Synthesis And Properties Of Triphenylamine-based Hole Transporting Materials Containing Ethenyl Unit

The hole transport material is one of the most important organicelectroluminescent materials, which could improve the injection efficiency and thetransmission efficiency of the holes in the device effectively. Since the small moleculehole transport material have a good performance, but there are certain disadvantages,seeking novel small molecule hole transporting materials which can be soluble incommon solvents and have good film-forming properties, high thermal stability andsuitable HOMO level has become a very important topic.At first, the synthetical conditions of4-(2,2-diphenylethenyl)-N,N-bis[(4-methyl) phenyl] aniline were studied in the paper. The relationship between yieldand reaction conditions, such as reaction time, temperature and the molar ratios of rawmaterial of the wittig-horner reaction were investigated and the optimal reactionconditions have been determined：using DMF as the solvent, t-BuOK as the base catalyst,the molar ratio of triethylphosphite/bromodiphenylmethane/4-bis4’-methylphenyl-aminebenzald ethyde/t-BuOK is5:1:0.7:1.2, react at15℃for4h and the yield is97.94%.The10times amplification synthesis were conducted under the above conditions andgot the average yield of96.79%. The compound was characterized by1H NMR,13CNMR, FT-IR and MS. The organic photoconductive devices based on the titledcompound as hole-transporting materials showed excellent xerographic performance,V0=550V，VR=10V，Rd=10V/s, E1/2=0.6lux·s.The compounds containing butadiene moiety use as Hole Transporting Materials(HTM) are characterized by high hole mobility and forming film without the additionof polymers. So in this paper, three new triphenylamine-based hole transportingmaterials (HTM1-HTM3) containing butadiene moiety was synthesized viawittig-horner reaction. All of the compounds were characterized by infrared spectrum(IR), proton nuclear magnetic resonance (1H NMR) and mass spectrum (MS)technology. The quantum chemistry calculation results illustrated that the geometry ofthe compounds is benefit to inhibit the crystallization of the compounds effectively.Energy band structure, thermal stable properties and fluorescence property also havebeen investigated. The data shows that the compounds exhibit two absorption bonds at the region of275nm~301nm and380nm~406nm, respectively. The HOMOlevels of HTM1-HTM3are-5.22eV,-5.12eV and-5.04eV, respectively; The TgofHTM1-THM3are58℃,68℃and78℃, respectively; The maxima emissionpeaks are located at487nm,481nm and517nm, respectively, corresponding to blueto yellow-green light emission. These materials have the fluorescence quantum yieldare85.7%,2.4%and43.0%and their fluorescence life are1.80ns,0.79ns and3.68ns, respectively. The crystallinity of the films studied by X-ray diffraction (XRD)which suggesting that they could formamorphous filmby spin-coasting.