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 ∼0.84 nm by spin-casting followed by thermal treatment at 190 °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 (μh ∼ 10–6 cm2 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.

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► We reported a new thermally crosslinkable hole injection material for OLEDs.
► VB-DATA derived from m-MTDATA with styryl (vinylbenzene) moiety.
► After thermal polymerization, VB-DATA films displayed surface roughness of 0.84 nm.
► The replacement of PEDOT:PSS by VB-DATA showed comparable OLEDs performance.
► All solution-processed multilayer OLEDs via crosslinkable approach is possible.