We use electromagnetic simulations to study the effects of nanoscale patterning on light absorption in thin films for photovoltaic applications. We focus on vertically oriented semiconductor nanowire arrays and identify design rules for increasing broadband absorption across the solar spectrum. We quantify absorption by calculating the ultimate efficiency, an upper bound on efficiency that assumes perfect carrier collection.For crystalline silicon nanowires, we have shown that optimized periodic arrays have higher ultimate efficiency than unpatterned films, though they contain less absorptive material. Further, we have used optimal design strategies to demonstrate aperiodic structures with >100% absorption increase relative to their periodic counterparts.We have further studied broadband absorption in nanowire arrays made of Ge, InP, GaAs, CdTe, and GaInP, all common photovoltaic materials. We have verified that optimized arrays are more absorptive than thin films over a wide range of heights. Our results provide a roadmap for nanowire array efficiencies.

Modeling of light trapping effects in nanowire photovoltaic cells

243rd National Meeting (2012)

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