A new thermally crosslinkable hole injection material for OLEDs

A new thermal cross-linkable hole injection monomer VB-DATA derived from famous m-MTDATA as core peripherally functionalized with styryl (vinylbenzene) moiety as polymerizable group has been synthesized and characterized. The propensity of VB-DATA thin films formation is sensitive to the nature of solvent, in which the dichloroethane solution gave smooth polymeric thin films with surface roughness of RMS similar to 0.84 nm by spin-casting followed by thermal treatment at 190 degrees C. The introduction of oxygen-linked vinylbenzene group shifted HOMO energy level of VB-DATA to -5.1 eV along with good nondispersive hole transport property (mu h similar to 10(-6) cm(2) V-1 s(-1)) makes it suitable for serving as HIL on top of ITO electrode. The replacement of PEDOT:PSS by thermally cross-linked VB-DATA films showed comparable OLEDs performance, giving more flexibility on material selection for future OLEDs applications, especially solution-processed ones. (C) 2012 Elsevier B.V. All rights reserved.