Absorption and Conduction

In a PV cell, photons are absorbed in the p-layer. And it's very important to "tune" this layer to the properties of incoming photons to absorb as many as possible, and thus, to free up as many electrons as possible. Another challenge is to keep the electrons from meeting up with holes and recombining with them before they can escape from the PV cell. To do all this, we design the material to free the electrons as close to the junction as possible, so that the electric field can help send the free electrons through the conduction layer (the n-layer) and out into the electrical circuit. By optimizing all these characteristics, we improve the PV cell's conversion efficiency, which is how much of the light energy is converted into electrical energy by the cell.

Illustration of how absorption, reflection, recombination and conduction work within a PV cell.

To make an efficient solar cell, we try to maximize absorption, minimize reflection and recombination, and thus maximize conduction.

See these pages for more information on crystalline silicon solar cells:

To learn more about PV physics, see:

The Photoelectric Effect