Abstract
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 arrays 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.
| Original language | English |
|---|---|
| Pages (from-to) | 239-244 |
| Number of pages | 6 |
| Journal | Nature Materials |
| Volume | 9 |
| Issue number | 3 |
| DOIs | |
| Publication status | Published - Mar 2010 |
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ASJC Scopus subject areas
- Mechanical Engineering
- Mechanics of Materials
- Condensed Matter Physics
- Materials Science(all)
- Chemistry(all)
Cite this
Enhanced absorption and carrier collection in Si wire arrays for photovoltaic applications. / 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; Atwater, Harry A.
In: Nature Materials, Vol. 9, No. 3, 03.2010, p. 239-244.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Enhanced absorption and carrier collection in Si wire arrays for photovoltaic applications
AU - Kelzenberg, Michael D.
AU - Boettcher, Shannon W.
AU - Petykiewicz, Jan A.
AU - Turner-Evans, Daniel B.
AU - Putnam, Morgan C.
AU - Warren, Emily L.
AU - Spurgeon, Joshua M.
AU - Briggs, Ryan M.
AU - Lewis, Nathan S
AU - Atwater, Harry A.
PY - 2010/3
Y1 - 2010/3
N2 - 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 arrays 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.
AB - 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 arrays 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.
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U2 - 10.1038/nmat2635
DO - 10.1038/nmat2635
M3 - Article
VL - 9
SP - 239
EP - 244
JO - Nature Materials
JF - Nature Materials
SN - 1476-1122
IS - 3
ER -