Direct Light-Writing of Nanoparticle-Based Metallo-Dielectric Optical Waveguide Arrays Over Silicon Solar Cells for Wide-Angle Light Collecting Modules

Here presented are the properties and performance of a new metallo-dielectric waveguide array structure as the encapsulation material for silicon solar cells. The arrays are produced through light-induced self-writing combined with in situ photochemical synthesis of silver nanoparticles. Each waveguide comprises a cylindrical core consisting of a high refractive index polymer and silver nanoparticles homogenously dispersed in its medium, all of which are surrounded by a low refractive index common cladding. The waveguide array-based films are processed directly over a silicon solar cell. Arrays with systematically varied concentration of AgSbF6 as the salt precursor are explored. The structures are tested for their wide-angle light capture capabilities, specifically toward enhanced conversion efficiency and current production of encapsulated solar cells. Observed are increases in the external quantum efficiency, especially at wide incident angles up to 70 degrees, and nominal increases in the short circuit current density by 1 mA cm(-2) (relative to an array without nanoparticles). Enhanced light collection is explained in terms of the beneficial effect of scattering by the nanoparticles along the waveguide cores. This is a promising approach toward solar cell encapsulants that aid to increase solar cell output over both the course of the day and year.