Investigation of sensitizer adsorption and the influence of protons on current and voltage of a dye-sensitized nanocrystalline TiO2 solar cell

FTIR spectra of [Ru(dcbpyH(2))(2)(NCS)(2)] (N3), (BU4N)(2)[Ru(dcbpyH)(2)(NCS)(2)] (N719), and (Bu4N)(4)[Ru(dcbpY)(2)(NCS)(2)] (N712) complexes measured as solid samples in photoacoustic mode display fine resolution of IR bands and exhibit differences between the cis and the trans carboxylic acid groups. The interaction between N3, N719, and N712 sensitizers with nanocrystalline TiO2 film was investigated by ATR-FTIR spectroscopy. The data show that these complexes are being anchored onto the TiO2 surface in bridging coordination mode using two out of their four carboxylic acid groups, which are trans to the NCS ligand. The effect of protons on both the short circuit photocurrent and the open circuit photovoltage of dye-sensitized nanocrystalline solar cells was scrutinized. For the standard electrolyte formulation employed and TiCl4 treated mesoporous TiO2 films, the monoprotonated form of the N3 dye exhibited superior power conversion efficiency under AM 1.5 sun compared to the four, two, and zero proton sensitizers.