Berlinguette, Curtis PaulBomben, Paolo Giovanni2012-07-132012-11-132012-07-132012http://hdl.handle.net/11023/119A series of bidentate cyclometalated Ru(II) complexes of general formula [Ru(N^N)(N^N)(C^N)]+, where N^N = polypyridyl ligand and C^N = cyclometalating ligand, have been synthesized, characterized and tested in dye-sensitized solar cells (DSSCs). Cyclometalated Ru(II) complexes, in general, exhibited broader absorption profiles and cathodically shifted electrochemical potentials compared to their polypyridyl analogues. The prototypical cycloruthenated compound, [Ru(bpy)2(ppy)]+ (bpy = 2,2'-bipyridine; Hppy = 2-phenylpyridine), displayed comparable UV-vis spectral coverage to the standard DSSC dye, N3. Molar extinction coefficients were enhanced and the absorption profile was red-shifted through substitution of the molecular periphery. Molecules from the [Ru(bpy)2(ppy)]+ family displayed HOMO and excited-state energy levels properly aligned for use in the DSSC. Anchoring –CO2H groups were ideally located on the bidentate polypyridyl ligands (e.g., H2dcbpy; H2dcbpy = 4,4'-dicarboxy-2,2'-bipyridine) because this arrangement localized excited-state electron density proximate to TiO2. Increased molecular light absorption was accomplished by installing conjugated substituents (e.g., -NO2, -phenyl, -pyridyl, -2-thiophene-carbaldehyde) on the anionic ring of molecules with general formula [Ru(H2dcbpy)2(C^N)]+. Aromatic substituents were superior to –NO2 because of an ideally positioned lowest excited-state (i.e., localized to H2dcbpy instead of –NO2). Substitution of the anionic ring with 2-thiophene-5-carbaldehyde para to the Ru-C bond resulted in a superior absorption profile enabling a modest cell power conversion efficiency (PCE) of 3.3%. Replacement of one H2dcbpy ligand with bpy generated tris-heteroleptic cyclometalated Ru(II) dyes with general formula [Ru(H2dcbpy)(bpy)(C^N)]+. The use of electron-rich cyclometalating ligands, however, led to poor PCEs because of incompatible Ru electrochemical potentials for dye regeneration. Strong electron withdrawing groups (e.g., –CF3) were required on the C^N ligand to overcome this problem. The combination of electron-rich aromatic (e.g., thiophene, triarylamine) groups on the ancillary bpy and –CF3 groups on the C^N ligand enabled the best light-absorption properties of any dyes examined in this dissertation, while also maintaining properly aligned HOMO and excited-state energy levels for use in the DSSC. Power conversion efficiencies of 7.3% at 1 Sun were attained with these dyes, exceeding the 6.3% achieved by the paradigmatic N3 dye under the same conditions.engUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.Chemistry--InorganicSolarEnergyRutheniumDyesDSSCChromophoreCyclometalateddoctoral thesis10.11575/PRISM/25510