Stable solution processed hole injection material for organic light-emitting diodes

• A new aqueous based polymer was used as hole injection layer.
• The improved injection efficiency was characterized by dark injection transient measurement.
• The air stability of this new hole injection material is better due to reduced acidity.
• A long lifetime device was demonstrated with this new material.

A new aqueous based polymer, Plexcore® OC AQ1200 (AQ1200) was used as a hole injection layer (HIL) in organic light emitting diodes (OLEDs) and the device results are compared with polyethylene dioxythiophene:polystyrene sulfonate (PEDOT:PSS) in terms of injection efficiency and stability. Dark injection transient measurements show a higher injection efficiency in hole-only devices using AQ1200 HIL compared with PEDOT:PSS. Using AQ1200 as an HIL, high efficiency phosphorescent OLEDs are demonstrated to have a long lifetime, with an estimated operational half lifetime (LT 50) of more than 8000 h from an initial luminance of 1000 cd/m2.

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