State the basic process involved in the generation of emf in a solar cell when light falls on it
Answers
Solar cell
Principle–These photo voltaic devices convert the optical radiation into electricity
Circuit
When solar light falls on a p-n junction, it generates emf
As the solar radiation is incident at the junction, the junction area is kept much larger for more power generation
A p Si layer of about 300 * 10-6m is taken. About this a still thin layer of about 0.3 * 10-6 m n Si layer is grown on one side by the process of diffusion
The other side of the p-layer is coated with a metal. This servers as a back contact
On the top of n Si layer, metallic grid is deposited. This is called front contact
The light is incident on the grid from the top
Working
The generation of emf by the solar cell, when light falls on, is due to the following three basic processes – (a) generation (b) separation and (c) collection
Generation
The generation of electron-hole paid due to light with energy hט> Eg close to the junction
Separation
The separation of electrons and holes due to the electric field of the depletion region
The electrons are swept to the n-side and the holes to the p-side
Collection
The electrons reaching the n-side are collected by the front contact and holes reaching the p-side are collected by the back contact
Thus, the p-side becomes positive and the n-side becomes negative giving rise to photo voltage
When external load is connected, a photo current IL flows through the load
Graph
The graph showing the VI characteristics, with V along the X-axis and I along the Y-axis is as given above
The graph is indicated in the fourth quadrant as solar cell does not draw current but supplies the same to the load
Application
Solar cells are used in power electronic devices in satellites and space vehicles
They are also used as power supply in calculators
Criteria for material selection of material for solar cell
Band gap between 1.0 and 1.8 eV
High optical absorption
Electrical conductivity
Availability of raw material
Cost effective
Basic process involved in the generation of emf in a solar cell:
- The basic or commonly known fact about solar cell is that falling of energy by photons on circuit and conversion into electrical signals.
- But the main process between these two things are due to the diode that is present here.
- Generation of electrons and holes happen or occurs due to falling of solar energy.
- Then come the path of separation where the two electron hole pair are separated to 'N' region and 'P' region by application of electric field.
- The final process collection happens when the load is connected to the positive and negative points created due to sweeping of electrons "2n" and holes to 'P' region.
To know more:
Explain briefly the three process due to which generation of emf takes place in a solar cell
https://brainly.in/question/8714683