Light trapping in Silicon-Film™ solar cells with rear pigmented dielectric reflectors

This paper presents the novel method of using pigmented dielectric reflectors to provide light trapping in thin-film silicon solar cells. This type of reflecting material offers many potential advantages over specular metallic reflectors, including low cost, compatibility with high temperatures common to solar cell processing, and high, broadband and diffuse reflectance. As this is the first time this concept is described, the basic theory of the optical behavior of pigmented materials is presented by connecting the basic material properties of pigment and medium to their light-trapping benefit in thin silicon solar cells. Several general principles leading to maximum light-trapping benefit are identified, and experimental evidence is presented corroborating these general principles. Light trapping is demonstrated in thin silicon solar cells with pigmented dielectric reflectors by measurement and analysis of external quantum efficiency curves.