Question

Describe the working principle of a solar cell. Mention three basic processes involved in the generation of emf.

Answer 1

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.