I hope I can add to this discussion too :)

A Solar Cell is composed by a p-type and a n-type semiconductor materials placed together in physical contact.

So, a tiny region of very small thickness (could be up to 1 um, depending on the level of concentration of dopants) is created between the juntion of the p-type and the n-type materials (called a pn juction).

This region is called the Depletion region or the Space Charge (depleted) región. since the atoms of one side of this region are depleted of electrons (they end positively charged) and on the other side of the region the atoms end depleted of holes (they end negatively charged), so there is negative ions on one side and positive ions on the other, resulting in an induced Electric Field.

so, if you drop an electric charged particle within this region, the particle will move from one side of the pn union to the other.

Then you have your solar cell connected to an electric load, closing the circuit (meaning that if you have any current in the circuit, the electric charges in this current will flow throught the circuit.

Then, what happens when the solar cell operates under the sunlight is the following:

the photons which comes from the sun in the form of sunlight , can be viewed as an individual particles carrying a certain amount of linear momentum: (p=h/lamda). If these photons happen to carry a larger amount of energy than the energy needed to "promote" an electron from the valance band to the conduction band (the latter means: to provide the neccesary energy to an electron to get from the valance band (the energy band where the electrons are slightly tighted to its atoms) to the conduction band (the energy band where the electrons and more like delocalized in a less potential energy band (not so tighted to its atoms))

This amount of energy (the energy which must be carried by the photon) is equals or greater than the Energy Band gap of the semiconductor.

in this case we are interesting in having a not so large energy's band gap semiconductor material, so the light can generate electrons of conduction on the upper layer of the solar cell (we call this layer "the window layer", which it happens to be the n-type semiconductor of the solar cell structure, in almost the majority of the cases anyways).

So the photons enter from the upper side of the structure, and excite (detach from its valance atomic layer from the atom which it was linked) an electon (as explained above). This process is called an Electron-hole Pair Generation, since this electron is gonna continue linked (energetically linked, they are associated still (the lectron and the hole)) to the hole left by it, on its atomic valance band (this entity: the electron-hole pair is called an Exciton)

The concept of exciton then is useful to understand the last part of the process:

Then the Exciton travels on the direction of the pn juction (remember the process started on the n-type side) (electron and hole separated but energetically linked).

the Exciton reach the Depletion layer where the Electric Field has been established. , the Electric Field separates the electron from the hole, and since an electric load is connected to the circuit and the circuit is closed, there is a polarization on the circuit (i.e. at the both sides of the pn structure (or solar cell structure)).

So you will have an electron's current flowing to one side of the circuit and a hole's current flowing to the opposite side.

I hope it can bu useful !

Best Regards ! :)

Hi Dear,

In solar cells when sunlight shines on the surface on n-type semiconductor in a p-n junction, photons transmit the corresponding energy to its collision partner, electron and hence electron moves from n-type to p-type thus hole generates on n-region i.e depletion region is formed. Now when you apply potential greater than the depletion barrier potential, electron will migrate throughout the cell thereby generating electricity.

This is the most simple and crude explanation of solar cell.

You can refer to some popular books for details....

Thanks

Thanks Archisman Dutta.

Solar cell works on three basic phenomena, 1) Photon/light absorption and charge generation, 2) charge separation, and 3) charge collection. Thus, it requires 1) absorbing material, semiconductor, 2) p-n junction, and 3) contacts for electron and hole collection. In a p-n junction, depletion layer is creased due to flow of electron from n-region to p-region, and hole in opposite direction. Thus, a potential is developed. When the solar cell is illuminated with light, the photons are absorbed in n-region, depletion region, and p-region. Due to built-in potential of p-n junction, the minority carries (electron in p-region moves towards n-region, hole in n-region moves towards p-region) are separated. These minority charge carries are collected by metallic contacts.

Thanks Firoz Khan

I hope I can add to this discussion too :)

A Solar Cell is composed by a p-type and a n-type semiconductor materials placed together in physical contact.

So, a tiny region of very small thickness (could be up to 1 um, depending on the level of concentration of dopants) is created between the juntion of the p-type and the n-type materials (called a pn juction).

This region is called the Depletion region or the Space Charge (depleted) región. since the atoms of one side of this region are depleted of electrons (they end positively charged) and on the other side of the region the atoms end depleted of holes (they end negatively charged), so there is negative ions on one side and positive ions on the other, resulting in an induced Electric Field.

so, if you drop an electric charged particle within this region, the particle will move from one side of the pn union to the other.

Then you have your solar cell connected to an electric load, closing the circuit (meaning that if you have any current in the circuit, the electric charges in this current will flow throught the circuit.

Then, what happens when the solar cell operates under the sunlight is the following:

the photons which comes from the sun in the form of sunlight , can be viewed as an individual particles carrying a certain amount of linear momentum: (p=h/lamda). If these photons happen to carry a larger amount of energy than the energy needed to "promote" an electron from the valance band to the conduction band (the latter means: to provide the neccesary energy to an electron to get from the valance band (the energy band where the electrons are slightly tighted to its atoms) to the conduction band (the energy band where the electrons and more like delocalized in a less potential energy band (not so tighted to its atoms))

This amount of energy (the energy which must be carried by the photon) is equals or greater than the Energy Band gap of the semiconductor.

in this case we are interesting in having a not so large energy's band gap semiconductor material, so the light can generate electrons of conduction on the upper layer of the solar cell (we call this layer "the window layer", which it happens to be the n-type semiconductor of the solar cell structure, in almost the majority of the cases anyways).

So the photons enter from the upper side of the structure, and excite (detach from its valance atomic layer from the atom which it was linked) an electon (as explained above). This process is called an Electron-hole Pair Generation, since this electron is gonna continue linked (energetically linked, they are associated still (the lectron and the hole)) to the hole left by it, on its atomic valance band (this entity: the electron-hole pair is called an Exciton)

The concept of exciton then is useful to understand the last part of the process:

Then the Exciton travels on the direction of the pn juction (remember the process started on the n-type side) (electron and hole separated but energetically linked).

the Exciton reach the Depletion layer where the Electric Field has been established. , the Electric Field separates the electron from the hole, and since an electric load is connected to the circuit and the circuit is closed, there is a polarization on the circuit (i.e. at the both sides of the pn structure (or solar cell structure)).

So you will have an electron's current flowing to one side of the circuit and a hole's current flowing to the opposite side.

I hope it can bu useful !

Best Regards ! :)

Thank you so much, Franklin Uriel Parás Hernández