solar cells

One idea I've been researching in the last year is using photonic crystals to improve solar cells. The biggest problem with solar cells right now is that they're too expensive compared to other sources of energy, even if they work perfectly for 20 years. The root of this problem is a lack of solar cell efficiency. In silicon solar cells made by the industry, only 12-16% of light coming from the sun is converted into electricity; in laboratory silicon cells, about 30% efficiency can be achieved.

Our idea is to introduce photonic crystals into the solar cells to improve the light trapping properties. This takes place via two mechanisms. First, the photonic crystal diffracts incoming light into modes that are internally reflected within the silicon, thereby converted the solar cell into a waveguide. Second, the photonic crystal refracts light into crystal modes that are confined to bounce back and forth inside the photonic crystal until they're absorbed. When you combine these two effects, we estimate that you could improve the efficiency for 20% for normal incidence. For off-angle incidence, we're currently investigating what should happen. We've already filed for a patent and have started a business idea related to licensing this technology. In the next posts I'll go into more detail about the details of the light trapping as well as the business model.