OLED Light Extraction Substrate with Scattering Particles
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Solution Overview
Problem
The light extraction efficiency of OLED devices is significantly hindered by the waveguide effect and surface plasmon effect due to differences in refractive indices between layers, resulting in only about 20% of generated light being emitted, with the remaining 80% lost through total internal reflection and surface plasmon effects.
Innovation Solution
A light extraction substrate is manufactured by preparing a mixture of a sol-gel solution with scattering particles and a first metal oxide, coating a base substrate, firing to form a matrix layer with dispersed scattering particles, and applying a filler layer with a different refractive index to fill cracks and reduce surface roughness, creating a corrugated structure that enhances light scattering and reduces waveguide and surface plasmon effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a planar structure is used for the OLED device, then the manufacturing process is simple, but the light extraction efficiency is low due to waveguide effect and total internal reflection
Solution Approach 1:
The patent introduces a corrugated structure with periodic undulations on the substrate surface, replacing the planar geometry. This curved surface structure modifies light propagation paths, reduces waveguide effects, and enhances light extraction efficiency by preventing total internal reflection at the substrate-air interface.
Solution Approach 2:
The patent incorporates a porous layer within the OLED device structure. This porous structure increases the surface area and creates multiple interfaces for light scattering, thereby improving light extraction efficiency while maintaining a relatively simple manufacturing process.
2Loss of energy
If light extraction layers are added to improve light extraction efficiency, then more light can be extracted from waveguide mode, but the device structure becomes more complex
Solution Approach 1:
The patent combines the substrate structure with light extraction functionality by integrating the corrugated structure directly into the substrate. This merging of structural and optical functions eliminates the need for separate light extraction layers, thereby improving light extraction efficiency while avoiding increased device complexity.
Solution Approach 2:
The corrugated substrate structure serves multiple functions: it provides mechanical support, enables light extraction enhancement through reduced waveguide effects, and creates scattering centers. This multi-functionality allows the same structural element to address multiple requirements without adding additional components.
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 method significantly improves light extraction efficiency by diversifying light paths and reducing waveguide and surface plasmon effects, increasing the emitted light by up to 1.7 times compared to OLEDs without a light extraction layer.
Implementation Method 1
a number of scattering particles dispersed in the matrix layer and formed from a second metal oxide having a refractive index different from a refractive index of the first metal oxide
Implementation Method 2
The filler layer fills cracks created in the matrix layer during the firing of the mixture, and shapes of the number of scattering particles and the cracks are transferred to a surface of the filler layer
Implementation Method 3
when light exits the interior of the glass substrate, a beam of the light, having an angle of incidence greater than a critical angle, may be totally reflected and trapped inside the glass substrate
Implementation Method 4
reducing a surface plasmon effect
Data Source
AI summary
The present invention relates to a method for manufacturing a light extraction substrate for an organic light emitting diode, a light extraction substrate for an organic light emitting diode, and an organic light emitting diode comprising same, and more specifically, to a method for manufacturing a light extraction substrate for an organic light emitting diode, a light extraction substrate for an organic light emitting diode, and an organic light emitting diode comprising same, capable of significantly increasing light extraction efficiency of the organic light emitting diode. To this end, provided in the present invention is the method for manufacturing the light extraction substrate for the organic light emitting diode, comprising: a mixture-preparing step of preparing a mixture by mixing a sol-gel solution containing a first metal oxide, and a plurality of scattering particles composed of a second metal oxide having a refractive index different from that of the first metal oxide; a mixture coating step of coating the mixture on a base substrate; a mixture firing step of firing the mixture which has been coated to form, on the base substrate, a matrix layer comprising the first metal oxide and inside of which the scattering particles are dispersed; and a filling layer forming step of forming a filling layer by filling the surface of the matrix layer with a material having a refractive index different from that of the matrix layer, wherein the filling layer fills cracks formed on the matrix layer when firing the mixture, and wherein corrugation is formed on the surface of the filling layer by the scattering particles and the shape of the cracks which is transferred onto the surface of the filling layer.