Luminescent Solar Concentrators Based on Energy Transfer from an Aggregation-Induced Emitter Conjugated Polymer
Luminescent solar concentrators (LSCs) are solar-harvesting devices fabricated from transparent waveguide that is doped or coated with lumophores. Despite their potential for architectural integration, the optical efficiency of LSCs is often limited by incomplete harvesting of solar radiation and aggregation-caused quenching (ACQ) of lumophores in the solid state. Here, we demonstrate a multi-lumophore LSC design which circumvents these challenges through a combination of non-radiative Förster energy transfer (FRET) and aggregation-induced emission (AIE). The LSC incorporates a green-emitting poly(tetraphenylethylene), p-O-TPE, as an energy donor and a red-emitting perylene bisimide molecular dye (PDI-Sil) as the energy acceptor, within an organic-inorganic hybrid di-ureasil waveguide. Steady-state photoluminescence studies demonstrate that the di-ureasil host induced AIE from the p-O-PTE donor polymer, leading to a high photoluminescence quantum yield (PLQY) of ~45% and a large Stokes shift of ~150 nm. Covalent grafting of the PDI-Sil acceptor to the siliceous domains of the di-ureasil waveguide also inhibits non-radiative losses by preventing molecular aggregation. Due to the excellent spectral overlap, FRET was shown to occur from p-O-TPE to PDI-Sil, which increased with acceptor concentration. As a result, the final LSC (4.5 cm x 4.5 cm x 0.3 cm) with an optimised donor- acceptor ratio (1:1 by wt%) exhibited an internal photon efficiency of 20%, demonstrating a viable design for LSCs utilising an AIE-based FRET approach to improve the solar-harvesting performance.