Silicon solar cells currently are, at a maximum, between 19% and 50% efficient converting solar energy into electricity. The rest of that energy is lost to heat and reflection, as well as resistance in the cells themselves. Part of the problem is that silicon solar cells can only be made reactive to a certain part of the spectrum. Multijunction solar cells are pushing efficiency ever upwards, but these processes are expensive and fragile.
Research into nanomaterials has led to ever greater discoveries into the nature of materials, especially as they change from macromaterials. Nanowires could change the face of solar cell technology as we know it, due to a couple of interesting characteristics of nanowires. First, nanowires are so small, smaller than a wavelength of light, they can absorb almost all of the photons in that wavelength. Second, nanowires are so small that only 10% of the surface area is required to generate the same amount of power as a silicon solar cell.
Researchers from Lund University in Sweden have been working with nanowires to create more efficient solar cells. “Our findings are the first to show that it really is possible to use nanowires to manufacture solar cells”, says Magnus Borgström, a Lund researcher in semiconductor physics. Currently, nanowire solar cells are up to about 13.8% efficiency, or about the same as commercially-available solar cells. Researchers are currently working to optimize the length of the nanowires, just a few tenths of a nanometer, is critical in the absorption of light to convert to electricity. Once this process is perfected, they could realize solar panels near 100% efficiency and in a smaller format. Additionally, nanowire solar cells ought to be less expensive in production than current silicon solar cell technology.
