Emission Characteristics of Red OLEDs in the Emitting Layer Position Doped with DCM2 and Rubrene

In this study, we have fabricated the red OLED (organic light emitting diode). The basic device structure is ITO/hole transporting layer, TPD(500 Å)/red emitting layer, Alq3 doped with DCM2:rubrene(20 Å)/electron transporting layer, Alq3(M) (500 Å-M Å)/LiF(15 Å)/Al(1,000 Å). The thickness of electron transporting layer(500 Å-M Å) changed 0, 20, 40, 60 Å. Turn on voltage of the red OLED was 5 V, 6 V, 6.5 V and 7.5 V , respectively with electron transfer layer changed ratio. Luminance of red OLED was 4,504, 1,840, 1,490 and 1,130 cd/m2, respectively. Optimized electron transfer layer position changed ratio of the red OLED was 0 Å.