Synthesis And Properties Of Planar Binuclear Schiff Base Zinc Phthalocyanines

Dye sensitized solar cells (DSSC) have the characteristics of low cost, high efficiency,environmental friendly. The structure is mainly composed of dye, nano porous membrane,electrolyte and the electrode. Single photosensitive dye adsorpt in the nanoporoussemiconductor electrode act as absorb solar energy and inject the excited electron into nanosemiconductor conduction band.Phthalocyanine is a similarity with biological molecules chlorophyll and hemoglobin.Characteristically photophysical and electrochemical properties attract widespread attention inmany fields, such as photographic printin, liquid crystal, chemical sensor, light-emittingdiodes, photodynamic therapy, solar cells. Phthalocyanine is good at visible light absorption,low cost of synthesis, chemical heat stable performance and structure modify easy. Poorsolubility in organic solvent, difficult to film, easy agglomeration limits the application ofmental phthalocyanine and influences photoelectric conversion efficiency of solar cells.Introducing organic substituents could significantly alter phthalocyanine property. In thispaper, six new planar binuclear Schiff base zinc phthalocyanines were synthesized. Themolecular structures of asymmetric mononuclear phthalocyanine were altered by introducingdifferent substituents, and two asymmetric mononuclear phthalocyanines were connected bySchiff base reaction, in order to improve the photoelectric properties.Asymmetric mononuclear zinc phthalocyanines containing nitro were synthesized by4-nitrophthalonitrile,-naphthol, β-naphthol,8-hydroxyquinoline, isopropanol, tert-butanol,p-Hydroxybenzoic acid and ZnAc in the condition of1,8-diazabicyclo[5.4.0]undec-7-enecatalyst. Then they were reacted with1,4-Phthalaldehyde and formed the new Schiff baseplanar binuclear zinc phthalocyanines.9(10),16(17),23(24)-three carboxyl phenoxy-2(3)-(1,4-methanamide phenyl) binuclear zinc phthalocyanine(bi-CPc),9(10),16(17),23(24)-three -naphthyloxy-2(3)-(1,4-methanamide phenyl) binuclear zinc phthalocyanine (bi--NPc),9(10),16(17),23(24)-three β-naphthyloxy-2(3)-(1,4-methanamide phenyl) binuclear zincphthalocyanine(bi-β-NPc),9(10),16(17),23(24)-three-8-quinolyloxy-2(3)-(1,4-methanamidephenyl) binuclear zinc phthalocyanine(bi-QPc),9(10),16(17),23(24)-threeisopropoxy-2(3)-(1,4-methanamide phenyl) binuclear zinc phthalocyanine(bi-IPc),9(10),16(17),23(24)-three tert-butoxy-2(3)-(1,4-methanamide phenyl) binuclear zincphthalocyanine(bi-TPc).IR, UV-Vis spectroscopy, elemental analysis and1H NMR were used to characterise thestructure of the six complexes. Compared to the six planar binuclear zinc phthalocyanines inN,N-dimethyl formamide (DMF) solution by UV-Vis spectrum; The six complexes theground state oxidation potential and excited-state oxidation potential of the energy levelposition were determined by the UV-Vis spectroscopy, cyclic voltammetry curves anddifferential pulse volammetry. The assemblies of DSSC photovoltaic performance weremeasured respectively.The results showed that compared with unsubstituted phthalocyanine(only in dimethylsulfoxide (DMSO) and DMF partly dissolved), six planar binuclear Schiff base zincphthalocyanines have good solubility in benzene, chloroform and acetone, et al. The UV-Visspectrum of six planar binuclear zinc phthalocyanines in DMF showed the maximumabsorption peak of Q band around670-690nm. Six Schiff base planar binuclear zincphthalocyanines dye sensitizers excited state level range from-0.87V to-0.99V by cyclicvoltammetry curves, and nanometer TiO2conduction band energy level location match; totalphotoelectric conversion efficiency of (η) are:0.774%,0.682%,0.905%,0.734%,0.564%,0.632%.