Exploring Electron-Hole Pairs in Solar Cells

[properphysicist]

When power is generated in a solar cell, it is because of irradiance of radiation on a pn-junction. But in which part of the junction are the electron-hole pairs created? Is it just the depleted region or are they also created in the n- and p-type semiconductors?

An engineer's response would be for me to consider a current source in parallel with a diode but I need a physicists response. What the heck is going on in a solar cell?

I'd be grateful for any help, thanks.

 

[ehild]

When power is generated in a solar cell, it is because of irradiance of radiation on a pn-junction. But in which part of the junction are the electron-hole pairs created? Is it just the depleted region or are they also created in the n- and p-type semiconductors?


I'd be grateful for any help, thanks.

The electron-hole pairs can be generated anywhere in a semiconductor, but they would recombine at once and nothing would happen unless they were formed in the depleted region and sucked away at opposite directions by the "built-in" electric field there. You know that positive charges are accumulated at the n type side near the junction and negative charges at the p type side. So the electron-hole pair will be separated, the electron moving into the n side and the hole moving into the p side. This results excess charge on both sides, and connecting the terminals you get current.


ehild

 

[properphysicist]

Thank-you echild. That answer is quite helpful.