Optical Properties of Silicon Microwire Arrays for Photovoltaic Applications
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- Institutt for fysikk 
Silicon microwire-based solar cells represent a potential design strategy to reduce wafer related costs through reduced material usage and relaxed purity requirements. In this work we investigate the absorption of incident solar radiation achievable in two designs using microwires produced from a molten core fiber drawing method. The first consists of vertically aligned wires each surrounded by an etched conical cavity that served as a light trapping structure, while the second consists of horizontally-aligned wires on a substrate. Modeling explored the absorption of both designs as a function of various geometrical and optical parameters relevant to cell design, while experimental absorption measurements were conducted on horizontal arrays using a home-built integrating sphere setup. The results demonstrated over 70\% absorption of the solar spectrum in both these designs despite reduced silicon per unit cell area and without anti-reflection coatings. The results highlight the potential of silicon microwire-based solar cells to reduce costs while maintaining high absorption, as well as other potential uses as semi-transparent cells in the case of the horizontal design.