OLED Peripheral Partition Wall Adhesion via Local Quality Passivation
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Solution Overview
Problem
In organic light emitting diode displays, the thick pixel-area passivation layer and pixel partition wall can cause stress leading to detachment of the peripheral partition wall from the common voltage line, resulting in short-circuits and abnormal heating due to inadequate adhesive force and solvent evaporation during curing.
Innovation Solution
A structure is implemented where the peripheral passivation layer has a smaller thickness than the pixel-area passivation layer, with a tapered edge and a thicker peripheral partition wall positioned between the common voltage line and the pixel area, enhancing adhesive force and preventing lifting of the partition wall, while ensuring the common electrode does not overlap the common voltage line to avoid short-circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a thick pixel-area passivation layer and pixel partition wall are used, then the adhesive force is improved, but stress is generated leading to detachment of the peripheral partition wall
Solution Approach 1:
The patent applies different thicknesses of passivation layers in different regions: a first thickness in the pixel area and a second (smaller) thickness in the peripheral area. This local differentiation allows the pixel-area passivation layer to provide sufficient adhesive force while the peripheral passivation layer reduces stress accumulation, preventing detachment of the peripheral partition wall.
2Stability of the object's composition
If the peripheral partition wall is made thinner, then the stress is reduced, but the adhesive force decreases leading to lifting
Solution Approach 1:
The patent implements a peripheral passivation layer with a second thickness that is smaller than the first thickness in the pixel area. This local quality adjustment reduces stress in the peripheral region while maintaining sufficient adhesive force through optimized layer composition and interface design, preventing both detachment and lifting.
3Ease of manufacture
If the common electrode overlaps the common voltage line, then the manufacturing is simplified, but short-circuits occur
Solution Approach 1:
The patent extracts or removes the overlapping region between the common electrode and common voltage line by designing the common electrode to be positioned only in the pixel area, excluding the peripheral area where the common voltage line is located. This spatial separation eliminates the risk of short-circuits while maintaining manufacturing feasibility through standardized fabrication processes.
4Strength
If a thick organic layer is used, then the adhesive force is improved, but solvent evaporation during curing causes detachment
Solution Approach 1:
The patent applies a thickness gradient to the organic light emission layer: a first thickness in the pixel area and a second (smaller) thickness in the peripheral area. This local differentiation maintains sufficient adhesive force in the pixel area while reducing solvent evaporation effects in the peripheral area, preventing detachment of the partition wall from the common voltage line.
Data Source
AI summary
An organic light emitting display device comprises a common voltage line formed over a peripheral region of a substrate; a passivation layer formed over a pixel region of the substrate and the peripheral region; pixel electrodes formed over the pixel region; and a pixel defining layer formed over the pixel region and the peripheral region. The pixel defining layer defines pixel openings overlapping the pixel electrodes, respectively. The device further comprises organic light emitting layers formed over the pixel region, and disposed in the pixel openings and over the pixel electrodes, respectively; and a common electrode formed over the pixel and peripheral regions. The common electrode is disposed over the pixel defining layer and the organic light emitting layers. The common electrode contacts the common voltage line. The passivation layer comprises a portion overlapping the common voltage line but not overlapping the pixel defining layer.