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 similar 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. (C)2010 Optical Society of AmericaThis work was supported by the Pioneer Research Center Program (No. 2010-0002231), Mid-Career Researcher Program (No. 2010-0000231), and Nano R&D Program (No. 20090083229) through the National Research Foundation (NRF) grant funded by the Ministry of Education, Science and Technology (MEST). This work was supported by the New & Renewable Energy of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea Government Ministry of Knowledge Economy (No. 2009T100100614). In addition, we are grateful to the National Nanofab Center for technical assistance. K.-T. Park and H.-D. Um acknowledge the financial support of the fifth-stage Brain Korea 21 Project in 2010