Green/Yellow-Emitting Conjugated Heterocyclic Fluorophores for Luminescent Solar Concentrators

In this study, we report on the synthesis of new organic fluorophores containing either the benzo[1,2-d:4,5-d]bisthiazole or the dithieno[3,2-b:2,3-d]silole heterocyclic unit, and on their application for the fabrication of luminescent solar concentrators (LSCs) made of poly(methyl methacrylate) (PMMA) thin films. In solution, the new compounds absorbed light in the visible region and displayed a brilliant green emission in the 500-600 nm range with moderate-to-good fluorescence quantum yields (0.25-0.68). Dispersions of selected fluorophores in PMMA thin films mostly maintained the light absorption features observed in solution, although in the case of benzobisthiazole-based fluorophore 1a an evident fluorescence red-shift was observed when increasing the compound concentration in the film. In agreement with its promising optical properties, LSCs prepared with the latter compound yielded interesting optical efficiencies up to 6.42%, not far from those of state-of-the-art PMMA LSC devices.