Inorganic Dyes


Due to the success of the N3, [Ru(4,4'-(COOH)2-bpy)(NCS)2], and its double protonated analogue, N719 as photo-sensitizers in DSC, most of the theoretical/computational investigations have been initially devoted to this complex. Our pioneering study in 2003 reported on the TDDFT absorption spectrum of the N3 dye in solution. The simulated absorption spectra was in very good agreement with the experiment and we evidenced the need to include the solvation effects to get accurate results, being able to quantitatively reproduce the solvatochromic shifts.



In order to improve the DSC efficiency, a series of new inorganic dyes have been scrutinized and tested. We investigated some of the most significant Ru(II)-dye sensitizers with direct application in DSC. Starting from the N3 or N719 homoleptic sensitisers, a major research line has been devoted to heteroleptic sensitizers, in which one of the equivalent two bipyridines of N3 is suitably functionalized obtaining N621, Z907, N945,  C101 and  Ru-EDOT.



The calculated absorption spectrum and the involved excited states of Ru-EDOT were perfectly consistent with the high experimental photovoltaic efficiencies. Indeed, the excitation at about 540 nm mainly leads to excited states localized onto the EDOT-substituted bipyridine. Since this heteroleptic sensitizer is adsorbed onto TiO2 via the carboxy-bipyridine ligand, the presence of lower lying excited states residing on such ligands allows efficient energy transfer to this state, and subsequent electron injection to TiO2. A similar electronic structure was calculated for the N945 complex, which exhibited an even higher molar extinction coefficient of 18.900 dm3 mol-1 cm-1, providing an increased photocurrent when applied in DSCs.



S. Fantacci, F. De Angelis, A. Selloni, J. Am. Chem. Soc. 2003, 125, 4381–4387.

De Angelis, F.; Fantacci, S.; Selloni, A. Selloni, Chem. Phys. Lett. 2004, 389, 204–208.

De Angelis, F.; Fantacci, S.; Selloni, A.; Nazeeruddin,   M. K. Chem. Phys. Lett. 2005, 415, 115–120.

Nazeeruddin, M. K.; De Angelis, F.; Fantacci, S.; Selloni, A.; Viscardi, G.; Liska, P.; Ito, S.; Bessho, T.; Graetzel, M. J. Am. Chem. Soc. 2005, 127, 16835–16847.

De Angelis, F.; Fantacci, S.; Selloni, A.; Nazeeruddin, M. K.; Graetzel, M. J. Am. Chem. Soc. 2007, 129, 14156-14157.

Abbotto, A.; Barolo, C.; Bellotto, L.; De Angelis, F.; Graetzel, M.; Manfredi, N.; Marinzi, C.; Fantacci, S.; Yum, J.-H.; Nazeeruddin, M. K.  Chem. Commun. 2008 5318-5320.