Photophysical properties of new p-phenylene- and benzodithiophene-based fluorophores for luminescent solar concentrators (LSCs)

Abstract

In this study, we report on the synthesis of new organic fluorophores containing either the pphenylene or the benzodithiophene cyclic nucleus connected to thiophene units via triple bonds and carbonyl group, and on their application for the fabrication of luminescent solar concentrators (LSCs). Their optical properties were evaluated. Independent of the core, dyes containing the COthiophene residues seem to be the most promising for LSCs applications. In fact, carbonyl groups only slightly lower quantum yield but significantly increase the red-shift so that the superimposition between the absorbance spectrum and the emission one is diminished. In the case of the benzodithiophene centre, light emission in the yellow-red portion of the spectrum is achieved. The latter dye is then selected for tests in a poly(methyl methacrylate) (PMMA) matrix. It showed good compatibility and homogenous distribution, no auto-absorption phenomena, and optical efficiencies of about 8% at 1 wt. %, i.e. comparable with those PMMA/Lumogen Red films in the same range of concentration.

Aggregation Modes of Chiral Diketopyrrolo[3,4‐c]pyrrole Dyes in Solution and Thin Films

“…The introduction of such lateral π‐conjugated units was performed in order to increase the self‐assembly of DPP dyes through intermolecular π‐stacking interactions between proximate molecules. The ( S )‐3,7‐dimethyl‐1‐octyl chain is a chiral moiety prepared from natural (−)‐β‐citronellol, [34] a compound occurring in Nature in rose oils and Pelargonium geranium ; [35] it is devoid of functionalities and it transfers its molecular asymmetry (stereogenic centre at position 3 of the aliphatic chain) to the entire system (chirality at supramolecular and mesoscopic scale) exclusively through dispersion forces and steric effects. On the other hand, we also designed the DPP dye 4 , which is instead characterized by two menthyl chiral units on the terminal positions of π‐conjugated backbone, attached to the thiophene rings of central DPP core through a π‐conjugated 4‐ethynylbenzoate linkage.…”

Luminescent solar concentrators with outstanding optical properties by employment of D–A–D quinoxaline fluorophores

“…Fluorescence quantum yields (Φf) in the solid state were determined by using a 152 mm diameter "Quanta-φ" integrating sphere, coated with Spectralon® and following the procedures reported earlier. 22,28,29 Epifluorescence microscopy was accomplished on a LED epifluorescence microscope (Schaefer South-East Europe S.r.l., Rovigo, Italy) equipped with a LED blue and green 5W light source and a DeltaPix Invenio 2EIII microscope camera (DeltaPix, Smorum, Denmark).…”

Luminescent Solar Concentrators from Waterborne Polymer Coatings

“…Fluorescence spectra were measured at room temperature with a Fluorolog ® -3 spectrofluorometer (Horiba Jobin-Yvon, Horiba Italy, Rome, Italy) equipped with a 450 W xenon arc lamp and double-grating excitation and single-grating emission monochromators. The emission quantum yields were determined by using a 152 mm diameter "Quanta-ϕ" integrating sphere, coated with Spectralon ® and following recently reported procedures [22,33,34].…”

“…All LSCs were obtained by casting the fluorophore-doped waterborne polymer dispersions over optically pure 50 × 50 × 3 mm 3 glass by varying the type of the emitter and its concentration (wt.%), while maintaining constant the film thickness at 100 µm. The performances were determined in terms of the optical efficiency (η) and discussed with those determined from PMMA-based LSC previously obtained with the same experimental setup [33,34].…”