Design And Property Investigation Of Large-Steric Organic Fluorescent Functional Materials

Organic functional materials are generally used in form of solid state for practical application.Investigation of the photophysical characteristics of organic materials in condensed-state not only helps to understand the essential mechanism but to guide further modification of organic functional materials for advanced applications.In this work,we firstly developed white organic light-emitting diode using both the local emission and electroplex emission which formed between the lightemitting and carrier-transporting layers.Then,based on pressure-dependent luminescent properties caused by corresponding molecular conformational changes,we have demonstrated luminous ultra-high pressure sensor.Herein we present our research progress as follows:1.Two new blue-emitting materials based on tetraphenylethylene(TPE),1,1,2,2-tetrakis(4-bromophenyl)ethene(TPE-4Br)and 4-(1,2,2-tris(4-bromophenyl)vinyl)-1,1'-biphenyl(TPE-3Br)have been designed and synthesized.Utilizing TPE-4Br and TPE-3Br in 1,3-di(9H-carbazol-9-yl)benzene(mCP)matrix as emitting layer,4,4'-(cyclohexane-1,1-diyl)bis(N,N-di-p-tolylaniline)(TAPC)and 3,3'-(5'-(3-(pyridin-3-yl)phenyl)-[1,1':3',1''-terphenyl]-3,3''-diyl)dipyridine(TmPyPB)as hole-and electron-transporting layer,respectively,desirable white organic light emitting diodes(WOLED)with CIE coordinates of(0.32,0.33)has been demonstrated.2.Dyanovinyl-substituted aromatic compound,2,2'-([9,9'-bianthracene]-10,10'-diylbis(methanylylidene))dimalononitrile(DAAD)and Diphenyl sulfone-substituted aromatic compound,10,10'-bis(phenylsulfonyl)-9,9'-bianthracene(PAAP)have been synthesized,respectively.Their basic photophysical properties have been studied and emission property—when molecularly dispersed in a polymer matrix—are investigated under pressure perturbation.The DAAD system shows that as the applied pressure increased,the fluorescence emission red shifts 140 nm,accompanied by emission intensity firstly increased and then weakened.Computational studies indicates that,as the applied pressure increased,the dihedral angle between the anthracene rings dereased firstly and then the dihedral angle between the anthracene ring and bis(cyano)-subtituted vinyl group decreased.The curve,based on the change of maximum emission wavelength with pressure,shows a good linear relationship fitted as a function of P=0.11?max-63.32 with correlation coefficient 0.9955.For the PAAP system,as the applied pressure increased,the fluorescence emission red shift 150 nm with the emission intensity gradually decreased.These results show that these materials indicate prospective potentials for ultra-high pressure sensing,concerning the advantages of wide-range pressure detection and in-situ naked-eye observation.