Synthesis And Properties Of Substituted Ethylene-based Fluorescent Materials With AIE Property

In 2001,Tang Benzhong's group found that the compound HPS is non-emissive in tetrahydrofuran dilute solution,but the luminescence intensity of its nano-aggregates formed in high-viscosity or low-temperature solution will be enhanced remarkably.This phenomenon was called aggregation induced emission?AIE?.The raise of AIE effect has completely subverted the traditional recognition of scientific researchers on aggregation-caused quenching?ACQ?.The material with AIE effect can overcome the problem of fluorescence quenching brought by ACQ effect,which has wide application in the fields of optoelectronic devices,sensor,etc.In this paper,a substitued ethylene-based derivative DCBPm molecule with ethylene as the core and carbazole,pyrimidine and trifluoromethyl as building blocks was synthesized.Its structure was characterized by ¹H-NMR,¹³C-NMR and X-ray single crystal diffraction.This compound was found to exhibit aggregation-induced emission property due to highly twisted conformation and have tow crystalline polymorphs,whose exhibited green?g-crystal?and blue?b-crystal?fluorescence,respectively.The different emissions of the polymorphs were found to be mainly depended on their molecular conformations due to the weak intermolecular interactions,as revealed by the single crystal structural analysis.Its decomposition temperature?T_d?is 419?,glass transition temperature?T_g?is 123?and melting point?T_m?is 248?,which has excellent thermal stability can ensure its application in optoelectronic devices.Eventually,organic light emitting diodes?OLEDs?doped devices with the following confguration were fabricated:ITO/PEDOT:PSS?30nm?/PVK?10nm?/CBP:DCBPm?30nm?/TmPyPB?65nm?/LiF?1nm?/Al?100 nm?,the turn-on voltage is 4.2 V,maximum luminance(L_max),current efficiency(CE _max)and power efficiency(PE_max)are up to 3515 cd m^-2,5.4 cd A^-1 and 3.3 lm W^-1,respectively.