Luminescent solar concentrators based on melt-spun polymer optical fibers

Abstract

Luminescent solar concentrators (LSCs) collect incoming sunlight and direct it to a smaller-area photovoltaic cell. In the presented work, form factor and illumination angle-dependent performance of LSCs consisting of bi-component melt-spun fibers is demonstrated. Three thermoplastic polymers act as dispersing host material for the luminescent dye Lumogen Red 305 (LR305). Molecular dynamics simulations provide numerical access to Hildebrand solubility parameters, which are an estimate for the mixing compatibility of dye with polymer matrix. Actual emission intensity measurements from material samples are compared to Monte Carlo ray tracing simulations. Some samples show an increased absorption, which led to the hypothesis that there exist optically passive dye aggregates if the dispersion is not optimal. The best-performing polymer/dye pair is identified and used to melt-spin fibers. Geometrically defined bundles of LSC fibers are studied in a scenario of white light illumination and variation of illumination-angle. This experiment simulates a theoretical daily course-of-sun illumination in absence of atmospheric effects. We report optical conversion efficiencies of the prepared LSCs between 2% and 15%, depending on illumination angle and bundle geometry. Keywords: Luminescent solar concentrators, Polymer optical fibers, Energy harvesting, Melt spinning