New tunable ruthenium complex dyes for TiO2 solar cells

• Ruthenium dyes with photoinjection tuned by ligand protonation/deprotonation.
• Novel ruthenium dyes with photoinjection from LMCT excited state.
• First mononuclear ruthenium tmt complex and properties.
• Ruthenium dyes with normalized efficiencies comparable to N719.
• Insights on the design of new ruthenium polypyridine dyes.

The light-to-electricity conversion efficiencies of the new (Bu4N)3[Ru(dcbpy)2(tmtH2)], (Bu4N)4[Ru(dcbpy)2(tmtH)] and (Bu4N)5[Ru(dcbpy)2(tmt)] complexes, where dcbpy = 2,2′-bipyridyl-4,4′-dicarboxylate and tmt = 2,4,6-trimercapto-1,3,5-triazine, were comparable with those obtained with the N719 dye. Furthermore, the contribution of two MLCT and a LMCT charge-transfer band to the energy conversion process was revealed by deconvolution of the photoaction spectra, indicating that they are the first ruthenium dyes presenting long distance photo-injection from a ligand-to-metal charge-transfer excited state.

Ruthenium complex dyes, whose photoinduced electron injection take place from MLCT and LMCT excited states and can be tuned by protonation/deprotonation of a bidentated trimercaptotriazine ligand, were isolated as solids, characterized and used for the preparation of solar cells. The surface concentration normalized conversion efficiencies were comparable with N719.Figure optionsDownload as PowerPoint slide