Fabrication of highly transparent self-cleaning protection films for photovoltaic systems

A moth-eye anti-reflective structure was fabricated by hot-embossing and UV nanoimprint lithography on a solar cell protective film to suppress the reflection of incident light. Moreover, a superhydrophobic surface was developed by reducing the surface energy by forming a hydrophobic self-assembled monolayer coating on an anti-reflective structured resin surface. Therefore, the transmittance of incident light was increased by the anti-reflective structure. As a result, the solar cell efficiency was enhanced and the total accumulated electrical energy generated by a solar cell with a nano-patterned polymeric film was increased. The efficiency of each solar cell was evaluated by an analysis of its I-V characteristics using a solar simulator, and the external quantum efficiency according to the wavelength of incident light was analyzed by using an incident photon-to-current conversion efficiency system. Finally, the enhancement of the generated power was confirmed by a field test and a power charging experiment. Copyright (c) 2012 John Wiley & Sons, Ltd.