초록 |
We demonstrated green organic lighte-emittin diodes (OLEDs) improved by co-doped using hole transport material, N′-bis-(1-naphyl)-N,N′-diphenyl-1,1′-biphenyl-4,4′-diamine (NPB) and electron transport material, bis(2-methyl-8-quninolinato)-4-phenylphenolate aluminum (Balq), into emitting layer. The co-doped materials improve charge blance by injecting hole and electron into emitting layer, so more hole and electron are combined and form much exciton which advance device performance. The device of co-doped hole transport material, NPB, exhibits a luminance of 20620 cd/m2 and efficiency of 8.93 cd/A and quantum efficiency of 3.28 % which shows superior properties than others. |