OLED Partition Geometry for Bending Reliability
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Solution Overview
Problem
Top emission type OLED devices face reliability issues due to separation of the organic emitting layer from the cathode electrode when subjected to repetitive bending, which affects the device's durability and performance.
Innovation Solution
The implementation of a partition with a smaller upper surface width than its lower surface, along with an encapsulation layer, to enhance the adhesive strength between the organic emitting layer and the cathode electrode, and the use of a partition cover with a smaller upper surface width to minimize contact with the mask and prevent contamination, thereby improving the structural integrity and reliability of the OLED device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the cathode electrode is formed of a transparent conductive material to allow light emission in top emission type OLED, then the aperture ratio is improved, but the adhesive strength between the organic emitting layer and cathode electrode deteriorates under bending stress
Solution Approach 1:
The device is divided into multiple functional layers including the cathode electrode layer, organic emitting layer, and encapsulation layer. This segmentation allows each layer to perform its specific function while maintaining overall structural integrity under bending stress, resolving the contradiction between maintaining aperture ratio and ensuring adhesive strength.
Solution Approach 2:
The cathode electrode uses a composite structure with transparent conductive material combined with other materials that provide mechanical stability. This composite approach maintains the optical transparency needed for high aperture ratio while providing sufficient adhesive strength to prevent layer separation under bending conditions.
2Ease of manufacture
If the organic emitting layer is directly deposited on the cathode electrode to simplify manufacturing, then the manufacturing process is simplified, but the structural integrity deteriorates under repetitive bending
Solution Approach 1:
The encapsulation layer is formed in advance to cover and protect the organic emitting layer before the device undergoes bending stress. This preliminary protective action ensures structural integrity is maintained while allowing the manufacturing process to remain relatively simple.
Solution Approach 2:
The encapsulation layer acts as a cushioning layer that protects the organic emitting layer from mechanical stress during bending operations. This beforehand cushioning prevents layer separation and maintains structural integrity without complicating the manufacturing process.
Data Source
AI summary
Disclosed is an organic light emitting display (OLED) device that may include a thin film transistor on a substrate; a first electrode electrically connected with the thin film transistor; an organic emitting layer on the first electrode, the organic emitting layer separated by a partition; a partition cover on the partition; a second electrode on the organic emitting layer; and an encapsulation layer on the second electrode, wherein a width of an upper surface of the partition cover is smaller than a width of a lower surface of the partition cover.