Omnidirectional and Wideband Absorption of Solar Radiation with Light Funnel Arrays Incorporated with Quasi-Nanolenses

Broadband absorption of solar photons is a perquisite for any application concerning harvesting of solar energy. The current study shows excellent broadband absorption of the solar spectrum with arrays composed of light funnel arrays integrated with top nanolenses. Light funnel arrays provide high broadband absorption governed by low transmission levels. However, light funnel arrays suffer from relatively high reflection. Herein we show how the broadband absorption is governed by the inherent low transmission levels induced by the light funnel geometry coupled with efficient broadband reflection decrement induced by the presence of top nanolenses. The integration of nanopillar arrays and light funnel arrays with nanolenses is examined. The light funnel geometry provides a more favorable optical coupling with nanolenses with a broadband absorption enhancement of ∼12% under normal illumination. The enhancement in the broadband absorption of light funnel arrays due to nanolenses is also examined and confirmed for oblique illumination. Photovoltaic cells based on light funnel arrays with nanolenses are numerically realized and an increase of ∼10% in short-circuit current is demonstrated. Finally, the associated light trapping mechanisms are qualitatively discussed.