Organic EL Display Pixel Hole Injection Layer Segmentation
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Solution Overview
Problem
Carrier leakage between adjacent pixels in organic EL display devices leads to reduced display characteristics such as luminance, contrast, and color purity, due to the sharing of conductive materials across multiple pixels.
Innovation Solution
The formation of a non-existent region or a thinner layer in the organic material layer, specifically in the hole injection layer, within the effective region of each pixel, which is achieved by depositing a deposition material via a mask with an opening, effectively suppressing carrier leakage between adjacent pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conductive material is provided common to multiple pixels in the organic material layer, then the manufacturing process is simplified and productivity is improved, but carrier leakage occurs between adjacent pixels causing deterioration of display characteristics
Solution Approach 1:
The patent applies segmentation by dividing the organic material layer into pixel-specific regions. The hole injection layer is formed with openings that correspond to each pixel's effective region, creating isolated conductive pathways. This segmentation prevents carrier leakage between adjacent pixels while maintaining the common electrode structure, thus resolving the contradiction between manufacturing simplicity and display quality.
Solution Approach 2:
The patent implements local quality by varying the presence and configuration of the hole injection layer across different regions. In the effective region of each pixel, the hole injection layer is formed with specific openings to allow carrier injection. In the non-effective region (bank area), the hole injection layer is omitted or has different characteristics. This localized differentiation prevents carrier leakage at pixel boundaries while maintaining efficient carrier injection within each pixel.
2Device complexity
If the organic material layer is formed commonly across multiple pixels, then device complexity is reduced, but carrier leakage causes loss of energy and reduced luminous efficiency
Solution Approach 1:
The hole injection layer is segmented into discrete regions aligned with each pixel's effective area. The layer includes openings that confine carriers within their respective pixel regions, preventing energy-wasting leakage to adjacent pixels. This segmentation maintains relatively simple device structure while eliminating energy loss through carrier leakage.
Solution Approach 2:
The hole injection layer acts as an intermediary component that mediates between the common lower electrode and the organic material layers. By strategically positioning openings in this intermediate layer, carriers are guided into the correct pixel regions, preventing energy loss while maintaining the simplicity of having a common electrode structure across all pixels.
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 configuration enhances display characteristics by reducing carrier leakage, thereby improving luminance, contrast, and color purity, and maintaining high luminous efficiency for each pixel.
Implementation Method 1
a first layer included in the organic material layer is formed by depositing a deposition material via a mask having an opening
Data Source
AI summary
An organic EL display device according to an embodiment of the present invention includes: a base material; a plurality of pixels located on the base material; a lower electrode included in each of the plurality of pixels; a bank defining the plurality of pixels; an organic material layer disposed on the lower electrode and on the bank and including a plurality of layers; and an upper electrode disposed on the organic material layer. In a first layer included in the organic material layer, a non-existent region where the first layer is cut off or has a thickness thinner than that of another region is formed, and the non-existent region is formed in at least a portion of an effective region of the pixel surrounded by the bank.