Thermally Cross-Linkable Hole-Transporting Materials for Improving Hole Injection in Multilayer Blue-Emitting Phosphorescent Polymer Light-Emitting Diodes

TLDR: In this article, a series of thermally crosslinkable 4,4′,4,4.4′-tris(N-carbazolyl)triphenylamine (TCTA) derivatives have been synthesized to explore their function as efficient hole-transporting materials for blue-emitting electrophorphorescent devices.

Abstract: One of the most challenging tasks in fabricating multilayer polymer light-emitting diodes (PLEDs) is to develop robust hole-transporting materials that possess matched energy level with indium tin oxide (ITO) anode and the highest occupied molecular orbital (HOMO) of light-emitting polymers to facilitate efficient hole injection and transport. In this article, a series of thermally cross-linkable 4,4′,4′′-tris(N-carbazolyl)triphenylamine (TCTA) derivatives have been synthesized to explore their function as efficient hole-transporting materials for blue-emitting electrophorphorescent devices. In particular, their excellent solvent resistance enables them to be used in the double hole-transporting layer (HTL) device configuration to facilitate cascade hole injection. The effects of cross-linking temperature and the functional group on the compatibility between two HTLs are investigated through optical and atomic force microscopy. When vinylbenzyl ether is used as the cross-linking group for TCTA, it shows t...