Browsing by Author "Lin, Pi-Lun"

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Design and Characterization of Heteroleptic Ruthenium Complexes Containing Benzimidazole Ligands for Dye-Sensitized Solar Cells: The Effect of Fluorine Substituents on Photovoltaic Performance
(1970-01-01)
Huang, Wei-Kai
;
Wu, Hui-Ping
;
Lin, Pi-Lun
;
Lee, Yuan-Pern
;
Diau, Eric Wei-Guang
"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 V-OC and decreasing J(SC) 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 (tau(R)) in the order RD15 > RD12 > RD5 > N719, consistent with the variation of V-OC for the systems."
Design and Characterization of Heteroleptic Ruthenium Complexes Containing Benzimidazole Ligands for Dye-Sensitized Solar Cells: The Effect of Thiophene and Alkyl Substituents on Photovoltaic Performance
(2013-02-07)
Huang, Wei-Kai
;
Wu, Hui-Ping
;
Lin, Pi-Lun
;
Diau, Eric Wei-Guang
;
應用化學系
We designed heteroleptic ruthenium complexes RD16-RD18 containing fluoro-substituted and thiophene-based benzimidazole ligands for dye-sensitized solar cells. Whereas the substitution of only fluorine in the RD12 device has an effect of enhancing the open-circuit voltage (V-OC), additional substitution of thiophene in the RD16-RD18 sensitizers showed a slightly decreased V-OC. Systematic enhanced short-circuit current density (J(SC)) and efficiency (eta) of power conversion of the devices had the order RD18 > RD17 > RD16 > RD12 > N719, attributed to the increasing light-harvesting ability and the broadened spectral features with thiophene-based ligands. Measurements of charge extraction and intensity-modulated photovoltage spectra indicate that thiophene substitution shifts downward the TiO2 potential and accelerates charge recombination, but inclusion of a long hexyl chain on the thiophene moiety retards charge recombination to account for the variation of V-OC in the series. For a duration test of device performance at ambient temperature, only similar to 2% degradation of cell performance was found for the devices of RD18 and RD12 over 2000 h, but a 10% decrease in overall efficiency was observed in the N719 device.