Organic light-emitting devices using polyacene derivatives as a hole-transporting layer

Three polyacene derivatives, 2-tert-butyl-9,10-di(2-naphthyl)anthracene (TBADN), 9,9('),10,10(')- tetraphenyl-2,2(')-bianthracene, and 5,6,11,12-tetraphenylnaphthacene (rubrene), are found to successfully function as hole-transporting layers (HTLs) in red organic light-emitting devices (OLEDs) using tetraphenyldibenzoperiflanthene as an emitter. Compared with an OLED with the most widely used HTL material, the arylamine derivative, 4,4(')-bis(N-phenyl-1-naphthylamino)biphenyl (NPB), the OLEDs with the polyacene derivatives exhibit advantageous performance such as lower driving voltage, higher electroluminescence efficiency, or longer luminance lifetime, depending on the employed HTL material. Current efficiency of the red OLED with a TBADN HTL is 5.5 cd/A with Commission Internationale de L'Eclairage chromaticity coordinates of (x=0.66, y=0.34), which is much higher than the value of 2.1 cd/A with the same chromaticity for the OLED with a NPB HTL. The driving voltage and luminance lifetime of the red OLED with rubrene HTL are improved compared with the OLED with a NPB HTL. The hole injection properties of the proposed HTL materials are discussed. The results indicate that the polyacene derivatives are promising for use in OLEDs as a class of HTLs, expanding the variety of HTL materials available for optimizing the performance of OLEDs. (c) 2006 American Institute of Physics.