Characteristics of white OLED using Zn(phen) as a yellowish green emitting layer and BCP as a hole blocking layer

We synthesized the emissive material [(1,10-phenanthroline)(8-hydroxyqui-noline)] also known as Zn(phen)q. We studied white OLED using Zn(phen)q as a yellowish green emitting layer, N,N′-bis(1-naphthyl)-N,N′-diphenyl-1,1′-biphenyl-4,4-diamine (NPB) as a hole transporting layer and blue emitting layer, and varying thicknesses of 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) as a hole blocking layer. The fundamental structures of the OLED were ITO/NPB (40 nm)/BCP/Zn(phen)q (50 nm)/LiF/Al. We varied the thickness of the BCP layer from 0 to 5 to 10 nm. When the thickness of the BCP layer was 5 nm, white emission was achieved. We obtained a maximum luminance of 5400 cd/m2 at a current density of 650 mA/cm2. The CIE coordinates are (0.26, 0.33) at a voltage of 10 V.