Synthesis, Characterization And Properties Of Porphyrins Schiff Base Photosensitizers

Porphyrins are a kind of highly conjugated system of24center26electron,which havegood thermal stability, chemical stability, and the significant efficiency and rate of electroninjection. In addition, porphyrins have strong modification, can introduce different substituents,which have been widely applied in every fields; Due to C=N bond, theschiff base compoundsshow the good electro-optical properties, and the synthesis of that is simple, so they have beenused as functional materials. In this paper, five new schif-f base porphyrin-sensitized dyes havebeen synthesised successfully and applied in dye-sensitized solar cells, including three kindsof symmetric schiff base porphyrins, two kinds of schiff base porphyrin dimers, Though theintroduction of different substituents and C=N bonds, the molecular structure are changed toexpanded spectral range, make electron directivity in dye molecules, and to improve thephotoelectric properties.Five new schif-f base porphyrin-sensitized dyes were synthesized by imidazole,4-fluorobenzaldehyde, redistilled pyrrole, benzaldehyde,4-nitrobenzaldehyde,2-Thiophene-carboxaldehyde, p-methyl benzaldehyde, paraformaldehyde, zinc chloride, hexamethyl enetet-ramine, zinc acetate, which were meso-tetra [p-(p-benzal imido)] phenyl zinc porphyrin (Ⅱ)(TBIPP-Zn), meso-tetra [p-(2-thenylidene imido)] phenyl zinc porphyrin(Ⅱ)(TTIPP-Zn),meso-tetra[p-(p-N-imidazolyl benzal imido)] phenyl zinc porphyrin(Ⅱ)(TIIPP-Zn),p-(10,15,20-triphenyl-5-porphyrinyl) benzylidene aminophenyl-10,15,20-(p-methylphenyl)porphyrin (TPBAMP), p-(10,15,20-triphenyl-5-porphyrinyl) benzylidene aminophenyl-10,15,20-(2-thienyl)porphyrin (TPBATP).The structure of the five kinds of porphyrin compounds were characterized by UV-visiblespectroscopy, infrared spectroscopy (IR), elemental analysis, and H NMR spectroscopy. Compared UV-visible spectrums in N,N-dimethyl formamide (DMF) solution and itssensitized TiO2thin films, and calculated the ground state oxidation potential(HOMO) andexcited-state oxidation potential (LUMO) of the energy level position of the five porphyrindyes, combining with the UV-visible spectroscopy, cyclic voltammetry curves and thedifferential pulse voltammetry, then measured photovoltaic performance of dye-sensitizedsolar cells (DSSC) by the assembly.In result, The Uv-vis spectrums of five porphyrin compounds sensitized TiO2thin filmsred shifted and broadened compared with that of in DMF solution, which were all at300nm-700nm, the wavelength of maximum absorption of which were at about400nm, allred shifted in comparison with tetraphenyl porphyrin, porphyrin dimers red shifted moreobviously than single-porphyrin molecules. The excited-state energy level range of the fiveporphyrin dyes from-0.90V to-1.08V, which matched with Nano-TiO2conduction band.Photoelectric conversion efficiency (η) were respectively0.65%，0.75%，0.86%，2.44%，2.86%, and gave a better performance.