Among the various forms of renewable energy, solar energy is one of the most conventional and widely used. Therefore, photovoltaic (PV) technology has become much accessible and more efficient, and research to develop more innovative panels is progressing. Recently, efforts are being made to develop more aesthetically pleasing PV devices that can be better integrated into urban buildings as integrated PV (BIPV).

In this context, luminescent solar concentrators (LSC) offer a straightforward strategy to harvest, spectrally convert and optically concentrate solar photons. Their simple architecture, consisting of a thin sheet of semitransparent material doped with luminescent species (luminophore) and serving as a light guide, makes them a promising technology for mass production [1]. The operating principle of LSC, first introduced in 1976, is simple: the device contains luminophores that can absorb both direct and indirect sunlight1 and re-emit it as lower energy photons via a photoluminescence process. The photons are then light-guided to the edges of the device, where mounted PV cells convert the light into electricity.[2] In typical applications, the luminophores are randomly distributed in a polymer matrix in the form of a thin- film or a bulk rectangular slab. Although this constitutes rather than a simple and inexpensive method to fabricate an LSC, the random distribution can promote aggregation of the luminophores, leading to LSC efficiency losses due to quenching and reabsorption phenomena.

An interesting approach, explored in this work is to incorporate luminophore moieties with a monomeric functionality (e.g. methacrylate) into the polymer chain by direct copolymerization. To simultaneously broaden the absorption spectrum of the LSC device and reduce its self-absorption, we used two luminophores with different absorption and emission spectra for efficient Förster resonance energy transfer (FRET). FRET is an efficient means for spectral management: with suitable luminophores, energy can be transferred from the blue end of the visible spectrum to the red region. [3]

The donor-acceptor pair (D-A) was carefully chosen to promote FRET phenomena between luminophores. In this work, we investigated the photophysical properties and LSC performance of the donor-acceptor pair of 7-(2-hydroxyethoxy)-4-methylcoumarin (HEOMC) and mono- OH 1,6,7,12-tetra(phenoxy)-perylene diimide (OH -tpPDI). Coumarin was selected as the donor molecule and perylene diimide molecule (OH -tpPDI) as the emitter molecule. Subsequently mono- OH D-E luminophores were end-capped with 2-isocyanatoethyl methacrylate via a poly-urethanization reaction to obtain methacrylic monomers of coumarin methacrylate (CMA) and perylene methacrylate (PMA), accordingly. Consequently, polymeric host matrices comprise polymethyl methacrylate MMA, CMA and PMA monomers from a free- radical random polymerization at various concentrations, with MMA serving the role of a spacer in the FRET system.