Thirty Years of Luminescent Solar Concentrator Research: Solar Energy for the Built Environment

Abstract

Research on the luminescent solar concentrator (LSC) over the past thirty‐odd years is reviewed. The LSC is a simple device at its heart, employing a polymeric or glass waveguide and luminescent molecules to generate electricity from sunlight when attached to a photovoltaic cell. The LSC has the potential to find extended use in an area traditionally difficult for effective use of regular photovoltaic panels: the built environment. The LSC is a device very flexible in its design, with a variety of possible shapes and colors. The primary challenge faced by the devices is increasing their photon‐to‐electron conversion efficiencies. A number of laboratories are working to improve the efficiency and lifetime of the LSC device, with the ultimate goal of commercializing the devices within a few years. The topics covered here relate to the efforts for reducing losses in these devices. These include studies of novel luminophores, including organic fluorescent dyes, inorganic phosphors, and quantum dots. Ways to limit the surface and internal losses are also discussed, including using organic and inorganic‐based selective mirrors which allow sunlight in but reflect luminophore‐emitted light, plasmonic structures to enhance emissions, novel photovoltaics, alignment of the luminophores to manipulate the path of the emitted light, and patterning of the dye layer to improve emission efficiency. Finally, some possible ‘glimpses of the future’ are offered, with additional research paths that could result in a device that makes solar energy a ubiquitous part of the urban setting, finding use as sound barriers, bus‐stop roofs, awnings, windows, paving, or siding tiles.

A borane laser

“…Another advantage of incorporating chromophores into polymers is that the solid material may be cast as thin films acting as wave-guiding active devices. In fact, there has been significant work over the last few years exploring the development of these types of devices because of their potential applications as coherent light sources suitable for integration in optoelectronic and disposable spectroscopic and sensing devices 30,31 , as well as its use as luminescent solar concentrators for energy-harvesting applications 32 . In this regard, the boranes might be a potential candidate, as chromophores in luminescent solar concentrators should have minimal reabsorption (large Stokes shifts), fluorescence quantum yields above 0.90 and high photostabilities 33 , requirements that are fulfilled by the fluorescent boron hydride, anti-B 18 H 22 .…”

Nanophotonic luminescent solar concentrators

“…These can be divided into two groups based on the wavevector in the LSC plane (k ): non-waveguided (ω ≥ c|k |) and total internally reflected (TIR, ω < c|k |) modes. In conventional LSCs, lumophore-filled waveguides of refractive index n much thicker than the luminescence wavelength, the fraction f tirof photonic modes corresponds to TIR modes [1]. According to ray tracing simulations, photons emitted into non-waveguided modes are lost into air after multiple reflections [5].…”

“…Finite-difference time-domain electromagnetic simulations show that the waveguided luminescence photon flux can be enhanced up to 30% for the photonic crystal design over a conventional LSC operating in the ray optic limit assuming the same number of excited lumophores. Further photonic engineering could realize an increase of up to one order of magnitude in the flux of waveguided luminescence.The luminescent solar concentrator (LSC) could decrease the installed cost of solar energy through building integration [1]. The LSC, a semi-transparent waveguide with embedded lumophores, concentrates sunlight by frequency downconversion; the lumophores absorb diffuse incident sunlight and luminesce at a redder, Stokesshifted wavelength.…”

Luminescent Solar Concentration with Semiconductor Nanorods and Transfer-Printed Micro-Silicon Solar Cells

“…In practice, such high concentration is elusive and LSC devices have to date been limited to concentration factors around 10. 6 The disparity between ideal and real luminescent solar concentrators is due to incomplete trapping of luminesced light and nonunity fluorescence quantum yields. 7,8 The root of this problem is excessive overlap between lumophore absorption and emission spectra.…”