Design,Synthesis And Photo-electrochemical Characteristics Of A Series Of Triphenylamine-carbazole Organic Moieties

The synthesis and photochemical properties of new photosensitive molecules have been a hot topic in recent years.Triphenylamine and carbazole derivatives are commonly used as the building blocks of dyes.The study on the structure and energy level regulation of dyes is of decisive significance for improving the photoelectric conversion efficiency of photosensitive materials.In particular,selecting proper chromophores and matching their energy levels in building nonplanar multichromophoric dyes has been quite a challenging task.The major target of this thesis is to synthetize and tailor the structure of chromophores constructed by triphenylamine-carbazole derivatives.To this end,we have firstly optimized the synthetic conditions and changed the linker between the TPA and Cb groups.This leads to different dihedral angles between the two units,which results in varied spectroscopic properties and energy levels.The steric effect has been thereafter investigated by introducing long alkyl chain into the TPA-Cb derivatives.On one hand,the hexane chain may assist the solubility of parental molecule in organic solvents thus alleviating the reaction conditions and increasing the conversion yield.On the other hand,the bulkyl alkyl chain can enhance the photon to electron conversion efficiency in photoassisted catalysis,dye sensitized solar cells and some other photoelectrochemical devices.In the end of this thesis,the TPA-Cb molecules have been used as sensitizers attaching at TiO₂ surface and have been measured their performance in photocatalytic degradation of acid black pollutants.Reaction types such as Vilsmeier reaction,Wittig reaction and Suzuki reaction have been tried and optimized.Fifteen intermediates and eight target molecules divided into two series have been successfully synthesized.In particular,a few reaction conditions of Vilsmeier reaction have been optimized,which results higher yields as comparied to that reported ones.In the meantime,molecules with and without long alkyl chains have been compared,and the results showed that introducing steric groups during the synthesis can improve the yield under the same reaction conditions.The photophysical and electrochemical properties of the compounds have been investigated using UV-Visible absorption spectroscopy,steady state fluorescence spectroscopy,quantum yield measurements and electrochemistry techniques.To precisely tune the energy level of the molecules,we have focused on tailoring the structures by using similar linker groups.A further photodegradation study of the investigated molecules in acid black pollutant has been proved that all the sensitizers showed excellent decolorization effect on acid black in a short time,especially the two TPA-Cb derivatives TTEC with thiophenyl linker and TOXC with long alkyl chain and ethenyl linker.