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

Abstract

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°, 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.

Light-Directed Organization of Polymer Materials from Photoreactive Formulations

“…Previous studies have shown that photopolymer nanoparticle formulations can undergo self-trapping, , with the presence of the nanoparticles not being deleterious to the process. Our recent work on the in situ production of nanoparticles in filaments is also a step in this general direction …”

“…These advances have included the concurrent self-trapping of multiple microscale beams in different photoinitiated media, as well as self-trapping in different polymeric media, such as blends and photopolymer–solvent mixtures. This has led to an understanding of the underlying photopolymer reaction kinetics, diffusion, and dynamics and the resultant structures, which are discussed herein, as well as a range of functional applications, ,− whose in-depth discussion is beyond the scope of this perspective.…”

“…These two performance criteria could be optimized through varying the filament size and spacing as well as the relative weight fractions of the components, the last of which improves the contiguous nature of the filaments, which is favorable for waveguiding . Further enhancements were also found when silver nanoparticles were grown in situ via photochemical reduction of a silver salt, producing metallo-dielectric waveguides with wider collection windows owing to the enhancement from nanoparticle scattering …”

“…The effects of other parameters, such as χ and weight fraction and even particle size, are proposed in Figure b as to how they will shift the boundary. Nanoparticles may also be synthesized in situ during the self-writing process, enabling possibly high-χ systems to be organized …”

“…26 Further enhancements were also found when silver nanoparticles were grown in situ via photochemical reduction of a silver salt, producing metallo-dielectric waveguides with wider collection windows owing to the enhancement from nanoparticle scattering. 28 3.4. Photopolymer−Solvents.…”