Effect of Extended Conjugation of N-Heterocyclic Carbene-Based Sensitizers on the Performance of Dye-Sensitized Solar Cells.

We report the synthesis, characterization, and photovoltaic properties of four ruthenium complexes (CI101, CBTR, CB111, and CB108) having various N-heterocyclic carbene ancillary ligands, pyridine-imidazole, -benzimidazole, -dithienobenzimidazole, and -phenanthroimidazole, respectively. These complexes were designed to investigate the effect of extended conjugation ordained from ring fusion on the power conversion efficiencies of the solar cells. The device sensitized by CB108, the pyridine-phenanthroimidazole conjugated complex, showed an improved efficiency (9.