OLED Substrate Assembly via Non-Light-Emitting Electrode Connection
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Solution Overview
Problem
Conventional organic light emitting devices (OLEDs) face challenges in achieving high aperture ratio and reliability due to the direct contact of electrical connecting units with the light-emitting regions during substrate assembly, leading to damage and reduced yield rates.
Innovation Solution
The solution involves assembling a first substrate with transistors and a second substrate with sub-pixels, where a first connecting electrode on the first substrate is electrically connected to a second connecting electrode in the non-light-emitting region of the second substrate, which projects towards the first substrate, ensuring electrical connection without direct contact in the light-emitting regions, thus preventing damage and improving assembly accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrical connecting units directly contact light-emitting regions during substrate assembly, then electrical connection is achieved, but the light-emitting device is damaged and yield rate is lowered
Solution Approach 1:
A non-light-emitting region is introduced as an intermediary zone between the light-emitting region and the electrical connecting units. This region serves as a buffer zone where electrical connections can be made without directly contacting the fragile light-emitting organic layers, thus preventing damage while maintaining electrical connectivity.
Solution Approach 2:
The substrate is segmented into distinct functional regions: light-emitting regions for optical output and non-light-emitting regions for electrical connections. This spatial segmentation allows independent optimization of each region's function, protecting the light-emitting regions from mechanical damage during assembly while ensuring reliable electrical connectivity through the non-light-emitting regions.
2Reliability
If electrical connecting units contact light-emitting regions, then electrical connection is established, but aperture ratio is reduced
Solution Approach 1:
The substrate surface is divided into light-emitting regions that contribute to aperture ratio and non-light-emitting regions that accommodate electrical connecting units. By confining electrical connections to non-light-emitting regions, the light-emitting regions can be maximized in area, thereby increasing the aperture ratio while maintaining necessary electrical connectivity.
3Device complexity
If TFT and light emitting device are fabricated on the same substrate, then integration is achieved, but yield rate is reduced due to multiplicative yield calculation
Solution Approach 1:
The device fabrication is segmented into two independent processes: TFT fabrication on a first substrate and light-emitting device fabrication on a second substrate. Each process can be optimized and controlled independently, and their respective yield rates are not multiplicatively combined in the same way as simultaneous fabrication, thereby improving overall yield rate while maintaining integration through subsequent assembly.
Solution Approach 2:
Non-light-emitting regions serve as intermediary zones that facilitate the connection between separately fabricated TFT substrate and light-emitting device substrate. These regions enable electrical connectivity between the two independently fabricated components without requiring direct contact that would compromise either component's integrity.
Data Source
AI summary
An organic light emitting device is formed by assembling a first substrate and a second substrate. The second substrate includes several sub-pixels. The first substrate includes several transistors and, for each subpixel, a first connecting electrode. The transistors are electrically connected to each other, and the first connecting electrode is electrically connected to the respective one of the transistors. Each sub-pixel includes a light-emitting region and a non light-emitting region. A second connecting electrode is formed within the non light-emitting region and projects toward the first substrate. The first and second substrates are electrically connected via the connection of the first and second connecting electrodes.