Solar Cells

A forum designed mainly for high school physics students in New South Wales, Australia.
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Solar Cells

Post by Buwwy »


So solar cells consist of a n-type semiconductor joined together with a p-type, and the unbounded electrons from the n-type 'jump' to fill the holes on the p-type in the depletion zone (recombination process)

I was just wondering, for the solar cell to work, does the photon of energy have to strike the p-type or the n-type semiconductor? There's some sources saying that it is the n-type, and others saying the p-type. And my physics teacher says that it can strike either of them.

I would think that it is the p-type as the electric field created by the recombination process would have a greater effect on the electrons but I just need to make sure.

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Re: Solar Cells

Post by joe »

Photons in this example interact with electrons. So, if a photon in an n-type material is transferred to 'fill' a 'hole' in a p-type material, this electron has interacted with the photon that provided the energy for the process.

A proviso: Although photons share some properties of particles (e.g. quantisation, local interactions), they are not particles in the usual sense of the word. So, in general one has to be careful about talking about photons 'striking' electrons. However, in this case, momentum and energy are transferred from the photon to the electron (and to the lattice, in the case of the momentum), so it's not very misleading to say 'strike'.

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