Synthesis And Properties Study Of Fluorescent Materials With Aggregation-induced Emission

Although luminescent materials have been developed,many luminescent materials have high luminous efficiency only in solution.Therefore,by adjusting the geometrical structure of molecules and controlling their stacking modes,different molecules can enhance fluorescence and further study compounds with aggregation-induced luminescence（AIE）characteristics,which largely compensate for the lack of luminescence or weak luminescence of traditional optical functional materials in aggregation state.The aggregation-induced luminescent materials have received attention from all walks of life and are widely used in various emerging fields.Among them,Tetraphenylethylene（TPE）/Triphenylethylene（Tr PE）-based illuminants are typical AIE materials,which have excellent luminescent properties,and their functional groups are easy to modify.They are increasingly used in synthesis,and have good application prospects in fields such as electroluminescence,fluorescence sensing and bio-imaging.Among them,TPE and Tr PE derivatives have high solid-state luminescence efficiency,so researchers have made OLED devices with excellent luminescence performance,high efficiency and long life,and many important research results have been achieved in this field.Based on the research work of the predecessors and our research group,on the one hand,two carbazole groups were introduced into the TPE framework,and a novel organic compound with TPE-carbazole conjugated structure,1,2-bis（3,5-di（9H-carbazol-9-ly）phenyl）-1,2-di-p-tolylethene（BDCPDT）was synthesized by Mc Murry-coupling reaction.In addition,we synthesized a new compound（E）-3-（3,5-bis（9H-carbazol-9-yl）phenyl）-2-phenyl-3-（p-tolyl）acrylonitrile（DCPPTA）with good luminescence properties by introducing a carbazole donor and a nitrile acceptor.The structures of the intermediates and target compounds were identified by nuclear magnetic resonance.Both BDCPDT and DCPPTA have a large rigid planar structure,a high HOMO level,excellent hole transport capability,and high charge carrier mobility,high luminous efficiency in solid state.Through theoretical calculation of the target products,the stereostructure and electron cloud distribution can be obtained,and the HOMO and LUMO energy levels can be obtained.Further,the photophysical,electrochemical and electroluminescence properties of the target product are systematically studied.The target products are an aggregation-inducing luminescent materials which are deep blue and sky blue illuminators,respectively.The blue OLEDs prepared from the target products as the light-emitting layers also exhibit good characteristics.The CIE coordinate of the non-doped Device A fabricated by BDCPDT is（0.16,0.10）.It emits deep blue light with a turn-on voltage of 4.79 V,a maximum luminance of 860 cd m^-2 and a maximum current efficiency of 0.81 cd A^-1.Using DCPPTA and DCPPTA doped into CPB as light-emitting layers,non-doped OLED（Device B）and doped OLEDs（Ddevice C,Ddevice D and Device E）were fabricated.Among them,the CIE coordinate of the non-doped device B is（0.22,0.30）,showing sky blue light.Its turn-on voltage,maximum brightness and maximum current efficiency are 4.0 V,506 cd m^-2 and 1.83 cd A^-1,respectively.The CIE coordinates of different doped devices C,D and E are（0.19,0.19）,（0.21,0.24）,（0.23,0.27）.They emit sky-blue light.Their turn-on voltages are 3.9,3.8 and 3.8 V.The maximum brightness of the devices is 2850,3800 and 2940 cd m^-2.The maximum current efficiency is 2.91,3.02 and 3.42 cd A^-1,respectively.