Akula Suri Babu, Chen Huei-Siou, Su Chaochin, Chen Bo-Ren, Chiou Jiunn-Jie, Shieh Chia-Hsuan, Lin Ya-Fen, Li Wen-Ren
Department of Chemistry, National Central University , Chungli, Taiwan 32001, ROC.
Institute of Organic and Polymeric Materials, National Taipei University of Technology , Taipei, Taiwan 10608, ROC.
Inorg Chem. 2017 Nov 6;56(21):12987-12995. doi: 10.1021/acs.inorgchem.7b01714. Epub 2017 Oct 11.
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 (9.89%) compared to those of pyridine-benzimidazole conjugated system (CBTR, 9.72%) and the parent unfused ring system (CI101, 6.24%). Surprisingly, the sulfur-incorporated pyridine-dithienobenzimidazole system (CB111, 9.24%) exhibited a little lower efficiency than that of N719 (9.41%). The enhanced photovoltaic performance of CB108 was mainly attributed to the increase in electron lifetime and diffusion length confirmed by the electrochemical impedance spectroscopy.
