Integrating Photonics with Luminescent Solar Concentrators: Optical Transport in the Presence of Photonic Mirrors

Luminescent solar concentrators downshift and concentrate the incident solar spectrum onto adjacent solar cells. In this paper we study the combination of highly performing luminescent nanocrystals with photonic structures to guide light to the edge of the concentrator. While one approach is to use a wavelength-selective Bragg mirror to reduce escape cone losses, we find that this also requires nearly perfect mirrors and luminophore quantum yield. The key issue is that light is trapped inside the concentrator in modes that inefficiently propagate toward the edge, leading to luminophore reabsorption and losses to imperfect mirrors. To overcome this difficulty, we use modeling to study the use of meta-mirrors that shift propagating photons to larger angles, minimizing interactions with the reabsorbing luminophores and mirrors. We find that this design favors mirrors with small changes in angle, separated from the luminophore polymer layer by an air gap. This research indicates that a combination of photonic structures can be used with imperfect luminescent materials and mirrors to enable high optical efficiency from luminescent concentrators.