Organic Electronic Substrate with Particle-Containing Layer for Light Extraction
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Solution Overview
Problem
In organic electronic devices (OEDs), such as OLEDs, a significant amount of light is trapped due to the refractive index mismatch between the organic layer and the substrate, leading to low light extraction efficiency.
Innovation Solution
A substrate with a particle-containing layer comprising first and second particles of different refractive indices and sizes, along with a binder, is used to enhance light scattering and extraction, while maintaining thermal and chemical resistance, and an overcoat layer is applied to optimize refractive index and planarization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional substrate structure with uniform refractive index is used, then the device structure is simple and easy to manufacture, but light extraction efficiency is low due to total internal reflection at interfaces
Solution Approach 1:
The substrate is constructed as a composite material system consisting of a base substrate layer and a particle-containing layer. The particle-containing layer incorporates particles with refractive indices of 1.7 or higher (such as TiO2, SiO2, or ZrO2 particles) dispersed in a binder resin, creating a composite structure that combines the mechanical strength of the base substrate with the light scattering properties of the high-refractive-index particles. This composite structure effectively reduces total internal reflection and improves light extraction efficiency while maintaining manufacturing feasibility.
Solution Approach 2:
Instead of making the entire substrate uniformly complex, the invention applies the particle-containing layer only in specific regions where light extraction enhancement is needed. The particle-containing layer can be positioned adjacent to the organic light-emitting layer or distributed in specific patterns, allowing local optimization of light extraction properties without complicating the entire substrate structure. This localized approach maintains ease of manufacture while improving light extraction efficiency where it matters most.
2Reliability
If particles are added to the substrate to scatter light, then light extraction efficiency is improved, but the substrate surface becomes uneven and requires additional planarization steps
Solution Approach 1:
The invention introduces a thin film layer (such as an adhesive layer or planarization layer) with a thickness of 1 μm or less that covers the particle-containing layer. This thin film acts as a flexible shell that smooths out the surface irregularities caused by the particles while maintaining the underlying light scattering structure. The thin film approach effectively planarizes the surface for subsequent electrode and organic layer deposition without requiring complex mechanical planarization processes, thus improving light extraction efficiency while controlling device complexity.
3Reliability
If high refractive index particles are incorporated into the substrate, then light scattering is enhanced, but the manufacturing precision is reduced due to surface unevenness
Solution Approach 1:
A thin film layer with thickness of 1 μm or less is introduced to cover the particle-containing layer, effectively smoothing the surface while preserving the light scattering function of the particles beneath. This thin film acts as a flexible shell that masks surface irregularities, enabling subsequent manufacturing steps (such as electrode deposition and organic layer formation) to proceed with high precision. The thin film approach maintains the light scattering performance of the high-refractive-index particles while restoring surface flatness to acceptable manufacturing tolerances.
Solution Approach 2:
The thin film layer serves as an intermediary between the particle-containing layer and the subsequent device structures. It mediates the conflict between light scattering performance and surface flatness by providing a smooth interface for subsequent manufacturing steps while allowing the particle-containing layer to maintain its light scattering function. This intermediary layer effectively decouples the two requirements, allowing high light scattering performance without compromising manufacturing precision.
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 significantly improves light extraction efficiency and reliability of OEDs by scattering trapped light and maintaining structural integrity during manufacturing processes.
Implementation Method 1
A substrate with a particle-containing layer comprising first and second particles of different refractive indices and sizes, along with a binder, is used to enhance light scattering and extraction
Implementation Method 2
light generated in the organic emitting layer in the bottom emitting device is trapped by total internal reflection at an interface between the organic layer and the first electrode layer, or in the substrate
Data Source
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AI summary
The present application relates to a substrate for an organic electronic diode (OED), an organic electronic system, and a lighting. In the present application, the substrate capable of forming an OED or the organic electronic system can ensure performance including light extracting efficiency and reliability is provided.