Improvement of the light-trapping effect using a subwavelength-structured optical disk

The subwavelength structures formed by data tracks in an optical disk are applied to improve the light-trapping effect for thin-film amorphous silicon (a-Si) solar cell applications. An antireflection coating (ARC) consisting of at least two dielectric layers (SiO2 and ZnS─SiO2) is designed for the top planar surface of the disk. The a-Si thin-film solar cell layer is deposited below the bottom surface of the disk. Finally, a reflective metal coating is attached to the a-Si layer to fully reflect the incident light and extend the round-trip light path. With the proposed configuration, the reflectance and absorptance can be effectively decreased and enhanced by more than 10% compared with those without ARC and structured surfaces.