Indium Tin Oxide Photonic Crystal for Controllable Light Coupling in Solar Cells by an Inexpensive Soft Lithography with HD-DVD and Blu-ray

We present an indium tin oxide/polymethylsilsesquioxane (ITO/PMSSQ) photonic crystal with grating structure. This topography exhibits multiple coupling resonances in specific regions of the solar spectrum, which can be controlled by tuning the angle and polarization of incident light. The ITO/PMSSQ grating structures are prepared via simple soft lithography procedures using HD-DVDs as templates. The surface topology also includes geometrical singularities such as nanogaps and nanocones, which lead to further enhanced light trapping characteristics as demonstrated by theoretical and experimental results. Together, these singularity-embedded photonic crystal gratings result in extremely concentrated electromagnetic fields at the aforementioned singularities, which could be especially helpful in separating the tightly bonded excitons in organic solar cells and, hence, improve the efficiency significantly.