title: Diastereoisomers of Ruthenium Dyes with Unsymmetric Ligands for DSC: Fundamental Chemistry and Photovoltaic Performance.
abstract: A new thiocyanic acid-free ruthenium sensitizer, CYC-B29, containing two unsymmetrical ancillary ligands, was synthesized, and its three diastereoisomers CYC-B29-CC, CYC-B29-TT, and CYC-B29-CT with significantly different optical, electronic, and electrochemical properties were carefully separated. CYC-B29-TT with the smallest size has the strongest absorption coefficient of the MLCT band, the shortest λmax, the lowest highest occupied molecular orbital level and the highest dye loading. Therefore, dye-sensitized solar cell based on CYC-B29-TT has the highest efficiency, which is two times higher than that of CYC-B29-CC-sensitized device and 10% higher than that of N719-based cell. Time-dependent density functional theory-calculated transition bands for the three isomers are not identical, and only CYC-B29-TT has the calculated transition bands close to the experimental absorption profile. Although the calculated transition bands for CYC-B29-CC and CYC-B29-CT are not consistent with the experimental data, the ground-state vertical excitation energy with oscillator strength and electron-density difference map data combining with the dye loading predict correctly the order of the photocurrent for the three isomers sensitized devices.
authors.affiliation: Department of Chemistry and ‡Research Center for New Generation Photovoltaics, National Central University , Jhong-Li 32001, Taiwan, ROC.
authors.forename: Jheng-Ying
authors.initials: JY
authors.lastname: Li
authors.affiliation: Department of Chemistry and ‡Research Center for New Generation Photovoltaics, National Central University , Jhong-Li 32001, Taiwan, ROC.
authors.forename: Chia
authors.initials: C
authors.lastname: Lee
authors.affiliation: Department of Chemistry and ‡Research Center for New Generation Photovoltaics, National Central University , Jhong-Li 32001, Taiwan, ROC.
authors.forename: Chia-Yuan
authors.initials: CY
authors.lastname: Chen
authors.affiliation: Department of Chemistry and ‡Research Center for New Generation Photovoltaics, National Central University , Jhong-Li 32001, Taiwan, ROC.
authors.forename: Wen-Long
authors.initials: WL
authors.lastname: Lee
authors.affiliation: Department of Chemistry and ‡Research Center for New Generation Photovoltaics, National Central University , Jhong-Li 32001, Taiwan, ROC.
authors.forename: Ren
authors.initials: R
authors.lastname: Ma
authors.affiliation: Department of Chemistry and ‡Research Center for New Generation Photovoltaics, National Central University , Jhong-Li 32001, Taiwan, ROC.
authors.forename: Chun-Guey
authors.initials: CG
authors.lastname: Wu