Organic Electronic Substrate Asymmetric Layer Design
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Solution Overview
Problem
Conventional organic electronic devices (OEDs) face issues with light trapping due to refractive index mismatches between layers, leading to low light emission efficiency, and are prone to degradation from external environmental factors like moisture and oxygen, which affects durability.
Innovation Solution
A substrate structure for OEDs is designed with an optical functional layer having a smaller projected area than the base layer, and an electrode layer with a larger projected area, where the electrode layer is formed on the base layer without the optical functional layer, and includes a conductive material or intermediate layer to control resistance and prevent exposure to external environments, enhancing durability and light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the substrate is formed with conventional glass and standard layer structure, then the device structure is simple, but light extraction efficiency is low due to total internal reflection at interfaces
Solution Approach 1:
A low refractive index layer is introduced between the substrate and the optical functional layer to serve as an optical intermediary. This layer has a refractive index lower than both the substrate and the optical functional layer, creating a gradient that reduces total internal reflection and improves light extraction efficiency without significantly complicating the manufacturing process.
2Device complexity
If the electrode layer is formed only on the optical functional layer, then the manufacturing process is simple, but the device lacks durability against external environmental factors
Solution Approach 1:
Instead of limiting the electrode layer to only the area needed for electrical function, the electrode layer is extended beyond the optical functional layer's projected area. This inverted approach uses the electrode layer as both a functional electrical component and a protective sealing layer that prevents moisture and oxygen penetration at the edges, thereby improving durability.
3Loss of energy
If the optical functional layer has the same projected area as the base layer, then the light extraction area is maximized, but the electrode layer becomes exposed to external environment causing degradation
Solution Approach 1:
The device structure employs asymmetric area relationships among layers: the optical functional layer has a smaller projected area than the base layer, while the electrode layer has a larger projected area than the optical functional layer. This asymmetric design allows the optical functional layer to maintain sufficient light extraction area while being protected by the extended electrode layer that seals the edges against environmental factors.
4Reliability
If the electrode layer is formed with larger projected area than optical functional layer, then durability is improved by sealing, but device complexity increases
Solution Approach 1:
The electrode layer is designed to perform multiple functions simultaneously: it provides electrical conduction for device operation and acts as a sealing barrier against moisture and oxygen by extending beyond the optical functional layer. This multi-functional design improves durability without requiring additional dedicated sealing layers, thereby limiting the increase in device complexity.
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
The substrate structure improves light emission efficiency by reducing light trapping and increases the durability of OEDs by preventing moisture and oxygen penetration, ensuring stable operation and maintaining surface hardness.
Implementation Method 1
the light generated in the emitting layer in the bottom emitting device is trapped at an interface between the organic layer and the first electrode layer or in the substrate due to the total internal reflection
Implementation Method 2
the indium tin oxide (ITO) generally used as the transparent electrode layer, the organic layer, and the substrate, which is conventionally formed of glass, have refractive indexes of approximately 2.0, 1.8, and 1.5, respectively
Data Source
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AI summary
Provided are a substrate for an organic electronic device (OED), an organic electronic system, a method of manufacturing the substrate or the system, and lighting. The substrate for an OED may be increased in durability by preventing penetration of an external material such as moisture or oxygen, and thus an organic electronic system having excellent light extraction efficiency may be formed. In addition, since the substrate may be stably attached to an encapsulating structure sealing the organic electronic system, the device may have excellent durability with respect to abrasion of an electrode layer or pressure applied from an external environment. In addition, a surface hardness of an external terminal of the organic electronic system may be maintained at a suitable level.