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Thin film solar cells need to meet some key requirements: |
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- Process-compatible and cheap substrate Þ large area deposition.
- Suitable direct band gap Þ high absorption coefficients f
- Insensitivity to "defects"
- Technology for junction and good ohmic contacts.
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Major contenders in (or close) to production are: |
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- Amorphous Si.
- Nanocrystalline thin film Si.
- Polycrystalline thin film Si.
- The CuInxGa1-xSe2 or "CIGS" family.
- The CdTe solar cell.
- May others in R&D
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The present "high potentials" are CdTe and CIGS. |
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High-efficiency multi-junction solar cells may find applications as "concentrator
cells" at the focus point of a large mirror or lens that tracks the sun. |
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CIGS and most other thin film solar cells have high internal resistances
and need to be switches in series after about 1 cm for high performance |
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This must be done automatically and in-situ as part of the production process. |
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A whole new technology needs to be developed for thin film solar cell mass production |
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The race between bulk Si solar cells and thin film technologies is open
in 2008; the winning technologies are to be determined. |
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© H. Föll (Semiconductor Technology - Script)
