Silicon wire arrays, though attractive materials for use in photovoltaics and as photocathodes for hydrogen generation, have to date exhibited poor performance. Researchers at CalTech have now developed silicon microwire arrays that demonstrated solar energy conversion efficiencies of up to 3%, with the potential for further improvement. The paper appears in the 8 January issue of Science.
Internal quantum yields were at least 0.7, demonstrating that the measured photocurrents were limited by light absorption in the wire arrays, which filled only 4% of the incident optical plane in our test devices. The inherent performance of these wires thus conceptually allows the development of efficient photovoltaic and photoelectrochemical energy-conversion devices based on a radial junction platform.
—Boettcher et al.
The researchers using a copper-catalyzed, vapor-liquid-solid–growth process to grow ordered arrays of crystalline p-type silicon (p-Si) microwires on p+-Si(111) substrates, then used these wire arrays as photocathodes in contact with an aqueous methyl viologen2+/+ electrolyte.
Shannon W. Boettcher, Joshua M. Spurgeon, Morgan C. Putnam, Emily L. Warren, Daniel B. Turner-Evans, Michael D. Kelzenberg, James R. Maiolo, Harry A. Atwater, and Nathan S. Lewis (2010) Energy-Conversion Properties of Vapor-Liquid-Solid–Grown Silicon Wire-Array Photocathodes. Science Vol. 327. no. 5962, pp. 185 - 187 doi: 10.1126/science.1180783