A novel emission material bis(2-biphenyl-4'-yl-8-quinolinolato)zinc {Zn[2-(p-biPh)-8-Q-O]₂} was synthesized and confirmed by ¹H NMR and UV-Vis measurements. White organic light-emitting diode with a structure of ITO/NPB (N,N'-di(1-naphthyl)-N,N'-diphenyl-(1,1'-biphenyl-4,4'-ylenediamine)/BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline)/Zn[2-(p-biPh)-8-Q-O]₂/Al was fabricated and its electro- luminescent mechanism was studied. The mixture light from double emitting materials of NPB (blue-light emission) and Zn[2-(p-biPh)-8-Q-O]₂ (yellow-light emission) was achieved by effectively adjusting the thickness of BCP that functioned as a hole blocking layer. When a 2.0 nm-thick BCP was used, white-light emission was obtained. With a lower turn-on voltage at about 6 V, the white OLED showed a maximum brightness of 130 cd/m² and current efficiency of 0.224 cd/A at 20 V.

Key words: white organic light-emitting diode, hole blocking layer, bis(2-biphenyl-4'-yl-8-quinolinolato)- zinc, 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline