Diastereoisomers of Ruthenium Dyes with Unsymmetric Ligands for DSC: Fundamental Chemistry and Photovoltaic Performance.

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.