Resonance Raman spectra are reported for Ru(4,4'-dicarboxylic acid-2,2'-bipyridine)2(NCS)2 (commonly called "N3") in ethanol solution and adsorbed on nanoparticulate colloidal TiO2 in ethanol (EtOH) and in acetonitrile (ACN), at wavelengths within the visible absorption band of the dye. Raman cross sections of free N3 in EtOH are found to be similar to those of N3 adsorbed on colloidal TiO2 in EtOH, and are generally lower than those of N3 on TiO2 in ACN. Strong electronic coupling mediated by surface states results in red-shifted absorption spectra and enhanced Raman signals for N3 adsorbed on nanocolloidal TiO2 in ACN compared to EtOH. In contrast, the absorption spectrum of N3 on nanocrystalline TiO2 in contact with solvent is similar for ACN and EtOH. Wavelength-dependent depolarization ratios for N3 Raman bands of both free and adsorbed N3 reveal resonance enhancement via two or more excited electronic states. Luminescence spectra of N3 adsorbed on nanocrystalline films of TiO2 and ZrO2 in contact with solvent reveal that the quantum yield of electron injection phi(ET) into TiO2 decreases in the order ACN > EtOH > DMSO. Dye-sensitized solar cells were fabricated with N3 adsorbed on nanocrystalline films of TiO2 in contact with ACN, EtOH, and DMSO solutions containing LiI/LiI3 electrolyte. Photoconversion efficiencies eta were found to be 2.6% in ACN, 1.3% in DMSO, and 0.84% in EtOH. Higher short circuit currents are found in cells using ACN, while the maximum voltage is found to be largest in DMSO. It is concluded that the increased photocurrent and quantum yield of interfacial electron transfer in acetonitrile as compared to ethanol and DMSO is primarily the result of faster electron injection of N3 when adsorbed on TiO2 in the presence of ACN as opposed to EtOH or DMSO.
"Another possible reason for the decreased JSC values is the added ethanol from dye solution in the electrolyte. According to a previous research, the rate of electron injection from the dye to the TiO2 film was more rapid in acetonitrile than ethanol21. This was because the O atom in ethanol had a stronger attraction to the functional group of the dye than the N atom in acetonitrile22. "
[Show abstract][Hide abstract] ABSTRACT: The widespread commercialization of dye-sensitized solar cells remains limited because of the poor long-term stability. We report on the influence of dye-molecules added in liquid electrolyte on long-term stability of dye-sensitized solar cells. Dye-desorption from the TiO2 surface during long-term cycling is one of the decisive factors that degrade photocurrent densities of devices which in turn determine the efficiencies of the devices. For the first time, desorption of dye from the TiO2 surface could be suppressed by controlling thermodynamic equilibrium; by addition of dye molecules in the electrolyte. The dye molecules in the electrolyte can suppress the driving forces for the adsorbed dye molecules to be desorbed from TiO2 nanoparticles. As a result, highly enhanced device stabilities were achieved due to the reduction of dye-desorption although there was a little decrease in the initial efficiencies.
[Show abstract][Hide abstract] ABSTRACT: Chemical fixing of xanthene dye (eosin Y) on the surface of TiO2 electrode was carried out by modifying the electrode with silane-coupling reagent to obtain stable dye-sensitized TiO2 electrode. Such silane modification can not only evidently enhance the stability of dye-sensitized TiO2 electrode but also improve the energy conversion efficiency of the assembled cells by increasing short-circuit photocurrent
SC) and open-circuit photovoltage (V
OC). It was found that the improvements of cell performances differ depending on the composition of the electrolyte. The optimum
cell of the cell performance was achieved in the electrolyte with 0.5 mol/L TBAI/0.05 mol/L I2/EC:PC(3:1 w/w), yielding J
SC of 4.69 mA·cm−2, V
OC of 0.595 V, fill factor (FF) of 0.64 and η of 1.78%. Different spectroscopic techniques including UV-Vis spectra, fluorescence
spectra, EIS and dark current measurements were employed to derive reasonable analysis and explanations.
Chinese Science Bulletin 08/2009; 54(15):2633-2640. DOI:10.1007/s11434-009-0440-8 · 1.58 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The lowest energy transition of [Ru(CN)(4)(ppb)](2-) (ppb = dipyrido[2,3-a:3',2'-c]phenazine), a metal-to-ligand charge transfer, has been probed using resonance Raman spectroscopy with excitation wavelengths (488, 514, 530, and 568 nm) spanning the lowest energy absorption band centered at 522 nm. Wave packet modeling was used to simultaneously model this lowest energy absorption band and the cross sections of the resonance Raman bands at the series of excitation wavelengths across this absorption band. A fit to within +/-20% was obtained for the Raman cross sections, close to the experimental uncertainty which is typically 10-20%. Delta values of 0.1-0.4 were obtained for modes which were either localized on the ppb ligand (345-1599 cm(-1)) or the CN modes (2063 and 2097 cm(-1)). DFT calculations reveal that the resonance Raman bands observed are due to modes delocalized over the entire ppb ligand.
The Journal of Physical Chemistry A 10/2006; 110(38):11194-9. DOI:10.1021/jp063197b · 2.69 Impact Factor
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.