Synthesis And Properties Of D-π-A-π-D And D-π-A-π-A Photoelectrical Materials Based On Stilbene Derivatives

Compared to inorganic photoelectrical materials, organic photoelectrical materials have the advantage of being designed and modified easily, and the investigation of new organic photoelectrical materials has attracted a lot of attention due to their potential application in organic electroluminescent devices (OLED), nonlinear optical materials, and optical data storage. The design, synthesis and characterization of organic photoelectrical molecules have become an active and interesting subject.In this thesis, the triarylamine, carbazole, cyano-substituted, and phenothiazine were selected and synthesized as novel organic photoelectrical molecules with multifunction, a series of D (donor)-rc-A (acceptor)-Ï€-D stilbene structrure-like photoelectrical materials were synthesized mainly with Wittig-Horner reaction. Their structures were confirmed by MS, IR and ¹H NMR. The UV-vis spectra, Fluorescence spectra and Fluorescent quantum yields in different solvents w ere measured. The electrochemistry properties had b een d etermined on Cyclic Voltammetry;the influence of structure on the properties of photo-electricity was systematically discussed.The mechanism involved in bromination with NBS was studied, and reaction conditions were also optimized.D-Ï€-A-Ï€-D compounds' (except for phenothiazine-substituted) /λ_F^max was located at 521-575 nm in CH₂Cl₂, D-Ï€-A-Ï€-A compounds'λ_F^maxwas red-shifted, which located at586-618 nm Stoke's shift of these compounds in solvents was longer than 59 nm, and it was also red-shifted when the polarity of solvents increased, the Stoke's shift was over 100 nm in DMF.Their band gaps (E_g) and ionization potentials (P₁) were 2.20-2.61 eV and 5.64-5.90 eV respectively, the electron affinity (E_A) increased remarkably b ecause of the introduction of electron- withdrawing group (-CN), which indicated that compounds were good candidates as electroluminescence emitting materials with good hole-transporting.Compared to D-Ï€-A-Ï€-D compounds, the intermolecular charge transfer (ICT) of D-Ï€-A-Ï€-A compounds increased with the enhancement of the electron affinity (E_A), which might result in high two-photon absorption cross-section.