How does a Solar Cell Work? (1 Viewer)

[freeeeee]

Farr out most confusing DP ever, poorly explained by my Jac textbook sigh...

My Understanding:
1. When a photon of sufficient energy is absorbed by an electron in the junction region it creates a photoelectron and
hole. 2. The extra electrons in the lattice of the n-type semiconductors at the boundary move to fill holes present in the lattice of the p-type semiconductor. This establishes an electric field which directs the photoelectrons produced towards the n-type semiconductor to accumulate, the holes drift in the opposite direction into the p-type layer creating a potential difference between the two layers.
3. Therefore connection of the solar cell to an external circuit will allow current to flow through the load as the potential difference causes electrons to travel from the n-type via the external circuit to arrive at holes in the p-type

Please correct me if i am wrong =) TY

 

[Bosanski Heroj]

If you want a better explanation, use this website http://hsc.csu.edu.au/physics/core/implementation/

 

[freeeeee]

If you want a better explanation, use this website http://hsc.csu.edu.au/physics/core/implementation/

I read that site already, not really that helpful especially if the question is 3+ worth in marks, since that explanantion really doesn't go into detail

 

[eshay lad 69]

check out this thread it has a pretty good description

http://community.boredofstudies.org/showthread.php?t=291080

 

[freeeeee]

eshay why did u link me back to my original post ??

 

[freeeeee]

bump anyone can help me?

 

[asianese]

That's not quite right...

Number 2 should come first. This is before any light hits. It is quite important when explaining solar cells.

 

[freeeeee]

That's not quite right...

Number 2 should come first. This is before any light hits. It is quite important when explaining solar cells.

so is everything right but not the order?

 

[Fizzy_Cyst]

As Asianese said, mention the diffusion and E-field first

- Solar cell converts solar energy --> electrical energy
- N-type is thin and transparent (top layer) so that photons of sunlight can travel through N-type and hit the junction
- P/N junction and subsequent diffusion of majority charge carriers
- Set up of electric field and establishment of Depletion region (this ensures junction acts as a diode -- current can only flow one way (Really important and explains why Solar Cells produce DC, not AC)
- Light of appropriate frequency hits junction, creates electron-hole pairs
- Electrons and holes can only travel one way (electrons from P --> N and Holes N --> P due to electric field)
- Electrons travel through external circuit, do work on a load (light globe for example) and then recombine with a hole as they re-enter the P-type SC.


Make sure you are able to draw a quick diagram of a Solar Cell, diagrams always aid in explaining complicated concepts, even if the question doesnt necessarily ask for a diagram they are generally included in the higher-level responses from the higher-level students.

 

[freeeeee]

great explanation ^ TY!!

 

[freeeeee]

As Asianese said, mention the diffusion and E-field first

- Solar cell converts solar energy --> electrical energy
- N-type is thin and transparent (top layer) so that photons of sunlight can travel through N-type and hit the junction
- P/N junction and subsequent diffusion of majority charge carriers
- Set up of electric field and establishment of Depletion region (this ensures junction acts as a diode -- current can only flow one way (Really important and explains why Solar Cells produce DC, not AC)
- Light of appropriate frequency hits junction, creates electron-hole pairs
- Electrons and holes can only travel one way (electrons from P --> N and Holes N --> P due to electric field)
- Electrons travel through external circuit, do work on a load (light globe for example) and then recombine with a hole as they re-enter the P-type SC.


Make sure you are able to draw a quick diagram of a Solar Cell, diagrams always aid in explaining complicated concepts, even if the question doesnt necessarily ask for a diagram they are generally included in the higher-level responses from the higher-level students.

Hey i got a question how come in the 2004 HSC Q25 it says the p-type layer is the top layer and it is thin and transparent? I got confused again haha, The Jacaranda textbook agrees with you though, says n-type layer is exposed to light.

Can you explain it to me? TY =D

 

[someth1ng]

Fizzy_Cyst does it right, I would further emphasise the need to include a diagram. You can't do well without a proper diagram since it won't make proper sense.

 

[freeeeee]

Question:is this right?
Due to subsequent diffusion of the majority of charge carriers, a depletion zone establishes which acts as an insulator preventing the movement of electrons across the boundary. Therefore when light liberates electrons from the junction the photoelectron must travel through the external circuit

 

[someth1ng]

Question:is this right?
Due to subsequent diffusion of the majority of charge carriers, a depletion zone establishes which acts as an insulator preventing the movement of electrons across the boundary. Therefore when light liberates electrons from the junction the photoelectron must travel through the external circuit

That's not quite the reason, it's the electric field that is produced by the depletion zone which allows only positive charge or in this case, holes, to pass through the depletion zone but the electric field disallows negative charge to pass through the depletion zone.

 

[freeeeee]

great thanks for the clarification =D