基于新型电荷生成层的P-i-N结构白色有机叠层电致发光器件

Abstract

Organic light emitting diodes(OLEDs) were fabricated using 5 wt.% cesium carbonate(Cs2CO3) doped 2,9-Dimethyl-4,7-diphenyl-1,10-phenanthroline(BCP) as eletron-injection layer and 20 wt.% molybdenum oxide(MoO3) doped N,N’-Bis(naphthalen-1-yl)-N,N’-bis(phenyl)-benzidine(NPB) as hole-injection layer,respectively,and the carrier transfer characteristics were examined.The lowered driving voltage suggests BCP: Cs2CO3 and NPB: MoO3 efficiently enhance carrier injection in OLEDs.Color-stable and efficient tandem P-i-N white organic light emitting diode(WOLED) with a new charge generation layer,which consists of BCP: 5 wt.% Cs2CO3/NPB: 20 wt.% MoO3,has been fabricated.The maximum current efficiency of the two-unit tandem P-i-N orange device is enhanced by 2.5 factors with respect to the one-unit device.Such a connecting structure permits efficient opposite hole and electron injection into two adjacent emitting units and gives tandem devices superior electrical and optical performances.The tandem P-i-N WOLED with the charge generation layer,in which the individual orange phosphorescent and blue fluorescent were used as emissive units,exhibits excellent color stability and higher efeciency.The Commission Internationale de l’Eclairage(CIE) chromaticity coordinates almost focus exactly on(0.33,0.29) between 500 cd/m2 and 5 000 cd/m2,which closes to the point of equal energy(0.33,0.33).The results may prove the method to be effective to enhance the current efficiency and color-stable of WOLED.