| Autor: |
Chen IJ; NanoLund and Solid State Physics, Lund University, Box 118, SE-22100 Lund, Sweden., Limpert S; NanoLund and Solid State Physics, Lund University, Box 118, SE-22100 Lund, Sweden., Metaferia W; NanoLund and Solid State Physics, Lund University, Box 118, SE-22100 Lund, Sweden.; National Renewable Energy Laboratory, Golden, Colorado 80401, United States., Thelander C; NanoLund and Solid State Physics, Lund University, Box 118, SE-22100 Lund, Sweden., Samuelson L; NanoLund and Solid State Physics, Lund University, Box 118, SE-22100 Lund, Sweden., Capasso F; Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States., Burke AM; NanoLund and Solid State Physics, Lund University, Box 118, SE-22100 Lund, Sweden., Linke H; NanoLund and Solid State Physics, Lund University, Box 118, SE-22100 Lund, Sweden. |
| Abstrakt: |
Nanowires bring new possibilities to the field of hot-carrier photovoltaics by providing flexibility in combining materials for band engineering and using nanophotonic effects to control light absorption. Previously, an open-circuit voltage beyond the Shockley-Queisser limit was demonstrated in hot-carrier devices based on InAs-InP-InAs nanowire heterostructures. However, in these first experiments, the location of light absorption, and therefore the precise mechanism of hot-carrier extraction, was uncontrolled. In this Letter, we combine plasmonic nanoantennas with InAs-InP-InAs nanowire devices to enhance light absorption within a subwavelength region near an InP energy barrier that serves as an energy filter. From photon-energy- and irradiance-dependent photocurrent and photovoltage measurements, we find that photocurrent generation is dominated by internal photoemission of nonthermalized hot electrons when the photoexcited electron energy is above the barrier and by photothermionic emission when the energy is below the barrier. We estimate that an internal quantum efficiency up to 0.5-1.2% is achieved. Insights from this study provide guidelines to improve internal quantum efficiencies based on nanowire heterostructures. |
