Molecular Crystals and Liquid Crystals, Vol.618, No.1, 13-20, 2015
Highly Luminescent Red Phosphorescent OLED with Interfacial Layers for Hole Transport and Electron Injection
Four kinds of red phosphorescent organic light-emitting devices were fabricated and compared to investigate the effect of interfacial layers for hole transport and electron injection. 1nm-thick LiF in the device A and C and 1nm-thick Cs2CO3 in the device B and D were deposited as an electron injection layer between the anode and the electron transport layer, and 5nm-thick layer of dipyrazion[2,3-f:2,2-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile[HATCN] was inserted as a hole transport interfacial layer between the hole injection layer and the hole transport layer only in the device C and D. Under a luminance of 1000 cd/m(2), the power efficiencies were 7.6 lm/W and 8.5 lm/W in the device A and B, and 8.6 lm/W and 13.4 lm/W in the device C and D. The quantum efficiency of the device D was 15.8% under 1000 cd/m(2) which was somewhat lower than those of the device A and C, but a little higher than that of the device B. The luminance of the device D was much higher than those of the other devices at a given votage. The luminance of the device D at 7V was 23,710 cd/m(2), which was 13.0, 3.4, and 4.0times higher than those of the device A, B, and C at the same voltage, respectively.