Using colloidal lithography to fabricate and optimize sub-wavelength pyramidal and honeycomb structures in solar cells

The external quantum efficiency of solar cells can be improved by using texturing pyramid- and honeycomb-like structures with minimum reflection. In this study, we investigated the reflection properties of texturing structures through rigorous coupled-wave analysis and the three-dimensional finite-difference time domains (FDTD) method to analyze close-packed texturing structures. We also demonstrate a simple method combining sub-wavelength-scale monolayer and bilayer polystyrene spheres with a one-step reactive ion etching process-to fabricate optimized pyramid- and honeycomb- shaped antireflection structures, respectively. Thus, sub-wavelength pyramidal and honeycomb- like structures displaying low reflectance were obtained readily without the need for any lithography equipment. (C) 2007 Optical Society of America.