Optical properties of Si microwires combined with nanoneedles for flexible thin film photovoltaics.

A combined wire structure, made up of longer periodic Si microwires and short nanoneedles, was prepared to enhance light absorption using one-step plasma etching via lithographical patterning. The combined wire array exhibited light absorption of up to ~97.6% from 300 to 1100 nm without an anti-reflection coating. These combined wire arrays on a Si substrate were embedded into a transparent polymer. A large-scale wire-embedded soft film was then obtained by peeling the polymer-embedded wire portion from the substrate. Optically attractive features were present in these soft films, making them suitable for use in flexible silicon solar cell applications.