Using TD-DFT, we performed simulations of the adiabatic energies of 40 fluorescent molecules for which the experimental 0-0 energies in condensed phase are available. We used six hybrid functionals (B3LYP, PBE0, M06, M06-2X, CAM-B3LYP, and LC-PBE) that have been shown to provide accurate transition energies in previous TD-DFT assessments, selected two diffuse-containing basis sets, and applied the most recent models for estimating bulk solvation effects. In each case, the correction arising from the difference of zero-point vibrational energies between the ground and the excited states has been consistently determined. Basis set effects have also been carefully studied. It turned out that PBE0 and M06 are the most effective functionals in terms of average deviation (mean absolute error of 0.22-0.23 eV). However, both the M06-2X global hybrid that contains more exact exchange and the CAM-B3LYP range-separated hybrid significantly improve the consistency of the prediction for a relatively negligible degradation of the average error. In addition, we assessed (1) the cross-structure/spectra relationships, (2) the importance of solvent effects, and (3) the differences between adiabatic and vertical energies.

The band shapes corresponding to both the absorption and emission spectra of a set of 20 representative conjugated molecules, including recently synthesized structures, have been simulated with a Time-Dependent Density Functional Theory model including diffuse atomic orbitals and accounting for bulk solvent effects. Six hybrid functionals, including two range-separated hybrids (B3LYP, PBE0, M06, M06-2X, CAM-B3LYP, and LC-PBE) have been assessed in light of the experimental band shapes obtained for these conjugated compounds. Basis set and integration grid effects have also been evaluated. It turned out that all tested functionals but LC-PBE reproduce the main experimental features for both absorption and fluorescence, though the average errors are significantly larger for the latter phenomena. No single functional stands out as the most accurate for all aspects, but B3LYP yields the smallest mean absolute deviation. On the other hand, M06-2X could be a valuable compromise for excited-states as it reproduces the 0-0 energies and also gives reasonable band shapes. The typical mean absolute deviations between the relative positions of the experimental and theoretical peaks in the vibrationally resolved spectra are ca. 100 cm(-1) for absorption and 250 cm(-1) for emission. In the same time, the relative intensities of the different maxima are reproduced by TD-DFT with a ca. 10-15% accuracy.

Using a set of 40 conjugated molecules, we assess the performance of an "optimally tuned" range-separated hybrid functional in reproducing the experimental 0-0 energies. The selected protocol accounts for the impact of solvation using a corrected linear-response continuum approach and vibrational corrections through calculations of the zero-point energies of both ground and excited-states and provides basis set converged data thanks to the systematic use of diffuse-containing atomic basis sets at all computational steps. It turns out that an optimally tuned long-range corrected hybrid form of the Perdew-Burke-Ernzerhof functional, LC-PBE*, delivers both the smallest mean absolute error (0.20 eV) and standard deviation (0.15 eV) of all tested approaches, while the obtained correlation (0.93) is large but remains slightly smaller than its M06-2X counterpart (0.95). In addition, the efficiency of two other recently developed exchange-correlation functionals, namely SOGGA11-X and ωB97X-D, has been determined in order to allow more complete comparisons with previously published data.

Vibrationally resolved absorption spectra of a series of anthraquinoidic dyes have been obtained with a polarizable continuum model time-dependent density functional theory approach. Firstly, we assessed the impact of the atomic basis set on both the transition energies and the vibronic shapes of 1,4-NH2-anthraquinone using a large panel of Pople's basis sets, up to the 6-311++G(3df,3pd). In a second stage, an extensive functional benchmark has been performed to determine an adequate approach for the same compound. In the third step, a complete analysis of the origin of the band shape was performed for the same derivative. In the fourth stage, a set of functionals has been applied to investigate the position isomers in the dihydroxy anthraquinone series. Finally, in a last phase, the methodology has been used for three dyes of technological interest. It turns out that the chosen basis set has a relatively limited impact on the computed transition energies as well as the topology of the vibronic shape, but both are significantly influenced by the selected functional. In the present case, no single functional simultaneously provides highly accurate positions and intensities of the different bands, but ωB97XD appears to be a good compromise. This analysis allows to rationalize the difference in shapes experimentally noticed for the visible band of apparently similar anthraquinones.

The solvent polarity parameter E T (30) is newly measured from the solvatochromism of the betaine dye 30 for 84 solvents and re-measured for 186 additional ones. The results are organized in a database. It is shown that the validity of linear solvation energy relationships used for the determination of secondary E T (30) values is limited to non-hydrogen-bond donor solvents. Relationships with the chain length n are given for the determination of tertiary E T (30) values of the homologous H(CH 2 ) n Y solvent series. The parameter E T (30) is orthogonal to the function of the refractive index (n 2 À 1) / (2n 2 + 1). For non hydrogen-bond donor solvents, this allows to enter E T (30) as an almost pure electrostatic parameter in a new linear solvation energy relationship.

Record photoconversion efficiency was achieved in DSC with stable heteroleptic bisdiimine complexes prepared by HETPHEN strategy.

We report here the synthesis and full chemical and physical characterizations of the first stable heteroleptic copper(I)-bis(diimine) complexes designed for implementation in dye sensitized solar cells (DSC). Thanks to the HETPHEN concept, pure and stable heteroleptic copper(I) complexes were isolated. Anchorage of the sensitizers was provided by 2,2'-biquinoline-4,4'-dicarboxylic acid (dcbqH2), while sterically challenged ligands 2,9-dimesityl-1,10-phenanthroline (L0) and N-hexyl-2,9-dimesityl-1,10-phenanthroline-[a:b]imidazo-(4'-dianisylaminophenyl) (L1) were used to complete the copper(I) coordination sphere. The resulting heteroleptic complexes C1 and C2 exhibit a broad MLCT transition spreading over a wide wavelength domain, especially when adsorbed onto nanoparticulate TiO2 photoanodes, providing a rather comprehensive visible light collection. The corresponding DSC were evaluated under AM 1.5 simulated solar light and rather weak performances were obtained owing to small J(sc) and V(oc). This is due to a combination of low extinction coefficient and poor driving forces for the various interfacial processes. However, significant improvements in the performances were monitored upon ageing in the dark, likely due to beneficial reorganization of the dye monolayers. The possibility to isolate stable asymmetric systems paves the way for structurally assisted photo-induced charge injection from the chemisorbed copper(i) based sensitizers into the conduction band of TiO2, through charge vectorialization.

In this study, four new diketopyrrolopyrrole (DPP) sensitizers, with a dicarboxylated triphenylamine anchoring group for attachment to NiO, were prepared and their electronic absorption, emission and electrochemical properties were recorded. The nature of the electronic excited-states was also modeled with Time-Dependent Density Functional Theory (TD-DFT) quantum chemistry calculations. The photovoltaic performances of these new dyes were characterized in NiO-based dye-sensitized solar cells (DSCs) with the classical iodide/triiodide and cobalt­(II/III)–polypyridine electrolytes, in which they proved to be quite active. Laser spectroscopy on dye/NiO/electrolyte films gave evidence for ultrafast hole injection into NiO (0.2–10 ps time scales). For the dyes with an appended naphtalenediimide (NDI) acceptor unit, ultrafast electron transfer to the NDI dramatically prolonged the lifetime of the charge separated state NiO+/dye–, from the ps time scale to an average lifetime ≈0.25 ms, which is among the slowest charge recombinations ever reported for dye/NiO systems. This allowed for efficient regeneration by CoIII–polypyridine electrolytes, which translated into much improved PV-performance compared to the DPP dyes without appended NDI. Overall, these results underscore the suitability of DPP as sensitizers for NiO-based photoelectrochemical devices for photovoltaic and photocatalysis.