Pixel Defining Layer Segmentation for OLED Transfer Efficiency
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Solution Overview
Problem
The existing methods for fabricating organic light emitting display devices using laser induced thermal imaging (LITI) face challenges such as high transfer energy leading to organic layer degradation, open defects, and short circuits between electrodes due to uneven pixel defining layers, particularly when using organic materials, and inorganic materials fail to fill via holes effectively.
Innovation Solution
The solution involves forming a pixel defining layer with a combination of an inorganic layer and an organic layer, where the inorganic layer is thinly formed to prevent cracking and the organic layer is used to fill the via holes, reducing the height difference between the pixel defining layer and the first electrode, thereby enhancing transfer efficiency and preventing short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the pixel defining layer is formed to a thickness of 0.5 to 1 μm using organic material, then the via holes can be filled, but the height difference between the pixel defining layer and the first electrode increases, causing high transfer energy and organic layer degradation
Solution Approach 1:
The pixel defining layer is divided into two segments: an inorganic layer (first pixel defining layer) and an organic layer (second pixel defining layer). The inorganic layer is formed thinly (500-1000 Å) to minimize height difference, while the organic layer is formed to fill the via holes. This segmentation allows each layer to perform its specific function without compromising the other, resolving the contradiction between via hole filling and height difference reduction.
Solution Approach 2:
The pixel defining layer uses a composite structure combining inorganic material (such as silicon oxide or silicon nitride) and organic material (such as polyimide). The inorganic layer provides mechanical strength and thin profile, while the organic layer provides via hole filling capability. This composite approach allows simultaneous achievement of via hole filling and minimal height difference.
2Reliability
If the pixel defining layer is formed thinly to reduce height difference, then transfer energy is reduced, but via holes are not filled effectively
Solution Approach 1:
The pixel defining layer is segmented into an inorganic layer for height control and an organic layer for via hole filling. The inorganic layer is formed to a thin thickness (500-1000 Å) to reduce height difference and transfer energy, while the organic layer is formed subsequently to fill the via holes. This sequential segmentation allows both requirements to be met.
Solution Approach 2:
The thickness parameter of the pixel defining layer is differentiated between two materials: the inorganic layer has a thickness parameter of 500-1000 Å, while the organic layer has a thickness parameter sufficient to fill the via holes. This parameter differentiation allows the thin inorganic layer to reduce height difference while the thicker organic layer fills the via holes.
3Length of stationary object
If only inorganic material is used for the pixel defining layer, then the layer can be formed thinly, but the via holes are not filled effectively
Solution Approach 1:
The pixel defining layer transitions from a single inorganic material to a composite of inorganic and organic materials. The inorganic layer (first pixel defining layer) is formed thinly (500-1000 Å) to minimize thickness, while the organic layer (second pixel defining layer) is formed to fill the via holes. This composite material approach allows the thin inorganic layer to maintain low thickness while the organic layer provides via hole filling.
4Manufacturing precision
If the pixel defining layer is formed thick to fill via holes, then via holes are filled, but the height difference increases causing open defects
Solution Approach 1:
The pixel defining layer is segmented into an inorganic layer formed to a thickness of 500-1000 Å and an organic layer formed to fill the via holes. The inorganic layer provides a thin base that minimizes height difference, preventing open defects, while the organic layer provides the necessary thickness to fill the via holes. This segmentation resolves the contradiction between via hole filling and height difference control.
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 maximizes transfer efficiency of the organic layer, reduces thermal damage, and prevents short circuits, resulting in improved reliability and screen quality of the organic light emitting display devices.
Implementation Method 1
One method of fabricating the organic layer is to use a laser induced thermal imaging (LITI) method
Implementation Method 2
transfer energy becomes high, which may stimulate degradation of the organic layer
Data Source
AI summary
An organic light emitting display device and a method of fabricating the same are provided. A trench is formed in a planarization layer, and then a first electrode is formed to have opposite ends in the trench, thereby reducing a height difference between the planarization layer and the first electrode. That is, the thickness of a pixel defining layer formed on the first electrode may be reduced by reducing or minimizing protrusion of the first electrode with respect to the planarization layer. Thus, transfer efficiency can be increased when an organic layer is formed by a laser induced thermal imaging method, and reliability of a device can be improved by reducing or preventing thermal damage of the organic layer and open defects.