The Theoretical Research Of The Photophysical Properties For The Nonlinear Optical Material

With the advent of laser technology, photoelectric materials are become the mainpart of information material development. The last century80’s, people paid more andmore attention to the research of organic nonlinear optical materials and devices.Recently, organic nonlinear optical materials were rapid development in the field ofoptical storage, picture processing and ultra-fast optical switch. The researches showthat organic non-linear optical material has the properties of high non-linearpolarizability, high optical damage thresholds, short response, machinability, and lowcost. And we can design and synthesize organic non-linear optical materials withdiffering properties.Photoinduced electron transfer (PET) is a fundamental process that has beenshown to play a key role in determining the efficiency of the photoelectric materials.PET has been widely used in organic photovoltaic cells, fluorescence sensors andcomponents for high-sensitivity optical analytical techniques. Recently, research hasfocused on the mechanism of PET in organic photo-conversion systems with highlyefficient charge-transfer and slow charge recombination, respectively.We now report our investigations into the ground and excited state properties oforganic non-linear optical material using density functional theory (DFT) of quantumchemistry theory and a range of extensive multidimensional visualization techniques.First, the DFT/TD-DFT/UB3LYP(B3LYP)/6-31G**has been used to explore thesinglet biradical character, the second hyperpolarizabilitys, and the charge transferability of the tert-butyl replace Kekule hydrocarbons with the linkers of benzene,naphthaline and anthracene, respectively. The results reveal that the length of thelinker strongly influences singlet biradical character of the system. Then the chargetransfer ability and the second hyperpolarizabilitys of the system are controlled byadjusting the singlet biradical character. Second, the ground state and excited stateproperties of the non-tert-butyl replace Kekule hydrocarbons with the linkers ofbenzene, naphthaline and anthracene, respectively have been researched at theDFT/TD-DFT/CAM-B3LYP (UCAM-B3LYP or M06-2X)/6-31G**(6-31G) level. Our results can be used for rational design and synthesis of organic non-linear opticalmaterials with differing properties by adjusting the linker length and the number ofmolecules (up to three molecules) present in the1D stack of these systems. Finally,we used the DFT/TD-DFT/B3-LYP/def-TZVP to research the excited state propertiesof dimethylaminobenzophenone (DMABP) and DMABP-MeOH dimer. Then, byusing twisting dynamics analysis theoretically, we could obtain the direct evidence forthe configuration relaxation process of the excited state, which accompany twistingmotion. And in alcoholic solvents, due to strong hydrogen-bonding interaction,nonradiative transition of the twisted intramolecular charge transfer state dominatesthe deactivation process via the intermolecular hydrogen bond stretching vibrations.