OLED Electrode Surface Treatment for Inkjet Printing Uniformity
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Solution Overview
Problem
In OLED display manufacturing, the uniformity of functional layers formed by inkjet printing is compromised due to uniform surface affinity of electrodes, leading to dewetting and nonuniform film layers, which degrades luminous uniformity and yield.
Innovation Solution
A surface treatment method is applied to first electrodes, using a mask with a shielding layer that gradually decreases in shielding capacity or material content from the central to the peripheral part, increasing surface affinity from the center to the periphery, preventing dewetting during inkjet printing of light emitting functional layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform surface treatment is applied to electrodes, then manufacturing process is simple, but inkjet printing produces dewetting and nonuniform film layers
Solution Approach 1:
The patent applies local quality by creating a nonuniform surface treatment pattern on the electrode, where the peripheral region has higher surface energy than the central region. This is achieved by selectively exposing the electrode to plasma or UV radiation through a mask with varying transparency, resulting in different wettability characteristics across different regions of the electrode surface. This local differentiation ensures uniform inkjet printing without dewetting while maintaining manufacturing feasibility.
2Reliability
If surface affinity is increased uniformly, then ink spreadability improves, but dewetting occurs in central regions
Solution Approach 1:
The patent employs asymmetry by creating an intentional gradient in surface affinity across the electrode surface. The peripheral regions are treated to have higher surface energy and wettability, while the central region maintains lower surface energy. This asymmetric distribution prevents the ink from retracting in the center during jetting, eliminating dewetting issues while ensuring reliable ink spreadability in the peripheral regions where the functional layer is deposited.
3Productivity
If yield is improved through uniform surface treatment, then production efficiency increases, but luminous uniformity deteriorates
Solution Approach 1:
The patent resolves this contradiction by implementing local quality through spatially differentiated surface treatment. By creating a surface energy gradient where peripheral regions have higher affinity than central regions, the patent ensures uniform functional layer deposition across the entire electrode surface. This eliminates the dewetting defects that would otherwise cause luminous nonuniformity, while the selective treatment pattern maintains production efficiency by avoiding unnecessary treatment of the central region.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enhances the uniformity of film layers and luminous uniformity, improving the yield of the display substrate by ensuring better ink spreadability and adherence on the electrodes.
Implementation Method 1
shielding the first electrode layer with a mask, the mask including a shielding layer, the shielding layer including a plurality of shielding units arranged in an array in one-to-one correspondence with the plurality of first electrodes
Implementation Method 2
performing a surface treatment on the plurality of first electrodes, such that an affinity of a surface of each of the plurality of first electrodes gradually increases from a central portion of the surface to a peripheral portion of the surface
Data Source
AI summary
Embodiments of the present disclosure provide a method of manufacturing a display substrate. The method includes: forming a first electrode layer on a substrate, the first electrode layer including a plurality of first electrodes arranged in an array; performing a surface treatment on the plurality of first electrodes, such that an affinity of a surface of each of the plurality of first electrodes gradually increases from a central portion of the surface to a peripheral portion of the surface around the central portion, or the affinity of the central portion of the surface is less than the affinity of the peripheral portion of the surface; and forming a light emitting functional layer on the surfaces of the plurality of first electrodes subjected to the surface treatment. Embodiments of the present disclosure further provide a display substrate, a display panel, and a mask.