OLED Inkjet Printing Uniformity via Ashing and Lyophobic Layer

The patent applies preliminary action by performing an ashing treatment on the pixel defining layer before inkjet printing. This pre-treatment modifies the surface properties of the pixel defining layer to reduce the pinning effect on the contact line, thereby preventing the coffee ring effect from occurring during the subsequent ink drying process. The ashing treatment creates a more uniform surface that allows for even solvent evaporation and uniform thin film formation.

The patent changes the surface parameters of the pixel defining layer through ashing treatment. This treatment alters the surface energy, roughness, and chemical composition of the pixel defining layer, transforming it from a state that promotes contact line pinning to one that allows contact line retraction. This parameter change eliminates the conditions necessary for coffee ring effect formation while maintaining the pixel defining layer's ability to contain the ink droplet.

The ashing treatment is applied as a preliminary action to modify the pixel defining layer surface before ink deposition. This pre-treatment creates a surface that does not strongly pin the contact line, allowing the contact line to retract inward during drying. This prevents the progressive accumulation of solute at the edge that would otherwise occur due to continuous contact line pinning and capillary compensation flow.

The patent converts the potentially harmful pinning effect into a beneficial retraction effect. By modifying the pixel defining layer surface through ashing, the originally harmful strong pinning that causes edge accumulation is transformed into a controlled retraction behavior. The contact line now moves inward during drying, distributing solute more uniformly across the pixel area rather than accumulating at the edges.

The ashing treatment changes the surface parameters of the pixel defining layer to achieve a balance between lyophobic properties and contact line behavior. The treatment modifies surface energy and roughness to maintain ink isolation between pixels while reducing the excessive pinning effect. This creates an optimal surface state that prevents both ink mixing and coffee ring effect formation simultaneously.

The patent applies local quality by creating a pixel defining layer surface with spatially varying properties through ashing treatment. The surface is modified to have appropriate lyophobic characteristics at the pixel boundaries for ink containment, while the overall surface properties are adjusted to reduce contact line pinning. This local differentiation allows the structure to simultaneously achieve ink isolation and uniform thin film formation.