Synthesis And Photoelectric Properties Of Bisphenol Dye Modefied Titanium Oxo Clusters

Titanium oxide materials have a wide range of applications in photoelectric conversion,photocatalysis,and photodegradation.Titanium oxo cluster is a kind of molecular compound which is similar to TiO₂ but has a discrete structure.It is an intermediate product obtained by hydrothermal synthesis of TiO₂ nanomaterials.In addition,its definite structure provides a basis for in-depth study of titanium oxide materials.Therefore,considerable attention has been paid to the research on the synthesis method,structure and properties of titanium oxide clusters.Owing to its excellent photoluminescence,photoelectric conversion and photocatalytic properties,the study on the organically modified titanium oxo clusters is of great significance.Although some titanium oxide clusters with organic molecules have been reported,the research on such titanium oxide clusters,especially on the multi-ligand modified titanium oxide clusters,is still limited and remains to be further explored.In this dissertation,a new type of organic-inorganic hybrid titanium oxide clusters with organic diphenol dyes as ligands were synthesized using simple solvothermal synthesis method.Meanwhile,the synthesized titanium oxide clusters were utilized as model compounds for dye-sensitized solar cells,and their structures,charge transfer and photoelectric properties were explored,moreover the synergistic effects of multi-ligand systems were first discussed in our work.This dissertation mainly includes the following contents:?1?In chapter 1,a brief introduction of the recent development of titanium-oxygen clusters was made and the applications of titanium-oxygen clusters in photoelectron conversion,photoluminescence,photocatalysis,and photodegradation were summarized.?2?In chapter 2,a series of alizarin molecules and auxiliary ligands modified titanium oxo clusters,[Ti₂?Oⁱ Pr?₅?Az??X-BA?][Az=alizarin,BA=Substituted benzoic acid,X=NO₂?1?,F?2?and Br?3?]were synthesized by solvothermal method.These compounds were coated on TiO₂ electrodes as a novel photosensitizing dye and their photo-responsive properties in I₂/I₃^-electrolyte were tested.The experimental results showed that after dye modification of titanium oxide clusters,the light absorption of the compounds is shifted to a lower energy band due to the charge transfer from the?-conjugated dye moiety to Ti?IV?,the hydrolysis of the alkoxy moiety improved the anchoring properties of the dye molecules on the TiO₂ surface,and consequently,the photocurrent density was increased.More importantly,the effect of the auxiliary ligand on the photocurrent density was studied for the first time,and the research pointed out that the electron-withdrawing auxiliary ligand is advantageous for improving the photoelectric conversion efficiency.?3?In chapter 3,a series of esculetin dye molecules and 1,10-phenanthroline/2,2-dipyridinemodifiedtitaniumoxoclusters[Ti₁₀O₈?OⁱPr?₁₂?esc?₄?phen?₂]?4?,[Ti₁₀O₈?OⁱPr?₁₂?esc?₄?bpy?₂]?5??esc=4-methy esculetin,phen=1,10-phenanthroline,bpy=2,2-dipyridine?were synthesized by solvothermal method,and characterized by single crystal X-ray diffraction.The results of UV-vis-NIR spectroscopy showed that,the charge which transferred from the dye ligand to the titanium oxygen skeleton enhanced the absorption of visible light;the transmission electron microscopy analysis showed that,the clusters disperse into thin nanostructures in dichloromethane solution.The fluorescence properties of methylene chloride solution were measured,and the effects of the concentration on the fluorescence of the methylene chloride solution were investigated.It was found that increasing the proportion of alcohol increased the fluorescence intensity,and the compound also had better photoelectric response properties.