Waveguide-imprinted slim polymer films: beam steering coatings for solar cells

We report that transparent polymer coatings imprinted with tilted planar waveguides significantly reduce optical loss caused by scattering of incident light by the front metal contacts of solar cells. A periodic array of planar waveguides oriented at specific angles with respect to the film’s surface normal efficiently captures and steers incident light away from contacts and in this way, suppresses scattering. These beam steering films are fabricated in a single, room temperature step by self-trapped incandescent beams, which inscribe multimode planar waveguides oriented at angles ranging from 0 to 2.7 in photopolymerizable epoxide resin. We characterized the microstructural and optical properties of the films and demonstrated their ability to deflect incident white light – comparable to sunlight - by as much as 180 m from the typically . Solar cells coated with beam steering films showed significant enhancements in external quantum efficiency (EQE) of up to 4.42 % relative to unstructured films. This fi...