Pentafluorosulfanyl-functionalised BODIPY push-pull dyes for p-type dye-sensitized solar cells.

We report a push-pull BODIPY-based dye functionalised with an electronegative SF group at the position for applications in photocathodes in tandem dye-sensitized solar cells (DSSCs). The push-pull character enhances charge-transfer from the mesoporous NiO cathode surface towards the redox mediator. A Knoevenagel condensation reaction was used to introduce the carboxylic acid to anchor the dye to the oxide surface, a styryl linker which increases the conjugation in the molecule and shifts the absorption to the red.

A BF Chelate Exhibiting Excimer-like Fluorescence with an Unusually Large Stokes Shift in the Crystalline Phase.

The target mono-BF complex is weakly emissive in fluid solution because radiationless decay of the excited-singlet state is promoted through an intramolecular N⋅⋅⋅H-N hydrogen bond. The lack of mirror symmetry for this compound is attributed to vibronic effects, as reported previously for the bis-BF complex (BOPHY). Red-shifted fluorescence is observed from single crystals, the emission quantum yield approaching 30 % with a fluorescence lifetime of 2 ns.

Optical spectroscopic properties recorded for simple BOPHY dyes in condensed media: The mirror-symmetry factor.

The BOPHY structural scaffold provides opportunities for the synthesis of innumerable derivatives with linear geometries and well-controlled π-conjugation pathways. The simpler BOPHY chromophores are highly fluorescent but exhibit poor mirror symmetry between absorption and fluorescence spectra at ambient temperature. In particular, the absorption (and excitation) spectra are broad and appear as two overlapping bands of comparable intensity.

Photocatalysis and self-catalyzed photobleaching with covalently-linked chromophore-quencher conjugates built around BOPHY.

Two Chromophore-Quencher Conjugates (CQCs) have been synthesized by covalent attachment of the anti-oxidant dibutylated-hydroxytoluene (BHT) to a pyrrole-BF2 chromophore (BOPHY) in an effort to protect the latter against photofading. In fluid solution, light-induced intramolecular charge transfer is favoured in polar solvents and helps to inhibit photo-bleaching of the chromophore. The rate of photo-fading, which scales with the number of BHT residues, is zero-order in polar solvents but shows a linear dependence on the number of absorbed photons.

Effects of Temperature and Concentration on the Rate of Photobleaching of Erythrosine in Water.

Erythrosine, a popular food dye, undergoes fast O-sensitive bleaching in water when subjected to visible light illumination. In dilute solution, erythrosine undergoes photobleaching via first-order kinetics, where the rate of bleaching depends critically on the rate of photon absorption and on the concentration of dissolved oxygen. Kinetic studies indicate that this inherent bleaching is augmented by self-catalysis at higher concentrations of erythrosine and on long exposure times.