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Option 1 : Si
The correct answer is Si.
- The element used in making solar cells is silicon.
- Solar cells contain a p-n junction diode which is usually made of Si and GaAs.
- The device used to convert solar energy into electrical energy is known as solar cells.
- It is based on photovoltaic effects.
- The photoelectric effect is defined as the generation of voltage due to the bombardment of light photons.
- Pure silicon which is crystalline in nature is a poor conductor of electricity as it is a semiconductor material at its core.
- Working Principle of Solar cells.
- Works on the principle of photovoltaic effect.
- When light falls on the solar panel, the light photons reach the silicon junction.
- They excite electrons from the valence band to the conduction band, leaving behind an equal number of holes in the valence band.
- These electron –holes pairs generated in the depletion region move in opposite directions due to the barrier field.
- Photo-generated electrons move towards the n side and holes towards the p side.
- The collection of these charge carriers makes the p-side a positive electrode and the n side a negative electrode.
- Hence a photovoltage is set up across the junction.
- Advantages of solar cells are:
- Pollution free.
- Long-lasting.
- Maintenance free.
- Can be used anywhere as a self-generating source of electricity.
- Disadvantages:
- High cost of installation.
- Low efficiency.
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