Details

Autor(en) / Beteiligte

• Atwater, Harry A
• Kelzenberg, Michael D
• Boettcher, Shannon W
• Petykiewicz, Jan A
• Turner-Evans, Daniel B
• Putnam, Morgan C
• Warren, Emily L
• Spurgeon, Joshua M
• Briggs, Ryan M
• Lewis, Nathan S

Titel

Enhanced absorption and carrier collection in Si wire arrays for photovoltaic applications

Ist Teil von

• Nature materials, 2010-03, Vol.9 (3), p.239-244

Ort / Verlag

London: Nature Publishing Group UK

Erscheinungsjahr

2010

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Si wire arrays are a promising architecture for solar-energy-harvesting applications, and may offer a mechanically flexible alternative to Si wafers for photovoltaics. To achieve competitive conversion efficiencies, the wires must absorb sunlight over a broad range of wavelengths and incidence angles, despite occupying only a modest fraction of the array's volume. Here, we show that arrays having less than 5% areal fraction of wires can achieve up to 96% peak absorption, and that they can absorb up to 85% of day-integrated, above-bandgap direct sunlight. In fact, these arrays show enhanced near-infrared absorption, which allows their overall sunlight absorption to exceed the ray-optics light-trapping absorption limit for an equivalent volume of randomly textured planar Si, over a broad range of incidence angles. We furthermore demonstrate that the light absorbed by Si wire arrays can be collected with a peak external quantum efficiency of 0.89, and that they show broadband, near-unity internal quantum efficiency for carrier collection through a radial semiconductor/liquid junction at the surface of each wire. The observed absorption enhancement and collection efficiency enable a cell geometry that not only uses 1/100th the material of traditional wafer-based devices, but also may offer increased photovoltaic efficiency owing to an effective optical concentration of up to 20 times.