Question
- Describe the working principle of a solar cell. Mention three basic processes involved in the generation of emf.
- Why are Si and GaAs preferred materials for solar cells?
✓
Answer
- When solar cell is illuminated with light photons of energy $(hv)$ greater than the energy gap $\text{E}_{\text{g}}$ of the semiconductor, then electron hole pairs are generated due to absorption of photons.
The three basic processes involved in the generation of emf:
- Generation of e-h pairs due to light with close to the junction.
- Separation of electrons and holes due to electric field of the depletion region.
- The electrons reaching the n side are collected by the front contact and holes reaching p side are collected by back contact.
- Solar radiation has maximum intensity of photons of energy = 1.5eV.
Hence semiconducting materials Si and GaAs, with band gap $\approx$ 1.5 eV, are preferred materials for solar cells.
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