fabrication of solar cell

The first practical photovoltaic cell was developed in 1954 at Bell Laboratories .They used a diffused silicon p–n junction that reached 6% efficiency, compared to the selenium cells in fabrication of solar cell.

fabrication of solar cell

Most practical solar cells are silicon based ,because it is cheap and abundant material.

STEPS of fabrication of solar cell

  • First step is refining silicon
  • Silicon dioxide (SiO2) is the most abundant mineral in the earth’s crust.
  • The manufacture of the hyper pure silicon for photovoltaics starts with locating a source of silicon dioxide in the form of sand.
  • The silica is reduced (oxygen removed) through a reaction with carbon in the form of coal, charcoal and heating to 1500-2000 °C in an electrode arc furnace.
  • Silicon di oxide + Carbon = Silicon + Carbon di oxide
  • The resulting silicon is 98% pure. It contains Fe, Al, and B , to remove these traces , further purification is done ,Powdered Si is reacted with anhydrous HCl at 300 C to form SiHCl3
  • During this reaction impurities such as Fe, Al, and B react to form their halides (e.g. FeCl3, AlCl3, and BCl3).
  • The SiHCl3 has a low boiling point of 31.8 C and distillation is used to purify the SiHCl3 from the impurity halides.
  • Finally, the pure SiHCl3 is reacted with hydrogen at 1100 C for ~200 – 300 hours to produce a very pure form of silicon.
  • Above reaction takes place inside large vacuum chambers and the silicon is deposited onto thin polysilicon rods (small grain size silicon) to produce high-purity polysilicon rods of diameter 150-200mm.
  • Silicon used for solar cells can be single crystalline, multi crystalline, polycrystalline or amorphous. The key difference between these materials is degree to which the semiconductor has a regular, perfectly ordered crystal structure.
  • AFTER GETTING THE REQUIRED SILICON FROM ABOVE MENTIONED CHEMICAL PROCEDURE , different methods of solar cells fabrication are applied , each method involves doping of silicon to make p-n junction , and required processes to make a furnished solar cell.

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