Chicago’s Northwestern University researchers were working on making thin-film solar cells more efficient when they turned to nature to help refine their design: evolution by natural selection. Solar cells trap light in order to absorb solar energy. Thin cells make it unlikely that energy will be captured efficiently.
In order to make it more likely that a light photon will be captured in the photovoltaic layer and be turned into electrical power, the researchers decided to add a scattering layer to the cells. This layer deflects incoming light in all directions, potentially bouncing the light back and forth inside the film.
This is where the team decided to leverage the power of natural selection. They used a number of computer generated scattering patterns and analyzed how each of the patterns would scatter light. They then “mated” the patterns and generated likely “offspring.” The second generation patterns that did a better job of scattering light were “bred” with other highly efficient patterns.
The end result traps light for three times the span predicted in older models of how light and cells interact. This is amazing news for solar cell efficiency. The longer the light remains in the cell, the more likely its power will be trapped and converted by the PV layer.