Boosting Solar Cell Photovoltage via Nanophotonic Engineering.
Approaching the theoretically limiting open circuit voltage (Voc) of solar cells is crucial to optimize their photovoltaic performance. Here, we demonstrate experimentally that nanostructured layers can achieve a fundamentally larger Fermi level splitting, and thus a larger Voc, than planar layers. By etching tapered nanowires from planar indium phosphide (InP), we directly compare planar and nanophotonic geometries with the exact same material quality. We show that the external radiative efficiency of the nanostructured layer at 1 sun is increased by a factor 14 compared to the planar layer, leading to a 70 mV enhancement in Voc. The higher voltage arises from both the enhanced outcoupling of photons, which promotes radiative recombination, and the lower active material volume, which reduces bulk recombination. These effects are generic and promise to enhance the efficiency of current record planar solar cells made from other materials as well.
Applied Physics, Eindhoven University of Technology , P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
Y
Y
Cui
Applied Physics, Eindhoven University of Technology , P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
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D
van Dam
Center for Nanophotonics, FOM Institute AMOLF , 1098 XG Amsterdam, The Netherlands.
S A
SA
Mann
Applied Physics, Eindhoven University of Technology , P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
N J J
NJ
van Hoof
Applied Physics, Eindhoven University of Technology , P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
P J
PJ
van Veldhoven
Center for Nanophotonics, FOM Institute AMOLF , 1098 XG Amsterdam, The Netherlands.
E C
EC
Garnett
Applied Physics, Eindhoven University of Technology , P.O. Box 513, 5600 MB Eindhoven, The Netherlands.|Kavli Institute of Nanoscience, Delft University of Technology , 2600 GA Delft, The Netherlands.
E P A M
EP
Bakkers
Applied Physics, Eindhoven University of Technology , P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
J E M
JE
Haverkort
Nanophotonics; nanowires; open circuit voltage; photovoltage; photovoltaics