CONFORMAL FILMS FOR LIGHT-TRAPPING IN THIN SILICON SOLAR CELLS

摘要

A light-trapping structure (10) comprises a base material (11) having at least a first face (12) textured with a texture (13) of period T and comprised of facets (14, 15, 16, 17...). Laid on or otherwise attached to the facets of the texture (13) is a film (18) which is continuous and sufficiently thin that it conforms in its profile to the texture (13). The film (18) will thus be shaped in conformance with the texture (13) to have a period T. Ideally the film (18) is of substantially constant thickness (t). In use according to a preferred embodiment of the invention the base material (11) is light reflective, at least at the facets (14, 15, 16, 17) comprising the texture (13) whereby light rays such as light ray (19) treat the facets as a mirror and are thereby reflected according to the laws of light reflection from a surface so as to be reflected off other facets of the texture (13). Where the refractive index of the film (18) is different from the refractive index of the layer on top of it, internal reflection can occur at the boundary between these layers. In the case of a thin film silicon solar cell the base material (11) can comprise a substrate of glass to which a thin film (18) of doped silicon is applied. Additional films (not shown) can be applied on top to create a multi-layer thin film silicon solar cell with the various layers doped appropriately and the whole covered in a glass encapsulant (20). In one form the texture (13) is three-dimensional as defined in the specification.