Construction and working of solar cell
What is solar cell?
The solar cell are made from semiconducting material like silicon. Most of the commercial available solar cell are made from a highly pure single crystal of silicon with minute amount of trace element like boron and phosphorus.
Construction of solar cell:-
Here thin layer of p type material is dopped on thin layer of subset to form PN junction.
The thickness of p layer is very small. Electrical context are made to the diffused reason as well as to the base of silicon wafer.
To enhance the transmission of light into the material and anti reflecting coating is given to the p type layer.
Working of solar cell:-
When the incident sunlight fall on the upper p-region through silicon wafer the electron-hole pair is generated.
The thickness of p-region is very small. hence the electron and whole immediately reached to the junction therefore the probability of recombination is much reduced.
At the junction they face barrier potential which separate them. The barrier potential swipes electron from the p-region to N-region and number of holes from N-region to p-region this leads to an increase the number of holes in P-region and number of electron in N-side of the junction.
Such accumulation of charges on two side of junction produces a voltage or EMF known as photo EMF.
It is known as open circuit voltage and its proportional to the elimination as well as size of eliminating area. When an external circuit is connected across solar cell terminal the current flows in the circuit the solar cell behaves as a solar battery with n side negative terminal and p side positive terminal.
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