OLED Pin Hole Repair via Laser Exposure and Coating
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Solution Overview
Problem
Conventional OLED displays with a bottom light emitting structure face manufacturing issues due to potential short-circuits caused by pin holes formed between the source/drain electrodes and the second electrode during the manufacturing process, which can lead to reduced yield and performance.
Innovation Solution
A method involving the formation of a pin hole opening using a laser to expose the source or drain electrodes, followed by filling this opening with a coated organic material that protrudes from the pixel defining layer, thereby preventing short-circuits between the electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a pixel defining layer is formed to define pixel regions in a bottom light emitting OLED display, then the structure can support the bottom light emitting configuration, but pin holes may form in the pixel defining layer causing short-circuits between electrodes
Solution Approach 1:
The patent applies preliminary action by forming a protective coating layer on the pixel defining layer before completing the electrode formation. This coating layer is applied in advance to prevent pin hole formation during subsequent manufacturing steps, thereby maintaining electrode insulation integrity while enabling bottom light emitting structure fabrication.
Solution Approach 2:
The protective coating layer serves as a cushioning measure applied beforehand to compensate for potential pin hole formation. This layer provides a safety barrier that prevents direct contact between electrodes even if pin holes occur in the pixel defining layer, thus resolving the contradiction between manufacturing ease and reliability.
2Device complexity
If the pixel defining layer is made thin to allow light emission from the bottom, then manufacturing is simplified, but pin holes are more likely to form causing short-circuits
Solution Approach 1:
The patent applies local quality by adding a protective coating layer specifically at locations where pin holes are likely to form in the pixel defining layer. This localized protection maintains the overall thin structure for light emission while providing enhanced precision control at critical areas prone to defects.
Solution Approach 2:
The solution uses composite materials by combining the pixel defining layer with an additional protective coating layer. This composite structure maintains the thin profile needed for bottom light emission while the coating material provides enhanced defect prevention, resolving the contradiction between device complexity and manufacturing precision.
3Productivity
If pin holes are left unfilled in the pixel defining layer, then the manufacturing process is faster, but short-circuits occur between source/drain electrodes and the second electrode
Solution Approach 1:
The protective coating layer is applied preliminarily during the manufacturing process, allowing for efficient production while simultaneously preventing short-circuits. This preliminary application resolves the contradiction by addressing the insulation issue without requiring additional time-consuming filling steps.
4Reliability
If a coated portion is added to fill pin hole openings, then electrode insulation is improved, but the device structure becomes more complex
Solution Approach 1:
The coated portion is applied locally only where pin holes exist in the pixel defining layer, rather than uniformly across the entire device. This localized approach improves electrode insulation integrity while minimizing the increase in device structure complexity, as the coating is confined to specific defect areas.
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 approach effectively addresses the issue of pin hole formation, enhancing the manufacturing yield and maintaining the integrity of the OLED display's bottom light emitting structure by preventing unwanted short-circuits and ensuring consistent performance.
Implementation Method 1
forming a pin hole opening by opening the pin hole to expose at least one of the source electrode and the drain electrode
Implementation Method 2
filling the pin hole opening with a coated portion
Data Source
AI summary
An organic light emitting diode (OLED) display includes a first electrode, an organic emission layer positioned on the first electrode, and a second electrode positioned on the organic emission layer. The OLED display includes a substrate, a thin film transistor including an active layer positioned on the substrate, a gate electrode positioned on the active layer and formed with the same layer as the first electrode, and a source electrode and a drain electrode positioned on the gate electrode and connected to the active layer, a pixel defining layer positioned between the source electrode and the drain electrode, and the second electrode, the pixel defining layer including a pixel opening exposing the first electrode and a pin hole opening exposing at least one of the source electrode and the drain electrode; and a coated portion filling the pin hole opening.