Inexpensive Solar Cell with Near Perfect Quantum Efficiency
March 3, 2010 :: Researchers at the DOE Energy Frontier Research Center (EFRC) led by the California Institute of Technology have demonstrated for the first time that the conventional light-trapping limit for absorbing materials can be surpassed. They have created a new type of flexible solar cell that enhances the absorption of sunlight and efficiently converts its photons into electrons using arrays of long, thin silicon wires embedded in a polymer substrate. The new silicon wire arrays created are able to convert between 90 and 100 percent of the photons they absorb into electrons, with near-perfect internal quantum efficiency. Since each silicon wire measures between 30 and 100 microns in length and only 1 micron in diameter, in terms of area or volume, just 2 percent of it is silicon, and remainder 98 percent is polymer, making the solar cells much cheaper to produce, possibly manufactured in a roll-to-roll process. Findings were reported in the advance online edition of the journal Nature Materials. The work was supported by BES and by BP.
