Fluorescent polymer nanoparticles containing perylene diimides for application in luminescent solar concentrators

Abstract

Polymer nanoparticles containing perylene diimide-based fluorophores were designed as light harvesting materials in luminescent solar concentrators. Two perylene diimide structures were chosen so that they can operate as an energy donor and energy acceptor pair. In addition, the fluorophore design includes sterically bulky substituents to reduce dye aggregation and a methyl methacrylate linker for covalent incorporation into nanoparticles. Through emulsion polymerisation, nanoparticles with sizes ranging from 120 to 300 nm and with a dye loading between 1 and 2 wt% were obtained. The relatively high dye loading in the nanoparticles was targeted with the aim of enabling energy transfer between the dye molecules. The photophysical properties of the nanoparticle samples dispersed in water, chloroform, and the poly(methyl methacrylate) matrix were thoroughly investigated using a range of spectroscopic techniques. Evidence for energy transfer between dye molecules was obtained indicating successful confinement of dyes in the nanoparticles. The antenna effect in the dye loaded particles resulted in high photoluminescence quantum yields with a maximum of 91% obtained for the sample containing a 1 wt% energy donor dye and a 0.3 wt% energy acceptor dye. To assess the suitability of the nanoparticles in luminescent solar concentrators, Monte Carlo ray tracing simulations were performed to estimate the device performance yielding an optical quantum efficiency of 51% at a geometric gain of 62.5.