Solar highways: core-shell nanowires for high-efficiency solar conversion
Erik Garnett, Sander Mann, Beniamino Sciacca, Sebastian Oener, Cristina Sfiligoj, Michiel de Goede
FOM Institute AMOLF
The ideal solar cell would convert light into photogenerated carriers in an infinitely small volume. Such a structure not only limits material usage but also relaxes carrier diffusion length requirements and maximizes the output voltage. Here we describe a novel geometry consisting of a metal nanowire covered by an ultrathin semiconductor layer, which shows extreme light absorption enhancement. We present a theoretical model to explain why this structure works so well in both polarizations of light and use full-field simulations to demonstrate robust performance even with geometrical perturbations. We begin experimental work with a model system consisting of a silver nanowire core and cuprous oxide shell. These core-shell nanowires are synthesized at low temperature in solution and here we will present electron microscopy showing that they are single-crystalline with atomically sharp and coherent interfaces. We will present spatially-resolved, single nanowire optical and electrical measurements (reflection, scattering, absorption, photocurrent, solar cell I-V curves) taken using an integrating sphere and compare the results quantitatively to simulations. We will end by proposing a novel nanophotonic spectral splitting scheme that takes advantage of the high optical cross-sections of our core-shell antenna. Our experiments suggest that this solar highways geometry should be explored further for photovoltaics and solar fuels applications.