OLED Pixel Encapsulation Layout for Mask-Free Pattern Alignment
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Solution Overview
Problem
Current OLED display panel manufacturing technologies face challenges with high manufacturing costs due to expensive fine metal masks and issues with light emitting pattern oxidation, leading to low production yield and inability to achieve high-resolution patterns.
Innovation Solution
The display panel design incorporates a driving circuit layer with light emitting devices and encapsulation structures, where the light emitting pattern and second electrode extend from the pixel opening to cover the pixel definition layer, using the encapsulation structure as a hard mask to improve alignment accuracy and prevent oxidation, thereby enhancing production yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If OLED evaporation technology uses a fine metal mask to form light emitting patterns, then the light emitting patterns can be formed, but the manufacturing cost increases due to expensive fine metal masks
Solution Approach 1:
The patent extracts the light emitting pattern formation process from the expensive fine metal mask evaporation technology. Instead of using FMM to define patterns, the invention forms light emitting patterns through lithography on the entire surface of evaporated light emitting material, then selectively removes non-light-emitting portions. This eliminates the need for expensive fine metal masks while maintaining pattern formation capability.
Solution Approach 2:
The patent uses lithography to create a photomask pattern that copies the desired light emitting pattern. The photomask serves as a template that defines which areas of the evaporated organic light emitting material should emit light. This copying approach replaces the expensive fine metal mask with a cheaper photomask while achieving the same pattern definition function.
2Ease of manufacture
If OLED lithography technology is used to define light emitting patterns on the entire surface, then the manufacturing cost decreases, but the previously formed light emitting patterns are easily oxidized during manufacturing
Solution Approach 1:
The patent performs preliminary encapsulation of the light emitting patterns immediately after lithography definition. The encapsulation structure is formed before subsequent manufacturing steps, creating a protective barrier that prevents oxidation of the light emitting patterns during the manufacturing process. This preliminary protective action ensures the patterns remain functional throughout production.
Solution Approach 2:
The encapsulation structure creates an inert environment around the light emitting patterns, isolating them from oxygen and moisture during manufacturing. This protective enclosure prevents oxidation by maintaining a chemically inert atmosphere around the sensitive organic light emitting material, ensuring reliability despite the use of cost-effective lithography technology.
3Device complexity
If the light emitting pattern is formed only within the pixel opening, then the alignment is simpler, but the alignment accuracy decreases and oxidation protection is insufficient
Solution Approach 1:
The patent extends the light emitting pattern from a two-dimensional area within the pixel opening to a three-dimensional structure that covers the pixel definition layer. The light emitting pattern is formed on the first electrode and extends to cover the pixel definition layer, creating an overhang structure. This dimensional extension improves alignment accuracy by providing a larger overlap area with the pixel definition layer, ensuring precise registration even with manufacturing tolerances.
Data Source
AI summary
A display panel including a driving circuit layer, multiple light emitting devices and multiple encapsulation structures is provided. The light emitting devices are disposed on the driving circuit layer, and each includes a first electrode, a light emitting pattern, a second electrode and a pixel definition layer. The light emitting pattern is disposed on the first electrode. The second electrode is disposed on the light emitting pattern. The pixel definition layer is disposed on the driving circuit layer, and has a pixel opening overlapping the first electrode. The light emitting pattern and the second electrode cover the pixel definition layer, the first electrode located in the pixel opening of the pixel definition layer and part of the driving circuit layer located outside the pixel opening of the pixel definition layer. The encapsulation structures cover the light emitting devices and each includes a first encapsulation pattern. Edges of the first encapsulation pattern, the light emitting pattern and the second electrode overlapping with each other are aligned with each other.