Effect of different processing methods for the hole transporting layer on the performance of double layer organic light-emitting devices

Abstract

The hole transporting layer (HTL) of organic light-emitting device (OLED) was processed by vacuum deposition and spin coating method, respectively, where N,N′-biphenyl-N,N′-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine (TPD) and poly (vinylcarbazole) (PVK) acted as the hole-transport materials. Tris-(8-hydroxyquinoline)-aluminum (Alq₃) was utilized as both the light-emitting layer and the electron transporting layer. The basic structure of the device cell was: indium-tin-oxide (ITO)/PVK : TPD/Alq₃/Mg:Ag. The electroluminescent (EL) characteristics of devices were characterized. The results showed that the peak of EL spectra was located at 530 nm, which conformed to the characterizing spectrum of Alq₃. Compared with using vacuum deposition method, the green emission with a maximum luminance up to 26135 cd/m² could be achieved at a drive voltage of 15 V by selecting proper solvent using spin-coating technique, and its maximum luminance efficiency was 2.56 lm/W at a drive voltage of 5.5 V.

References

[1] TangC. W., VanslykeS. A.. Appl. Phys. Lett., 1987, 51: 913

[2] KimS. K., ChungT. G., ChungD. H., LeeH. S., SongM. J., ParkJ. W., LeeJ. U., KimT. W.. Optical Materials, 2002, 21: 159

[3] TangC. W., VanslykeS. A., ChenC. H.. J. Appl. Phys., 1989, 65: 3610

[4] KidoJ., IizumiY.. Appl. Phys. Lett., 1998, 73: 2721

[5] ShenZ., BurrowsP. B., BulovicV., ForrestS. R., ThompsonM. E.. Science., 1997, 276: 2009

[6] SheatsJ. R., AntoniadisH., HueschenM., LeonardW., MillerJ., MoonR., RoitmanD., StockingA.. Science., 1996, 273: 884

[7] MullerC. D., FalcouA.. Nature, 2003, 421: 829

[8] BoQ., ZhijianC., FengX., HuayuC., MaomaoH., QihuangG.. Materials Letters, 2006, 60: 1927

[9] FriendR. H.. Nature, 1999, 397: 121

[10] StolkaM., JanusJ. F., PaiD. M.. J Phys Chem, 1984, 88: 4707

[11] ChenC. H., ShiJ., TangC. W.. Macromol Symp, 1997, 125: 1

[12] KimJ. S., CacialliF., ColaA., GigliG., CingolaniR.. Synthetic Metals, 2000, 111–112: 363

[13] NguyenT. Pr., Le. RenduP.. Synthetic Metals, 2003, 138: 229

[14] Ravi KishoreV. V. N., AzizA., NarasimhanK. L., PeriasamyN., MeenakshiP. S., WategaonkarS.. Synthetic Metals, 2002, 126: 199