The adsorption of 4-tert-butylpyridine on the nanocrystalline TiO2 and Raman spectra of dye-sensitized solar cells in situ

In this article, we studied the adsorption of 4-tert-butylpyridine (TBP) on the nanocrystalline TiO2 (anatase) powder by Raman, IR and XPS. In Raman spectra, the free TBP and physisorbed TBP showed the totally symmetric ring breathing mode at 996 cm−1 and the vibration of the trigonal symmetry ring stretching mode was too weak to identify, while the coordinated TBP produced the characteristic trigonal symmetry ring stretching mode at 1022 cm−1 and the vibration of the totally symmetric ring breathing mode shifted from 996 to 1007 cm−1. From Raman spectra of dye-sensitized solar cells in situ, the Raman line at 167-169 cm−1 should be assigned to the formation of TBP·I2 or iodine adsorbed on the dye. Since there were significant differences from 100 to 300 cm−1, we suggested that TBP, besides the adsorption on TiO2, can also remove iodine adsorbed on the dye to suppress the rate of interfacial electron transfer from the conduction band of TiO2 to iodine.