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.
Kelzenberg, M.D., Boettcher, S.W., Petykiewicz, J.A., Turner-Evans, D.B., Putnam, M.C., Warren, E.L., Spurgeon, J.M., Briggs, R.M., Lewis, N.S., and Atwater, H.A., “Enhanced absorption and carrier collection in Si wire arrays for photovoltaic applications”, Nature Materials
, 239-2441 (2010) [DOI:10.1038/nmat2635