Luminescent solar concentrators consist of a flat pane of transparent material doped with dye fluorophores; some of the sunlight absorbed by the dye is re-emitted and totally internally reflected to the edges of the pane, where photovoltaic cells collect it. Such a setup concentrates light without the need for tracking the sun, and can even concentrate light on cloudy days. However, the efficiency of a conventional luminescent concentrator cannot be boosted above about 10%, due to reabsorption losses, escape-cone losses, and low spectral efficiency.
But this limit does not hold if silver nanoparticles are added to the concentrator, at least according to a hybrid nanoscale/macroscale simulation done by a group at University College London (London, England). The model predicts a phenomenal rise in normalized optical efficiency from 10.4% to 32.6% when silver nanospheres are immersed in one or more thin dye layers (sandwiched between undyed, nanosphere-lacking layers). The researchers modeled three configurations: nanospheres, nanoshells, and flat discs (with the discs placed atop the dye layer), with particle radii of 30, 50, or 70 nm and varying concentrations of particles, for concentrator pane sizes from 50 to 1000 mm on a side. Nanospheres worked best, resulting in an efficiency of 23.7% for one plasmonic layer and 32.6% for three layers (each layer 600 nm thick with a nanoparticle coverage of 12.3%). The efficiency enhancement is due mostly to scattering by the particles. Contact Clemens Tummeltshammer at [email protected].
