We studied white organic light-emitting diodes using blue fluorescent and red phosphorescent materials.White single OLEDs were fabricated using SH-1 : BD-2 (3 vol.%) and CBP : Ir(mphmq)2(acac) (2 vol.%) as emitting layer (EML). The white single OLED using SH-1 : BD-2 (3 vol.% 8 nm) / CBP : Ir(mphmq)2(acac) (2vol.% 22 nm) as emitting layer showed maximum current efficiency of 8.8 cd/A, Commission Internationale del``Eclairage (CIE) coordinates of (0.403, 0.351) at 1,000 cd/㎡, and variation of CIE coordinates with (0.402 ±0.012, 0.35 ± 0.002) from 500 to 3,000 cd/㎡. The white tandem OLED using SH-1 : BD-2 (3 vol.% 12 nm) /CBP : Ir(mphmq)2(acac) (2 vol.% 18 nm) showed maximum efficiency of 19.6 cd/A, CIE coordinates of (0.354,0.365) at 1,000 cd/㎡, and variation of CIE coordinates with (0.356 ± 0.016, 0.364 ± 0.002) from 500 to 3,000 cd/㎡. Maximum current efficiency of the white tandem OLED was more twice as high as the single OLED. Our findings suggest that tandem OLED was possible to produce improved efficiency and excellent color stability.
