OELD Shielding Pattern and Substrate Segmentation for Aperture Ratio
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Solution Overview
Problem
Existing organic electroluminescent display (OELD) devices face reduced production efficiency due to the formation of both switching and driving thin film transistors and organic emitting diodes on the same substrate, leading to defects and a low aperture ratio, which hinders high resolution and efficiency.
Innovation Solution
The OELD device is designed with thin film transistors on one substrate and organic emitting diodes on another, along with a shielding pattern and separator to enhance light emission directionality and prevent current leakage, allowing for improved aperture ratio and production efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If both switching and driving thin film transistors and organic emitting diodes are formed on the same substrate, then device integration is achieved, but production efficiency decreases and defect rate increases
Solution Approach 1:
The patent divides the device into two separate substrates: a first substrate containing switching and driving thin film transistors, and a second substrate containing organic emitting diodes. This segmentation allows independent fabrication and quality control of each substrate, improving production efficiency while maintaining device integration through subsequent assembly.
2Device complexity
If both switching and driving thin film transistors and organic emitting diodes are formed on the same substrate, then device integration is achieved, but defect rate increases
Solution Approach 1:
By segmenting the device into two separate substrates, the patent enables independent fabrication processes and quality control for each substrate. This reduces the risk of defects propagating across the entire device and allows for better yield management.
Solution Approach 2:
The patent extracts the organic emitting diodes from the transistor substrate and places them on a separate second substrate. This extraction isolates the light-emitting components from the transistor components, reducing the overall defect rate by preventing defect propagation between different device types.
3Illumination intensity
If transparent material is used for the first electrode to enable light transmission, then bottom emission is achieved, but aperture ratio decreases
Solution Approach 1:
The patent inverts the traditional bottom-emission structure by making the second substrate (containing the organic emitting diodes) transparent to light. This allows light to be emitted from the top while maintaining a high aperture ratio, as the transparent second substrate does not block light transmission.
Data Source
AI summary
An electroluminescent display device includes first and second substrates facing each other and having a pixel region and a non-pixel region; a thin film transistor and an array layer on an inner surface of the first substrate; a first electrode on an inner surface of the second substrate; a buffer layer on the first electrode in the non-pixel region; a shielding pattern on the buffer layer; a separator on the shielding pattern; an emitting layer on the first electrode in the pixel region; a second electrode on the emitting layer; and a connection electrode between the first and second substrates.