| Summary: | 博士 === 國立交通大學 === 材料科學與工程學系 === 99 === A series of seven new ruthenium photosensitizers, [Ru(dcbpy)(opip)(NCS)2] (JF-1, dcbpy = 4,4'-dicarboxylic acid-2,2'-bipyridine, opip = 2-(4-octylphenyl)-1H-imidazo [4,5-f][1,10]phenanthroline), [Ru(dcbpy)(otip)(NCS)2] (JF-2, otip = 2-(5-octylthiophen-2-yl)-1H-imidazo[4,5-f][1,10]phenanthroline), [Ru(dcbpy)(potip)(NCS)2] (JF-3, potip = 2-(4-(10H-phenothiazin-10-yl)-5-octyl- thiophen-2-yl)-1H-imidazo[4,5-f][1,10]phenanthroline), [Ru(dcbpy)(dpotip)(NCS)2] (JF-4, dpotip = 2-(4-(N,N-diphenylamino)-5-octylthiophen-2-yl)-1H-imidazo[4,5-f] [1,10]phenanthroline), [Ru(dcbpy)(obtip)(NCS)2] (JF-5, obtip = 2-(5-octyl-(2,2'- bithiophen)-5'-yl)-1H-imidazo[4,5-f][1,10]phenanthroline), [Ru(dcbpy)(ottip)(NCS)2] (JF-6, ottip = 2-(5-octyl-2,2',5',2''-terthiophene-5''-yl)-1H-imidazo[4,5-f][1,10] phenanthroline) and [Ru(dcbpy)(dottip)(NCS)2] (JF-7, dottip = 2-(2,3-di- (5-octylthiophen-2-yl)thiophen-5-yl)-1H-imidazo[4,5-f][1,10]phenanthroline), were designed and synthesized in a typical one-pot reaction. The power-conversion efficiency of JF-2 was 20% higher than that of JF-1, due to modification of the ancillary ligand with a thiophene moiety. The greater device performance of JF-2 compared to JF-1 was caused from the broader MLCT distribution, the appropriate localization of the frontier orbitals and the stronger driving force of the charge injection and regeneration. The multifunctionalized ruthenium dye JF-3 incorporating an excellent electron-donating phenothiazine shows the superior DSCs performance (9.1%) compared to N3 (8.8%) and JF-4 (7.9%). The comparison of electron-donating phenothiazine and N,N-diphenylamino groups utilized in multifunctionalized molecular architecture for ruthenium dyes demonstrated that the phenothiazine group can efficiently increase and broaden the molar extinction coefficient of band II in the UV?{vis absorption spectrum, reduce the device resistances, rise the electron lifetime, and enhance the power-conversion efficiency. The ruthenium sensitizer JF-5 incorporating a linear and planar 2,2'-bithiophene antenna showed the best DSCs performance (9.5%) compared to N3 (8.8%), JF-6 (8.7%), and JF-7 (6.4%). The difference in the performance of these sensitizers demonstrated that elongating the linear and planar light-harvesting antenna results in an enhancement in MLCT intensity, but a reduction in the quantity of dye-loading.
The findings in the structural comparision of these ruthenium photosensitizers, JF-1?{7, not only open an alternative strategy for the design of sophisticated 1,10-phenanthroline-based ligands and multifunctionalized ancillary ligands for improving the photovoltaic performance of ruthenium sensitizers, but also optimize light-harvesting antennas and point to a promising direction for molecule engineering in DSCs.
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