Paolo Salvatori

Thiocyanate-Free Ruthenium(II) Sensitizer with a Pyrid-2-yltetrazolate Ligand for Dye-Sensitized Solar Cells

The synthesis of the new complex [Ru(Tetrazpy)(dcbpy)2]Cl is reported, along with its spectroscopical, electrochemical, and theoretical characterization. The first dye-sensitized solar cell device with this complex has been prepared, leading to a 3% of conversion efficiency, promising data considering the simplicity of the Tetrazpy ligand.

Bistriphenylamine-based organic sensitizers with high molar extinction coefficients for dye-sensitized solar cells

A series of novel bistriphenylamine-based organic sensitizers (coded as RC-dyes) with high molar extinction coefficients (.5.0 6 10 4 M 21 cm 21 ) have been synthesized for dye-sensitized solar cells (DSSCs). By changing the length of the p-conjugation bridge thiophene from zero to two between the donor and the acceptor part, the range of absorption and its corresponding photon-to-current conversion was modulated gradually to the low energy region in the visible spectrum. Based on the electrochemical and theoretical investigations on the electronic and geometrical structure, RC dyes were shown to be a promising candidate for efficient metal-free organic sensitizers with strong light absorption. Among RC dyes (11y13) tested, the highest power conversion efficiency of 5.67% was obtained from RC-13 with a short circuit current of 10.78 mA cm 22 , an open circuit voltage of 0.71 V, and a fill factor of 0.74 under standard AM 1.5 measurement conditions.

Carbazole-based sensitizers for potential application to dye sensitized solar cells

AbstractTwo push-pull molecules employing carbazole and alkyl thiophene (CAR-THIOHX) or carbazole and triphenylamine (CAR-TPA) as donor moieties, with the cyanoacrylic group as the acceptor, have been designed and synthesized by simple organic transformations. Photophysical and electrochemical studies revealed the potential of these two systems in dye sensitized solar cells (DSSC). Under standard irradiation conditions, CAR-TPA and CAR-THIOHX exhibited 2.12 and 1.83% of overall power conversion efficiencies respectively. The moderate photovoltaic efficiency of the sensitizers has been attributed to the poor light absorption of the sensitizers in the visible region. Density functional theory (DFT) calculations have shown a strong intramolecular charge transfer character, with the HOMOs of both the sensitizers exclusively localized on the corresponding donor moieties and LUMOs on the cyanoacrylic acid acceptor. On the other hand, the calculated high dihedral angle between the carbazole donor and the phenyl bridge for these sensitizers impedes the conjugation along the dyes backbone, and thus leads to less extended and intense absorption spectra in the visible region. Graphical AbstractTwo push-pull carbazole based molecules, CAR-THIOHX and CAR-TPA, have been designed and synthesized by simple organic transformations. Photophysical and electrochemical studies revealed the potential of these two molecules in dye sensitized solar cells (DSSC). Under standard irradiation conditions, CAR-TPA and CAR-THIOHX exhibited 2.12 and 1.83% of overall power conversion efficiencies, respectively.

Stability of ruthenium/organic dye co-sensitized solar cells: a joint experimental and computational investigation

We carried out a joint experimental and theoretical study of the stability of dye-sensitized solar cells using a mixture of black dye (N749) and a Y1 organic co-adsorbent. The aim of this work was to investigate the stability of these highly efficient sensitizers. The co-sensitized device showed remarkable stability under the conditions investigated (1100 h of about 1 Sun light soaking at 55 °C). The partial desorption of the organic co-adsorbent was identified as a possible cause of the slight reduction in the photocurrent value. Theoretical investigations on the dye-sensitized semiconductor surface using DFT methods showed a considerably lower adsorption energy for Y1 compared with N749, in particular upon oxidation, possibly leading to desorption of the dye under working conditions. The devices using only the Y1 organic dye consistently showed a considerably lower stability.