Gallium nanoparticles as antireflection structures on III-V solar cells

Abstract

The integration of nanostructures on top of solar cells has been previously demonstrated as an effective method to increase the collection efficiency by coupling to sunlight. In this work, this approach is implemented by using core-shell gallium nanoparticles (Ga-NPs) as functional light scatterers on III-V solar cells, investigating how the Ga-NPs affect their photovoltaic performance. The effect is studied in GaAs and in GaAsSbN superlattice-based solar cells with different bandgaps for a wide range of Ga-NPs sizes. After NP size optimization, average improvements in the short-circuit current around 18 % are obtained in both types of solar cells with these nanostructures. The underlying physical mechanism is studied by performing optical measurements and simulations. It is found that the Ga-NPs can be treated as an antireflection coating due to both their geometry and the refractive index in the cases when their localized surface plasmon resonances do not spectrally overlap with the solar cell absorption range. Lastly, a facile method to attenuate the plasmonic effect of the Ga-NPs it is also shown as a proof of concept. In this method, an annealing treatment at low temperature is performed causing an improvement of the photovoltaic performance. This work demonstrates that Ga-NPs can successfully enhance the efficiency of III-V solar cells in a very controllable manner and paves the way for the design of new functional nanostructures.