High Refractive Substrate for OLED Light Extraction
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Solution Overview
Problem
Current methods for improving light extraction efficiency in surface light emitting devices, such as OLEDs, face challenges in mass production simplicity, yield, lifespan, and reliability due to complex structures and high refractive index materials that are expensive or difficult to manufacture.
Innovation Solution
A substrate with a highly refractive layer having a light diffusion unit and a planarized surface is used between the transparent electrode and the support substrate, formed using a glass paste composite with a low-melting point glass frit, which is sintered in a vacuum or under pressure to reduce bubbles and enhance planarization, allowing for efficient light extraction and improved manufacturing yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a diffraction grid structure or lens structure is provided on the substrate to increase light extraction efficiency, then light extraction efficiency is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent changes the refractive index parameter of the substrate material to match or exceed the refractive index of the transparent electrode (e.g., using glass substrates with refractive index ≥2.0 to match ITO's refractive index of 2.0). This parameter change eliminates the need for complex diffraction grids or lens structures, as the refractive index matching alone prevents total internal reflection and improves light extraction efficiency
Solution Approach 2:
The patent replaces expensive and complex structures (diffraction grids, lens structures) with a simple, inexpensive glass substrate that has inherently high refractive index. This substitution uses a readily available material (glass) with appropriate optical properties to achieve the same light extraction function without requiring additional manufacturing steps for complex structures
2Loss of energy
If a glass substrate with high refractive index is used to increase light extraction efficiency, then light extraction efficiency is improved, but manufacturing cost increases
Solution Approach 1:
The patent selects glass substrates with specific refractive index parameters (≥2.0) that match common transparent electrodes like ITO. By changing the optical parameter (refractive index) of the substrate, the invention achieves improved light extraction efficiency using commercially available glass materials, avoiding the need for expensive specialized materials while maintaining high performance
3Productivity
If a planarized surface is formed on the substrate to improve manufacturing yield, then manufacturing yield is improved, but light extraction efficiency may be reduced
Solution Approach 1:
The patent changes the refractive index parameter of the substrate to match the transparent electrode, which eliminates the need for complex surface structures. This allows the surface to be planarized for high manufacturing yield while the refractive index matching continues to provide excellent light extraction efficiency, resolving the contradiction between surface flatness and optical performance
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
This approach increases light extraction efficiency, enhances the manufacturing yield, and improves the lifespan and reliability of surface light emitting devices by effectively planarizing the interface between the transparent electrode and the substrate, while being suitable for mass production.
Implementation Method 1
the highly refractive layer includes a light diffusion unit that diffuses light incident from the transparent electrode
Implementation Method 2
formed using a glass paste composite with a low-melting point glass frit, which is sintered in a vacuum or under pressure to reduce bubbles
Implementation Method 3
sintered in a vacuum or under pressure to reduce bubbles
Implementation Method 4
formed using a glass paste composite with a low-melting point glass frit
Data Source
AI summary
A substrate for a surface light emitting device in which a transparent electrode, an organic thin film layer, and a cathode electrode are sequentially stacked, the substrate including: a transparent support substrate; and a highly refractive layer that is disposed between the support substrate and the transparent electrode and comprises at least one layer having a refractive index that is equal to or greater than a refractive index of the support substrate, wherein the highly refractive layer comprises a light diffusion unit that diffuses light incident from the transparent electrode and a planarized surface that contacts the transparent electrode. Accordingly, a Haze value of the highly refractive layer is set to be 5% or less, and a diameter of bubbles existing in the highly refractive layer is set to be 1/10th or less of a thickness of the highly refractive layer.