Technique to increase solar cell efficiency by splitting solar light to multiple wavelength bands and directing each to optimized solar cells for that particular wavelength band.
The dominant application is concentrated photovoltaics.
Traditional solar cells with concentrating systems use expensive III-V or Ge substrates, require complicated film growth techniques for lattice matching and forming tunnel junctions, and necessitate current matching that is difficult to optimize for varying weather conditions.
This invention describes an integrated approach which splits the solar spectrum into different bands directed toward discrete solar cells with spectrally matched bandgaps. This allows cells to be optimized independently. For each discrete solar cell, a single crystalline thin film Ge cell can be grown on top of a Si substrate to be used as a virtual substrate, replacing the Ge substrate.
- Cost-savings compared to other spectrum splitting approaches
- CMOS compatible
- No longer a need for lattice and current matching
- Flexibility in material choice based on bandgap considerations
- Easy mounting
- Reduced optical loss compared to physically mounting individual cells on a common substrate