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A novel Zn phthalocyanine-Zn porphyrin (ZnPc-ZnPor) dyad ( 1), in which a zinc porphyrin moiety is linked covalently with an ABAB-type zinc phthalocyanine moiety, has been designed and synthesized. The ZnPc-ZnPor dyad 1 can absorb over a wide spectral range of visible light. The fluorescence spectrum of dyad 1 revealed an intramolecular efficient energy transfer from Zn porphyrin to Zn phthalocyanine. When dyad 1 was used as a light-harvesting sensitizer for dye-sensitized solar cells, the cell sensitized by dyad 1 provided a power conversion efficiency of 2.7 % under simulated air mass 1.5 global sunlight. The incident photon-to-current efficiency spectrum of the dyad 1 cell suggested the contribution of both components in dyad 1 for the current generation. [ABSTRACT FROM AUTHOR]

A series of zinc phthalocyanine sensitizers ( PcS22- 24) having a pyridine anchoring group are designed and synthesized to investigate the structural dependence on performance in dye-sensitized solar cells. The pyridine-anchor zinc phthalocyanine sensitizer PcS23 shows 79 % incident-photon to current-conversion efficiency (IPCE) and 6.1 % energy conversion efficiency, which are comparable with similar phthalocyanine dyes having a carboxylic acid anchoring group. Based on DFT calculations, the high IPCE is attributed with the mixture of an excited-state molecular orbital of the sensitizer and the orbitals of TiO2. Between pyridine and carboxylic acid anchor dyes, opposite trends are observed in the linker-length dependence of the IPCE. The red-absorbing PcS23 is applied for co-sensitization with a carboxyl-anchor organic dye D131 that has a complementary spectral response. The site-selective adsorption of PcS23 and D131 on the TiO2 surface results in a panchromatic photocurrent response for the whole visible-light region of sun light. [ABSTRACT FROM AUTHOR]

A near-IR absorbing dye ( FcS1), in which three fluorene rings were fused with a porphyrazine ring, has been designed and synthesized as a photosensitizer for dye-sensitized solar cells (DSSCs). The fusion of the fluorene rings led to tailoring of the HOMO and LUMO energy levels as well as an expansion of the π-system. The absorption spectrum of FcS1 adsorbed onto a nanocrystalline TiO2 film suggested the formation of J-aggregates with tilted orientation of the macrocyclic ligands. While the power conversion efficiency of DSSCs sensitized with FcS1 was a modest 3.2 % under simulated air mass 1.5 global sunlight, FcS1 can convert the red and near-IR light regions between 600 and 860 nm into electricity. [ABSTRACT FROM AUTHOR]

A series of zinc-phthalocyanine sensitizers ( PcS16- 18) with different adsorption sites have been designed and synthesized in order to investigate the dependence of adsorption-site structures on the solar-cell performances in zinc-phthalocyanine based dye-sensitized solar cells. The change of adsorption site affected the electron injection efficiency from the photoexcited dye into the nanocrystalline TiO2 semiconductor, as monitored by picosecond time-resolved fluorescence spectroscopy. The zinc-phthalocyanine sensitizer PcS18, possessing one carboxylic acid directly attached to the ZnPc ring and six 2,6-diisopropylphenoxy units, showed a record power conversion efficiency value of 5.9 % when used as a light-harvesting dye on a TiO2 electrode under one simulated solar condition. [ABSTRACT FROM AUTHOR]

A series of panchromatic ruthenium sensitizers ( MJ sensitizers) with attached thiophene and phenyl units bearing alkyl chains was synthesized. A new synthetic route was used to examine all possible positions for the alkyl chains. The absorption spectra showed the sum of a ruthenium complex and peripheral organic chromophore units. The hypochromic effect and blueshift of the metal-to-ligand charge-transfer band observed in the modified ruthenium sensitizers were suppressed by changing the positions of the alkyl chains on the attached thiophene ring. Changing only one alkyl chain also influenced the performance of dye-sensitized solar cells. Ruthenium sensitizer MJ-10 with bulky substituent harvests visible and near-infrared light, and solar cells sensitized by MJ-10 exhibit an efficiency of 9.1 % under 1 sun irradiation. [ABSTRACT FROM AUTHOR]