216
A model for the AlGaAs/GaAs heteroface with a low-high junction back surface field solar cell was developed, in which a closed form solution for the J-V characteristics of the cell is obtained using the integral form of the linear continuity equations. This model includes photogeneration currents in all regions, generation recombination currents in the depletion region, high level injection effects, and the effects of the low-high junction in the AlGaAs/GaAs and n-n/sup +/ GaAs interfaces. The AlGaAs/GaAs model was extended to the AlGaAsa/GaAsGe tandem solar cell model. Here, a AlGaAs/GaAs wide bandgap (1.42 eV) top cell, a Ge narrow bandgap (0.66 eV) bottom cell and a n/sup +/-p/sup +/ GaAs tunnel junction were combined. Alternate tandem cell structures without the AlGaAs window layer, and those with the tunnel junction half in the GaAs side and half in the Ge side, are also considered. A computer simulation predicted the device characteristics. The results are presented for a specific example, including J-V curves, fill factor, conversion efficiency and the effects of series and shunt resistances and temperature. Data presented in these examples show the relative importance of the components of tandem cells. Critical aspects of tandem solar cell fabrication were also explored. These included the use of organometallic epitaxy for fabricating GaAs solar cells and tunnel junctions.
Research Organization:
Rensselaer Polytechnic Inst., Troy, NY (USA)
OSTI ID:
6819216
Country of Publication:
United States
Language:
English