Flexible OLED Substrate Composite Encapsulation for Moisture Barrier
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Solution Overview
Problem
Flexible organic light-emitting diode displays face issues with moisture permeation through defective substrates, leading to reduced lifespan and deteriorated luminance, due to the characteristics of the flexible substrate materials.
Innovation Solution
A flexible organic light-emitting display device is designed with a layered structure comprising a first polymer layer, a first transparent conductive layer, a first inorganic layer, and a plurality of pixels with an organic light-emitting diode, along with a driver to drive the diode, and includes additional layers and conductive patterns to enhance durability and prevent charge trapping, utilizing materials like polyimide and inorganic layers to improve substrate characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a flexible substrate is used to enable flexible display device, then adaptability and flexibility are improved, but moisture permeation increases leading to reduced reliability
Solution Approach 1:
The patent employs a composite encapsulation structure combining organic polymer layers (first and second polymer layers) with inorganic layers (first and second inorganic layers) to create a multi-layer barrier system. This composite structure leverages the flexibility of polymer materials while the inorganic layers provide superior moisture barrier properties, thereby maintaining flexibility while preventing moisture permeation through the flexible substrate.
Solution Approach 2:
The patent uses thin film encapsulation layers formed on the flexible substrate to create a protective barrier. The polymer and inorganic layers are deposited as thin films that conform to the flexible substrate, providing moisture protection while maintaining the overall flexibility and bendability of the display device.
2Ease of manufacture
If flexible substrate materials are used, then ease of manufacture and flexibility are improved, but charge trapping occurs leading to deteriorated luminance
Solution Approach 1:
The patent introduces a buffer layer as an intermediary component between the flexible substrate and the pixel structure. This buffer layer acts as a mediator that prevents charge trapping in the flexible substrate from affecting the organic light-emitting diode performance, thereby maintaining luminance while allowing the use of flexible substrate materials.
Solution Approach 2:
The patent extracts or removes the charge trapping problem from the flexible substrate by implementing the buffer layer and encapsulation structure, which isolate the flexible substrate's charge trapping characteristics from the active pixel components, allowing the flexible substrate to be used without compromising luminance.
3Device complexity
If simple encapsulation is used, then device complexity is reduced, but moisture permeation increases reducing lifespan
Solution Approach 1:
The patent implements a composite encapsulation system with alternating organic and inorganic layers. This multi-layer composite structure provides superior moisture barrier performance compared to simple single-layer encapsulation, thereby extending the lifespan of the display device while managing the increased complexity through systematic layer integration.
Solution Approach 2:
The encapsulation structure is segmented into multiple discrete layers (first polymer layer, first inorganic layer, second polymer layer, second inorganic layer) rather than using a single homogeneous layer. This segmentation allows each layer to provide specific functions (flexibility, moisture barrier, charge blocking) and collectively extends device lifespan through enhanced protection.
Data Source
AI summary
A flexible organic light-emitting display device may include: a first polymer layer; a first transparent conductive layer over the first polymer layer; a first inorganic layer over the first transparent conductive layer; and a plurality of pixels on the first inorganic layer and each including an organic light-emitting diode, and a driver configured to drive the organic light-emitting diode.