Highly efficient luminescent solar concentrators employing commercially available luminescent phosphors

Abstract

Luminescent solar concentrators (LSC) have great potential for providing solar energy at a competitive cost. They are simple devices employing a luminescent material embedded in a transparent sheet with solar cells attached on the edges. The luminescent material absorbs short wavelength solar radiation and emits red-shifted light. The emission is then guided towards the sheet edges, where the concentrated light is absorbed by the solar cell to produce electricity. The commercialization of luminescent solar concentrators has been stunted by an ongoing search for an adequate luminescent species that, among other things, is UV stable and inexpensive. While luminescent phosphors exhibit these characteristics, as well as other desirable qualities, their use in LSCs has received limited attention because they are highly scattering. Here, we demonstrate that luminescent solar concentrators can effectively employ scattering luminescent phosphors in the form of films. Monte Carlo simulations are used to investigate the optimum film location (top or bottom of the LSC) and concentration of phosphor within the film. The results show that when a film with a high phosphor concentration is placed at the bottom of the LSC, escape cone losses are lower than when the film is placed at the top, which increases light concentration within LSC. Four LSCs fabricated with commercially available materials, including the luminescent phosphor, are tested at varying incident angles using a full spectrum solar simulator. Moderate flux gains are achieved with efficiencies ranging from ~1.6 to 8.6%, depending on the angle of incidence and aspect ratio (AR). These results demonstrate the potential of luminescent phosphors for LSC applications.