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Question
Describe the working principle of a solar cell. Mention three basic processes involved in the generation of emf.
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Solution
Solar cell is a p-n junction device which works on the principle of conversion of solar energy into electrical energy by generating emf. The generation of emf by a solar cell when light falls on it is due to following three processes:
- The upper layer of p-type semiconductor is made very thin so that the incident light photons may easily reach the p-n junction.
- When the photon of light of energy greater than forbidden energy gap (
\[h\nu > E_g\]is incident on a p-n junction, electron-hole pairs are generated in the depletion layer.
- The photo-generated electrons reaching the n-side of p-n junction . The photo generated holes reaching the p-side are of p-n junction. Thus, the p-side becomes positively charged and the n-side becomes negatively charged, giving rise to photovoltage.
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