Solar collectors based on luminescent 2,5-diarylimidazoles

We report on the synthesis of new fluorescent symmetrical 2,5-diaryl-1-methylimidazoles obtained in good yields by using direct C-H arylation synthetic strategies. Spectroscopic investigations in THF solution evidenced that the 2,5-diarylimidazole bearing the strong electron-withdrawing cyanoacrylate groups achieved the best trade-off between fluorescence maximum (518 nm), Stokes shift (115 nm) and a quantum yield of 25%. Highly homogeneous dispersions of the selected fluorophore in poly(methyl methacrylate) (PMMA) thin films (25 ± 5 μm of thickness) perfectly maintained the optical features in solution, thus providing a brilliant green emission and a markedly enhanced quantum yield of 55%. Photocurrent measurements of the PMMA collectors supported the use of 2,5-diaryl-1-methylimidazoles as accessible alternatives to perylene backbones for the development of LSC with optical efficiencies close to 7%.