One problem with solar cells is that the thicker and more powerful they are, the more expensive they are to make. However engineers at Stanford recently announced that they have developed a new type of solar cell thinner than the wavelengths of light that could absorb 10 times the amount of sunlight that current cells do. The engineers believe that by configuring the thicknesses of several thin layers of films, an organic polymer cell could transform the solar energy industry.
Stanford’s new ultra-thin solar cell stops the lights from bouncing around as it would in a conventional cell, allowing it to be absorbed more easily. This technique is called “light trapping”, and it works best in nano-thin cells. Speaking to PhysOrg.com, Shanhui Fan, associate professor of electrical engineering said, “It’s the same as if you were using hamsters running on little wheels to generate your electricity – you’d want each hamster to log as many miles as possible before it jumped off and ran away.”
“The longer a photon of light is in the solar cell, the better chance the photon can get absorbed,” Fan added, who is also senior author of the paper describing the work called Proceedings of the National Academy of Sciences. “We all used to think of light as going in a straight line,” Fan said. “For example, a ray of light hits a mirror, it bounces and you see another light ray. That is the typical way we think about light in the macroscopic world. But if you go down to the nanoscales that we are interested in, hundreds of millionths of a millimeter in scale, it turns out the wave characteristic really becomes important.”
With that in mind, if a solar cell can be made that is around 400 to 700 nanometers thin (billionths of a meter), it can produce a remarkable amount of energy. The potential for this technology is enormous — not only would nano-thin solar cells save money in materials, but by using organic polymers over silicon they make the cells cheaper to buy and easier to install due to their thickness.