Synthesis of phthalocyanines with two carboxylic acid groups and their utilization in solar cells based on nano-structured TiO₂

Abstract

A way of anchoring unsymmetrical phthalocyaninato-metal complexes (metal ion: zinc and ruthenium) is described. The synthesis and characterization of these complexes are presented. In case of the zinc complex, the obtained product is an aggregate, while only the monomer is obtained in the case of the ruthenium derivative. Both complexes could be attached onto the TiO 2 surface by using the reported method. Both dyes are expected to form monolayers with dye molecules standing on the surface of nano-structured TiO 2 , forming higher-order aggregates with the zinc but not with the ruthenium complex. A highest monochromatic incident photo-to-current conversion efficiency (IPCE) of 1.6% at 690 nm was obtained for a solar cell based on the Pc-Zn sensitized nano-structured TiO 2 electrode, while an IPCE of 23% at 630 nm was obtained for the Pc-Ru sensitized electrode. Overall conversion efficiencies (η) at a simulated AM 1.5 (100 W.m -2 ) of 0.03% and 0.40% for the zinc and ruthenium complexes were achieved, respectively. The difference in efficiencies could be due to the formation of face-to-face aggregation in the former case. This work shows that the ruthenium complex, with two axial methylpyridine ligands, does not form aggregates in solution nor on the surface of TiO 2 , making it possible for further construction of supramolecular systems with such types of phthalocyanine.

Novel improvements in the sensitizers of dye-sensitized solar cells for enhancement in efficiency-a review

“…The poor efficiency was a result of the poor conduction of electrons due to the improper conjugation of electrons [60]. Many works have been reported on Ru (II) phthalocyanine sensitizers, but these sensitizers were not found to be efficient for DSSCs; the device fabricated with Ru (II) phthalocyanine sensitizers showed efficiency of about 0.04%.…”

“…Many works have been reported on Ru (II) phthalocyanine sensitizers, but these sensitizers were not found to be efficient for DSSCs; the device fabricated with Ru (II) phthalocyanine sensitizers showed efficiency of about 0.04%. The poor efficiency was a result of the poor conduction of electrons due to the improper conjugation of electrons [60]. Many researchers re-designed these dyes with push-pull concept, like introducing three bulky tertbutyl groups or six alkoxy groups in the molecular structure, which assist in electron releasing 'push' and carboxylic groups acting as electron releasing 'pull'.…”

Two main chain polymeric metal complexes as dye sensitizers for dye‐sensitized solar cells based on the coordination of the ligand containing 8‐hydroxyquinoline and phenylethyl or fluorene units with Eu(III)

“…Despite recent advances in DSSCs materials, for example, Zn(II) metal‐porphyrins compounds,30, 31 Ru‐sensitized DSSCs exist in which the dye is attached to the TiO 2 via axial ligands32–34 or through anchoring groups on the macrocycle periphery,35 research into ligand design for electronic materials has been dominated by the dipyridine and azaindole moiety. Furthermore, practical applications of these compounds in DSSCs would require a new generation of organic ligands that are inexpensive and robust.…”

Inter‐ and Intramolecular Interactions in Some Supramolecular Photochemical Systems

“…The molecules are well known as dyes due to their chemical and thermal stability and very strong characteristic optical absorption in the visible region, the so-called Q-band at around 700 nm, which has been assigned to the lowest-energy 1 p-p* transition. [16] A variety of applications of Pc, especially in biological systems [17] and solar-energy conversion, [18] have aroused considerable interest. TTF and its derivatives are well known for their electron-donating properties.…”