| Summary: | 碩士 === 國立交通大學 === 應用化學研究所 === 98 === Novel Ruthenium complexes (SW dyes), which contain the carbazole, phenothiazine or benzothiophene as a secondary electron donor moiety, were designed and synthesized for dye-sensitized solar cell (DSSC) applications. The general formula for the target sensitizes is expressed as [Ru(dcbpy)(L)(NCS)2] where dcbpy represents 4,4’-dicarboxylic acid-2,2’-bipyridine and L represents 4,4’-bis[(E)-2-(N-ethylcarbazole-3-yl)-vinyl]2,2’-bipy-
ridine (SW1), 4,4’-bis[(E)-2-(N-hexylcarbazole-3-yl)vinyl]2,2’-bipyridine (SW2), 4,4’-bis-
{(E)-2-[N-(4-hexyloxyphenyl)carbazole-3-yl]vinyl}2,2’-bipyridine (SW3), 4,4’-Bis{(E)-2-
[(N-hexylcarbazol-3-yl)thiophen-5-yl]-vinyl}2,2’-bipyridine (SW4), 4,4’-Bis-[(E)-2-(N-
ethylphenothiazin-3-yl)vinyl]2,2’-bipyridine (SW5), or 4,4'-Bis-[(E)-2-(benzo[b]thiophene-3-yl)vinyl]2,2'-bipyridine (SW6). These complexes were synthesized via a typical one-pot procedure and identified with NMR, EA and Mass measurements. The corresponding DSSC devices were characterized based on steady-state spectral, IV/IPCE, and CV/EIS measurements. The design of SW1 containing the carbazole group extends the conjugation of the bipyridine ancillary ligand and increases remarkably the absorption coefficient for the improved light-harvesting ability. This spectral feature enables us to fabricate a new generation DSSC device with a much thinner TiO2 film (7.6 ?慆). In addition, we have designed two dyes (SW2, SW3) with a structure similar to SW1 but containing hydrophobic groups to retard the electron interception with I3- and increase the stability of the devices. Moreover, we found that the new dyes (SW4, SW6) with increased conjugation length would extend the absorption spectra toward longer wavelengths, but at the same time they suffered poor solubility to give the low amounts of dye loading. Finally, the ligand with another hole transport functional group was designed to make a new Ru dye (SW5) with increased charge separation to enhance the VOC. Among these new Ru dyes, the best device performance results from SW1, which gives power conversion efficiency ~7 %.
In addition, we synthesized the known dye HRS-12 and Z907 with symmetric ancillary ligand. Furthermore, we also synthesized the known dye HRS-9 and the novel dye Z907-1 [Ru(dcbpy)(4-methyl-4’-nonyl-2,2’-bipyridine)(NCS)2] with asymmetric ancillary ligand. We find that the asymmetric dyes improve JSC than the symmetric dyes due to higher dye-loading. In the other case, dyes with heterocyclic group (HRS-9) may induce energy loss in the electron transfer process due to the intermolecular aggregation result in decreasing JSC.
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