Study On Synthesis And Properties Of Photosensitizers For Dye-Sensitized Solar Cell

Solar cells have been being an important aspect of development and utilization of solar energy. The key to improve dye-sensitized photoelectric conversion efficiency of solar cells was to develop new photosensitizers with high photoelectric conversion efficiency and high stability. For this purpose, dye intermediate and Cy7 condensing agent were synthesized, then symmetrical Cy3, asymmetrical Cy3 and symmetrical Cy7 photosensitizers were designed and synthesized form them, and properties of the dyes were studied.Dye intermediate was synthesized from sulfonic acid, methylisopropyl ketone and p-chloromethyl benzene carbonic acid by diazotization, reduction, and other reactions.The methods of oil bath and water bath under ultrasonic for the syntheses of symmetrical Cy3, asymmetrical Cy3 and symmetrical Cy7 by the condensations of the intermediate with triethyl thoformate and 5 - phenylamino-pentadiene aldolase dihydrochloride were studied. The products were confirmed by 1HNMR, MS and so on. Comparing with the oil bath method, ultrasonic method made the reaction time shorter, temperature lower and yield higher.Those dyes were separated and purified by SiO2 column chromatography. The best eluants of symmetrical Cy3, asymmetrical Cy3 and symmetrical Cy7 were investigated respectively. The best ratios were isopropyl alcohol :water =5:1 for symmetrical Cy3, acetic acid glacial: n-butyl: water = 7:80:5 for asymmetrical Cy3 and acetic acid glacial: n-butanol: water = 5:32:5 for symmetrical Cy7.The spectral properties of products were tested. The maximum UV absorption wavelengths of them were 551 nm, 544 nm and 749 nm and the maximum fluorescence emission wavelengths were 565 nm, 561 nm and 787 nm in water respectively. Compared with those of the dyes in water, the maximum UV absorption wavelengths and fluorescence emission wavelengths of them were little change but the strengths were change inа-CD.The impedances of photoelectrodes prepared from nano-TiO2 electric glass sensitized by the dyes were tested by the electrochemical workstation. Symmetrial Cy3, asymmetrical Cy3 and symmetrical Cy7 could widen and strengthen the photo absorption of TiO2. Because of having good photosensitivity and stability, symmetrial Cy3, asymmetrical Cy3 made photo absorption of the photoelectrode increased, the charge transfers of electrolyte / oxide interface fast, and the impedances decreased. But the impedance of symmetrial Cy7 was increased because of the weak anti-oxidation capacity of symmetrial Cy7 affecting the photo absorption efficiency of the photoelectrode the resistance of electrons transfer.