OLED Evaporation Source Angular Geometry for Uniform Organic Layer Deposition
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Solution Overview
Problem
The existing OLED display manufacturing process results in non-uniform thickness of the organic light emitting layer due to the evaporation method, leading to varying light brightness across a single pixel and color mixture issues across multiple pixels.
Innovation Solution
A method involving the formation of a pixel definition layer and a spacer on a base, with a mask plate and evaporation source configuration that ensures an acute angle between the evaporation area border and the base, preventing blockage and allowing uniform deposition of the organic light emitting layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional evaporation method is used to form the organic light emitting layer, then the manufacturing process is simple, but the organic light emitting layer has non-uniform thickness resulting in varying light brightness and color mixture
Solution Approach 1:
The pixel definition layer and spacer are formed in advance before the evaporation process. The spacer is positioned to define the evaporation area boundaries, and the pixel definition layer creates the angular geometry that prevents shadowing. This preliminary structuring ensures uniform thickness without requiring complex real-time control during evaporation.
Solution Approach 2:
The invention introduces angular geometry in the vertical dimension by designing the pixel definition layer with specific acute angles. This three-dimensional angular structure prevents shadowing effects during evaporation, allowing uniform material deposition across the pixel area without the need for complex lateral positioning systems.
2Productivity
If the evaporation source is positioned close to the substrate to improve deposition efficiency, then productivity increases, but shadowing effects from the spacer and mask plate cause non-uniform thickness
Solution Approach 1:
The pixel definition layer is designed with asymmetric angular geometry where the acute angle between its side surface and the base is specifically controlled. This asymmetric angular design ensures that the evaporation area border always has a greater angle with the base, creating a geometric relationship that prevents shadowing while allowing close positioning of the evaporation source for high productivity.
Solution Approach 2:
The invention changes the geometric parameters of the pixel definition layer and evaporation area, specifically the acute angles relative to the base. By ensuring the evaporation area border angle is greater than the pixel definition layer angle, the system achieves both close evaporation source positioning for efficiency and uniform deposition without shadowing.
3Manufacturing precision
If the acute angle of the pixel definition layer is increased to prevent shadowing, then manufacturing precision improves, but the geometric constraints become more difficult to achieve
Solution Approach 1:
The invention applies specific angular geometry only at critical locations where shadowing would occur. The pixel definition layer has acute angles at its sides that contact the spacer, while other areas maintain standard geometry. This localized angular design prevents shadowing without requiring complex geometry throughout the entire structure, easing manufacturing.
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 method ensures a uniform thickness of the organic light emitting layer, eliminating color mixture and achieving consistent light brightness across pixels.
Implementation Method 1
moving an evaporation source along a first direction parallel to the lower surface of the base, so as to form an organic light emitting layer in the pixel area
Data Source
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AI summary
The present disclosure relates to a method for manufacturing a display substrate, a display substrate and a display device. The method comprises: forming a pixel definition layer on a lower surface of a base so as to define a pixel area; forming a spacer on a lower surface of the pixel definition layer; arranging a mask plate under the spacer; and moving an evaporation source along a first direction parallel to the lower surface of the base, so as to form an organic light emitting layer in the pixel area. An acute angle between a side surface of the pixel definition layer in the first direction for defining the pixel area and the lower surface of the base is a first angle. An acute angle between a border of an evaporation area of the evaporation source in the first direction and the lower surface of the base is a second angle, wherein the second angle is greater than or equal to the first angle. When the evaporation source starts forming the organic light emitting layer in the pixel area, the spacer and the mask plate do not block a first border of the evaporation area. Further, when the evaporation source stops forming the organic light emitting layer in the pixel area, the spacer and the mask plate do not block a second border of the evaporation area.