OLED Sealing Area Laser Absorption Layer
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Solution Overview
Problem
Existing OLED display manufacturing processes face challenges in reliably removing organic substances from the sealing area, which degrades the sealing member's reliability and is difficult to implement for top-emission type light emitting elements, especially due to incomplete removal with laser drilling and limitations in plasma etching.
Innovation Solution
A display device structure and manufacturing method that includes a laser absorption layer formed along the edge of the display area, allowing for precise laser irradiation to remove residual organic substances without damaging underlying layers, and a sealing area defined to prevent overlap with functional layers, using a glass frit sealing material and functional layers like hole injection/transport and electron injection/transport layers formed via solution processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a laser drilling process is used to remove organic substance from the sealing area, then the organic substance removal is attempted, but the organic material transmits the laser light rather than absorbing it, resulting in incomplete removal
Solution Approach 1:
A laser absorption layer is introduced as an intermediary substance between the laser beam and the organic material. This layer absorbs the laser light and converts it to thermal energy, which then heats and removes the organic substance. The absorption layer acts as a mediator that enables the laser drilling process to work effectively on materials that would otherwise be transparent to the laser wavelength.
Solution Approach 2:
The optical properties of the sealing area are changed by introducing a laser absorption layer with high absorption coefficient at the laser wavelength. This parameter change transforms the transparent/low-absorption state of the organic material to a high-absorption state through the added layer, enabling effective laser energy coupling and subsequent organic material removal.
2Ease of manufacture
If the organic material is placed over the entire area including the sealing area, then the solution process coating is simplified, but the sealing member reliability is degraded when the sealing member is placed over organic substance
Solution Approach 1:
The substrate area is segmented into a display area and a sealing area. The organic light emitting layers are selectively formed only on the display area, while the sealing area is kept free of organic material. This segmentation allows the coating process to cover the entire substrate for simplicity while preventing organic substance contamination of the sealing area through selective formation or selective removal processes.
Solution Approach 2:
The organic substance is extracted or removed from the sealing area after the overall coating process. This allows the coating process to be simplified by covering the entire area, while subsequently removing the organic material from the sealing area where it is not needed, thereby maintaining both coating simplicity and sealing reliability.
3Manufacturing precision
If a plasma etching process is used to remove organic substance, then removal capability is improved, but it is difficult to employ for top-emission type light emitting elements
Solution Approach 1:
The plasma etching process (chemical/mechanical method) is replaced with a laser-based thermal ablation process. The laser drilling process, enhanced with a laser absorption layer, uses optical energy converted to thermal energy for material removal, providing a versatile method that works for both bottom-emission and top-emission OLED structures without the limitations of plasma process geometry constraints.
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
Enhances the adhesiveness of the sealing member by ensuring complete removal of organic substances from the sealing area, improving the reliability of the sealing process and simplifying the manufacturing by using a laser absorption layer that absorbs laser energy effectively, while maintaining the integrity of the display device's functional layers.
Implementation Method 1
a laser absorption layer formed along the edge of the display area, allowing for precise laser irradiation to remove residual organic substances
Implementation Method 2
irradiating a laser to the laser absorption layer
Data Source
AI summary
A display device includes a display area and a non-display area. The non-display area includes a sealing area which includes a sealing material. The display area includes a thin film transistor structure, a pixel electrode on and connected to the thin film transistor structure, and a pixel defining layer overlapping an edge of the pixel electrode. A first functional layer is on substrate on which the pixel defining layer is formed and does not overlap the sealing area. A light emitting layer is on the first functional layer and overlaps the pixel electrode, and a common electrode on the light emitting layer.