The efficiency of dye-sensitized solar cells (DSSCs) using Ru complex dyes and Co complex redox couples has been increased with a strategy to prevent charge recombination via the addition of bulky or lengthy peripheral units to the dyes. However, despite the efforts, most of the DSSCs are still suffering from nonunity quantum efficiency and fast recombination. We examine the effect of SCN ligand, which has been used for many Ru complex dyes and could attract positively charged Co complexes. We find that replacing the ligands with 2,6-bis(2'-(4'-trifluoromethyl)pyrazolyl)pyridine increases the quantum efficiency and electron lifetime. With the combination of the replacement of SCN ligands and the addition of bulky moiety, ∼80% external quantum efficiency is achieved. These suggest that not only the addition of a blocking effect but also the reduction of electrostatic and dispersion forces between dyes and Co complexes are essential to control the charge separation and recombination processes.

Two three-dimensional (3D) network polymers (1 and 2), in which zinc­(II) or cobalt­(II) phthalocyanines were interconnected with twisted 9,9′-spirobifluorene linkers, were synthesized in order to investigate their performance as heterogeneous catalysts for thiol oxidations. From the spectroscopic analyses of two dimers (3 and 4) as component units of the network polymers, 3 connected with a short linker revealed electronic interaction between the two phthalocyanine units. Micrometer-sized polymer particles were formed due to the condensation of the twisted 9,9′-spirobifluorene linkers in the presence of zinc or cobalt ions. The dispersed solutions of 1 and 2 had sharp Q-bands, indicating the prevention of stacking among phthalocyanine moieties within the polymers. Powdered X-ray diffraction pattern and N2 adsorption–desorption analyses suggested that 1 created small and rigid cavities as compared with 2 through the regular spatially arrangement of the phthalocyanine moieties in the 3D networks. The photocatalytic and catalytic activities of 1 and 2 for thiol oxidations using molecular oxygen were examined. We found that the catalytic activity of 1 was higher than that of 2 having larger cavities.

A combination of Ru complex sensitizers and Co complex redox couples for dye‐sensitized solar cells (DSSCs) generally results in low power conversion efficiency. This has been suggested to be from undesired electron transfer due to strong intermolecular interactions between the dye and the redox couple. To retard the interactions, two thiocyanate‐free ruthenium (Ru) sensitizers were synthesized with a terpyridine attached that has a triphenylamine (TPA) unit with branched alkoxy chains. The main difference between the two dyes is the angle of the three phenyl rings in the TPA unit. The DSSCs using both the new dyes show higher short‐circuit currents and open‐circuit voltages in comparison with those using a Ru complex dye with nonbranched alkyl chains. The Ru sensitizer with a more twisted TPA unit displays relatively high power conversion efficiency without coadsorption of chenodeoxycholic acid, suggesting less intermolecular interaction among dyes and thus also with Co complex redox couples.