Impact of Attaching Selectively Reflecting Cholesteric Layers on Edge Output of Static and Dynamic Luminescent Solar Concentrators

Luminescent solar concentrators offer a versatile option for renewable electricity generation for deployment in the built environment. The primary challenge of these devices remains the reduction of various losses that limit them to modest efficiencies. Wavelength-selective chiral nematic (cholesteric) liquid crystal reflectors with air gaps are found to yield promising results in the past, reducing surface losses and increasing edge emissions. Herein, the influence of directly attached cholesteric reflectors on the edge outputs of both static and switchable “smart window” luminescent solar concentrator lightguides is investigated. For lightguides containing a coumarin dye, an increase in edge photon emission of at least 30% (from 2.2% to 2.9% external photon efficiency) is achieved when using full reflectors at both top and bottom of both static and dynamic lightguides with a central reflection wavelength centered at 600 nm, ≈70 nm red-shifted to the dye emission peak.