Light Extraction Substrate for OLEDs via Crack Network Electrodes
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Solution Overview
Problem
Current OLED devices suffer from low light extraction efficiency and luminance uniformity due to total internal reflection and waveguide effects caused by refractive index differences between layers, and conventional internal light extraction methods lead to cracking and increased processing costs.
Innovation Solution
A method of manufacturing a light extraction substrate involving a mixture of scattering particles with an inorganic binder, where the particles have a refractive index difference of 0.3 or greater, forming a buffer layer, and depositing metal within cracks to create a random network structure for improved light extraction and electrode formation without additional processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a planar internal light extraction layer is formed using conventional methods, then the structure is simple, but light extraction efficiency is low due to total internal reflection and waveguide effects
Solution Approach 1:
The patent applies curvature by forming convex and concave curved surfaces on the internal light extraction layer. These curved surfaces scatter light effectively, reducing total internal reflection and waveguide effects. The curvature radius is specifically controlled (1-10 μm for convex, 1-20 μm for concave) to optimize light extraction while maintaining structural feasibility.
Solution Approach 2:
The patent replaces conventional mechanical patterning methods with a chemical etching process using a mixed solution of ammonium bifluoride and hydrofluoric acid. This chemical approach creates the desired curved surface structures more effectively, achieving better light extraction efficiency without complex mechanical intervention.
2Loss of energy
If the internal light extraction layer is formed to improve light extraction efficiency, then luminous efficiency improves, but the manufacturing process becomes more complex and costly
Solution Approach 1:
The patent combines the internal light extraction layer formation with the existing OLED manufacturing process by integrating the curved surface etching step into the standard fabrication sequence. The etching process is performed on the same substrate after depositing the light extraction layer material, merging multiple functions into a unified manufacturing flow.
Solution Approach 2:
The patent optimizes specific parameters including the thickness of the internal light extraction layer (50-200 nm), the curvature radii of convex and concave surfaces, and the etching solution composition (ammonium bifluoride and hydrofluoric acid mixture). These parameter optimizations achieve high light extraction efficiency while maintaining process simplicity and cost-effectiveness.
3Loss of energy
If scattering particles with high refractive index difference are used, then light extraction efficiency improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent uses a composite internal light extraction layer consisting of scattering particles (such as TiO2, SiO2, or ZrO2 with high refractive indices) dispersed in an organic matrix material. This composite structure achieves high light extraction efficiency through the refractive index difference between particles and matrix, while the slurry formulation and firing process ensure uniform particle dispersion, maintaining 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
This approach enhances light extraction efficiency and luminance uniformity while reducing fabrication costs by forming a random network structure within the OLED device, allowing it to operate at low voltage and eliminating the need for additional planarization layers.
Implementation Method 1
a light extraction layer, through which 80% of light that would otherwise be lost in the internal waveguide mode can be extracted
Implementation Method 2
firing the mixture
Implementation Method 3
depositing metal in the cracks
Implementation Method 4
about 80% of the light generated is lost due to a waveguide effect originating from different refractive indices... as well as by the total internal reflection originating from the difference in refractive indices between the glass substrate and ambient air
Data Source
AI summary
The present invention relates to a method for manufacturing a light extraction substrate for an organic light-emitting element, a light extraction substrate for an organic light-emitting element and an organic light-emitting element comprising the same and, more specifically, to: a method for manufacturing a light extraction substrate for an organic light-emitting element, the method being capable of improving light extraction efficiency of the organic light-emitting element and also increasing luminance uniformity; a light extraction substrate for an organic light-emitting element; and an organic light-emitting element comprising the same. To this end, the present invention provides a method for manufacturing a light extraction substrate for an organic light-emitting element, comprising: a mixture preparation step of preparing a mixture by mixing a plurality of scattering particles with an inorganic binder; a mixture coating step of coating the mixture on a base substrate; a buffer layer formation step of forming a buffer layer by coating an inorganic material on the coated mixture; a calcination step of calcinating the mixture and the buffer layer; a first electrode formation step of forming a first electrode, which is made of a metal, in a crack formed in the mixture and the buffer layer in the calcination step; and a second electrode formation step of forming, on the first electrode, a second electrode electrically connected to the first electrode.