Improvement of OLEDs' performance with graphene doped in NPB as hole transport layer

The organic light emitting diodes (OLEDs) using graphene doped in N,N '-bis-(1-naphthyl)-N,N'-diphenyl-1,10-biphenyl-4,4'-diamine (NPB) (NPB:Graphene) as hole transport layer was fabricated in this study. The structure of device was ITO/NPB:Graphene (20 wt%) (50 nm)/aluminum tris (8-hydroxyquinoline) Alq(3) (80 nm)/LiF (0.5 nm)/Al (120 nm). The results of this device was compared with the standard device to study the effect of NPB: Graphene on the OLEDs' performance, showing that the device used graphene doped in NPB as hole transport layer presents better performance under the same conditions. When the current density was 90 mA/cm 2, the maximum current efficiency would achieve 3.40 cd/A, increased by 1.49 times compared with the standard device, and the maximum luminance of this device would achieve 10,070 cd/m(2) at 15 V, increased by 5.16 times than the maximum luminance of standard device.