White organic light-emitting diodes based on exciton and electroplex dual emissions

Two new blue-light-emitting materials based on tetraphenylethylene (TPE), TPE-4Br, and TPE-3Br have been designed and synthesized. They have been used as emitting materials in organic light-emitting diodes (OLEDs) and have been found to form electroplex with an appropriate neighboring hole or electron transporting layer. Using the intrinsic local exciton emission and electroplex emission, desirable white electroluminescence has been obtained. Using TPE-4Br and TPE-3Br in 1,3-di(9H-carbazol-9-yl)benzene (mCP) matrix as the 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 the hole and electron transporting layers, respectively, Device A and Device B have been fabricated with the corresponding CIE coordinates of (0.32, 0.33) and (0.31, 0.34) at 9 V. Device B showed the maximum luminance of 364.66 cd∙m⁻² and the maximum current efficiency of 0.79 cd·;A⁻¹.