The Theoretical Investigation For Optoelectronic Properties Of Triphenylamine Derivatives Constructed With Electron-deficient Heterocycles

The development of low cost and high efficiency theoretical calculation method can guide and optimize the synthesis of triphenylamine organic photoelectric dyes,greatly reducing the time and resources consumed by the experiment.Our group has synthesized a series of triphenylamine-triazine dyes,and carried out structural characterization and electrochemical tests previously.In this paper,the theoretical calculation method has been used to simulate the geometrical structure,electronic structure of these compounds.And the photochemical tests of the compounds were carried out to investigate the effect of the modification of the electron donor on the structure and photophysical processes of the triphenylamine-triazine photo induced electron transfer systems.The results show that the lifetime of the charge separation state increases with the increase of the electron capacity of the donor part,and the back electron transfer driving force and electron transfer recombination energy work together to determine the life of the charge separation state formed by this series of compounds.In this paper,the geometrical structure,electronic structure and absorption spectra of a series of triphenylamine-pyrimidine dyes monomer and dye-?TiO₂?₉adsorption systems were studied by density functional theory.The results show that the reason for the formation of the charge separation state of the triphenylamine-pyrimidine dyes is that the introduction of the pyrimidine ring weakens the interaction between the donor and the acceptor so that the HOMO-LUMO orbital of the dye molecule is almost segregated,inhibiting the HOMO-LUMO orbital transition.In the transition from the ground state of the dyes to the first excited state,the electron of the HOMO orbit is transferred to the LUMO+1orbit,and the electron is further transferred to the LUMO orbit to form the charge separation state.The modification of the donor moiety,the addition of the strong electron-withdrawing group,the introduction of the heterocyclic ring and the insertion of the aminoethylamino group were used to modify the triphenylamine-pyrimidine dye for the purpose of designing new charge separation dyes.The results show that the introduction of simple structure electron-donating group in the triphenylamine is an effective modification method.The introduction of one or two cyano groups at the ortho position of the vinyl group and the introduction of a cyano group in the ortho and meta position of the vinyl respectively not only expand the absorption spectra of the dyes but also change the contribution of the orbital transition.The introduction of heterocyclic ring achieve the two-way regulation of the orbital energy level,expanding the absorption spectra.The insertion of the aminoethylamino groups causes the donor moiety to be relatively independent of the acceptor moiety.The transition of the ground state of the dyes to the first excited state is dominated by the HOMO-LUMO+1 orbital transition,and the modification of the donor part can form new type efficient charge separation dyes.