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Solar Cells (1 Viewer)

itsalberttrinh

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Solar cells consists of a p-type and n-type semiconductor joined together. The free electrons in the n-type will diffuse across the p-n junction to fill the holes in the p-type semiconductor. This causes the n-type to become more positive and the p-type to become more negative setting up an initial potential difference. This sets up an electric field across the p-n junction which prevents further electrons diffusing across the p-n junction, this is known as the depletion zone. Thus when light above the threshold frequency strikes the surface of the solar cell, electrons will be liberated due to the photoelectric effect and will pass through the external circuit as opposed to the p-n junction and thus forming an electric current.

These are usually 4 markers if anyone else could tell me what I am missing, it would be highly appreciated :)
 
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Just remember this flow chart/list

1. P type and n type silicon are placed together. This forms a p-n junction at their point of contact.

2. at this p-n junction forms a depletion layer where the free electrons from the n side diffuse into the positive holes on the p side.

3. Since there are no mobile charge carriers and the n side is more positive and the p side is more negative an electric field forms. The direction of this electric field is from the n side to the p side.

4. Photon of light strikes this p-n junction.

5. Electron is ejected (Photoelectric effect) in this p-n junction. ALWAYS STATE RELEVANT LAWS OF PHYSICS.

6. A free electron and positive hole is formed. The free electron in the electric field is accelerated to the outer boundaries of the n side due to ELECTROSTATIC force (F=Eq). The positive hole is accelerated to the outer boundaries of the p side.

7. Now there is a potential difference on the opposite ends of the solar cell. It is like a battery.

8. When it is connected to an external circuit a CONVENTIONAL current flows from the p side to the n side.
 

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