White organic light-emitting diodes based on blue fluorescent bis(2-(2-hydroxyphenyl)benzoxazolate)zinc [Zn(hpb)2] doped with DCM dye
ABSTRACT Bright white organic light-emitting diodes (WOLEDs) with single active layer has been demonstrated from blue emitting zinc complex bis(2-(2-hydroxyphenyl)benzoxazolate)zinc [Zn(hpb)2] doped with orange luminescent 4-(dicyanomethylene)-2-methyl-6-(p-dimethyl-aminostyryl)-4H-pyran (DCM) dye. White light electroluminescence (EL) spectrum from Zn(hpb)2 has been achieved by adjusting the concentration of DCM dye. WOLED with a structure of ITO/α-NPD/Zn(hpb)2:DCM (x%)/BCP/Alq3/LiF/Al has been fabricated. The EL spectra covering the whole visible spectra range of 400–700 nm, with two peaks at 446 and 555 nm has been measured. The device emits white light at 10 V with Commission Internationale de I’ Eclairage (CIE) coordinates (0.27, 0.31) and brightness 1083 Cd/m2. The maximum current efficiency of the device was 1.23 Cd/A at 9.5 V and maximum luminance reaches 2210 Cd/m2 at 12 V.