eli5: Do solar panels only work with sunlight, or can they be tuned to capture energy from other wavelengths outside the visible spectrum?

Question

eli5: Do solar panels only work with sunlight, or can they be tuned to capture energy from other wavelengths outside the visible spectrum?

In: 2876

Answer 1

Any photon with energy greater than the bandgap of the material of which the PV cell is made can be absorbed. However most of the sunlight energy is in the near infrared and visible regions.

Silicon has a bandgap of ~1.12 eV (wavelength less than 1100nm), so any photon with greater energy will be absorbed, and energy in excess of 1.12 eV per photon will be dissipated as heat. There are some technicalities which reduce the absorption efficiency near the 1100nm.

If you want more efficient PV cell at shorter wavelengths you can go to a material with greater bandgap.

If you want to absorb 1500 nm you can go to lower band gap energy like indium phosphide.