Cyclic arylamines functioning as advanced hole-transporting and emitting materials

We have developed two kinds of cyclic arylamines functioning as hole-transporting and light-emitting materials of organic light emitting diodes (OLEDs), respectively. The hole-transporting cyclic arylamine (C1)-based device exhibited an improved maximum luminance efficiency of 4.21 cd/A, utilizing a single light-emitting layer of tris(8-hydroxyquinolinato) aluminum. While the maximum luminance efficiencies for N,N′-bis-(naphthyl)-N,N′-diphenyl-1,1′-biphenyl-4,4′-diamine (NPB) and 4,4′,4″-tris-N-naphthyl-N-phenylamino-triphenylamine/NPB-based devices were 2.28 and 3.02 cd/A, respectively. In addition, a non-doped deep-blue (448 nm) light-emitting device was obtained, employing cyclic arylamine (C2) as emission layer. And the exciplex formation occurred at C1/C2 interface or in the emission layer of C2 doped C1, which leaded to a wide EL emission. Furthermore, we have developed a very simple bluish-white OLED using C2 (5 wt.%) doped C1, which showed particularly wide full width at half maximum of 135 nm.