Why can't an a-Si:H solar cell rely on diffusion to separate the photogenerated carriers as much as a c-Si solar cell does?
A. The higher bandgap (around 1.7 eV) prevents the photogenerated carriers from diffusing through the intrinsic layer of the a-Si:H cell.
Because the absorption coefficient of a-Si:H is 70 times higher than that of c-Si in the visible region of the solar spectrum.
C. Because the diffusion length is around 300 nm, while in c-Si it is around 300 microns.
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In the figure below the bandgap versus the lattice constant of various materials is shown.Which of the following statements is true?
A. The junctions of a lattice-matched triple junction solar cell can be based on the semiconductor materials GaInP, GaAs and Si.
B. If the bottom cell of a 4-junction cell is based on Ge, the first junction above the bottom cell is based on GaInAs.
C. A combination of three junctions based on the semiconductor materials GaInP, GaAs and Ge can only result in a metamorphic triple junction solar cell.
D. The semiconductor material InAs is a logic choice to be used as a top cell in a triple junction.
The figure below shows the I-V curves of two single junction solar cells. If you were to make a multi-junction solar cell with these two cells, which one will you put as a top cell?
A. Cell #1.
B. Cell #2.
Looking at this band diagram of a semiconductor material, can this material be used as a photoanode or as a photocathode?
A. Photoanode
B. Photocathode
C. It could be used as both
Which of the effects listed below are considered to be main limiting factors for increasing the current density of the photoelectrodes?Note that more than one correct answer is possible.
A. Band gap of the semiconductor forming the photoelectrode
B. Reflection in the electrolyte between the light source and the photoelectrode
C. Separation of charges in the photoelectrode semiconductor material
D. Catalytic effects in the photoelectrode surface
E. Mass transport of the ion within the electrolyte
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