Design and Characterization of Heteroleptic Ruthenium Complexes Containing Benzimidazole Ligands for Dye-Sensitized Solar Cells: The Effect of Fluorine Substituents on Photovoltaic Performance.
We designed heteroleptic ruthenium complexes (RD12-RD15) containing fluoro-substituted benzimidazole ligands for dye-sensitized solar cells (DSSCs). These dyes were synthesized according to a typical one-pot procedure with the corresponding ancillary ligands produced in two simple steps; they were prepared into DSSC devices according to the same conditions of fabrication. The eventual devices show a systematic trend of increasing VOC and decreasing JSC with fluorine atoms of increasing number substituted on the ligand. The charge-extraction results show that upward shifts of the TiO2 potential occurred when the fluoro-substituted dyes were sensitized on TiO2 with a systematic trend of shift N719 > RD15 (with 5 F) > RD12 (with 2 F) >RD5 (no F); the intensity-modulated photovoltage spectra indicate that those fluoro substituents retard charge recombination with the electron lifetimes (τR) in the order RD15 > RD12 > RD5 > N719, consistent with the variation of VOC for the systems.
Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Hsinchu 30010, Taiwan.
Wei-Kai
WK
Huang
Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Hsinchu 30010, Taiwan.
Hui-Ping
HP
Wu
Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Hsinchu 30010, Taiwan.
Pi-Lun
PL
Lin
Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Hsinchu 30010, Taiwan.
Yuan-Pern
YP
Lee
Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Hsinchu 30010, Taiwan.
Eric Wei-Guang
EW
Diau
IMVS; bezimidazole; charge extraction; charge recombination; dye-sensitized solar cell; heteroleptic Ru dye; impedance spectroscopy