Enhanced absorption in silicon nanocone arrays for photovoltaics

Silicon nanowire arrays have been shown to demonstrate light trapping properties and promising potential for next-generation photovoltaics. In this paper, we performed systematic and detailed simulation studies on the optical properties of silicon nanocone arrays as compared to nanowires arrays. Nanocone arrays were found to have significantly improved solar absorption and efficiencies over nanowire arrays. Detailed simulations revealed that nanocones have superior absorption due to reduced reflection from their smaller tip and reduced transmission from their larger base. The enhanced efficiencies of silicon nanocone arrays were found to be insensitive to tip diameter, which should facilitate their fabrication. Breaking the vertical mirror symmetry of nanowires results in a broader absorption spectrum such that overall efficiencies are enhanced. We also evaluated the electric field intensity, carrier generation and angle-dependent optical properties of nanocones and nanowires to offer further physical insight into their light trapping properties.