OLED Light Extraction via Corrugated Structure Transfer
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Solution Overview
Problem
The existing OLED devices suffer from low light extraction efficiency due to total internal reflection and waveguide effects caused by differences in refractive indices between layers, resulting in only about 20% of generated light being emitted, while 80% is lost due to internal reflection and trapping.
Innovation Solution
An OLED device with a corrugated structure transferred from an internal light extraction layer, featuring a matrix layer with scattering particles and irregular voids, and a filling layer to reduce surface roughness, optimizing the aspect ratio of convex and concave portions to enhance light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a planar structure is used in OLED devices, then the device structure is simple and easy to manufacture, but light extraction efficiency is low due to total internal reflection and waveguide effects
Solution Approach 1:
The patent introduces a corrugated structure with periodic convex and concave patterns into the OLED device. This curvature modification changes the optical path of generated light, reducing total internal reflection at interfaces and minimizing waveguide effects. The corrugated structure causes light to undergo multiple reflections and scattering events, increasing the probability of light extraction from the device.
2Illumination intensity
If the refractive index difference between layers is maintained, then the optical contrast is good, but total internal reflection occurs at interfaces causing light loss
Solution Approach 1:
The patent adds a periodic corrugated structure that introduces spatial variation in the vertical dimension. This dimensional change creates additional optical paths and interfaces where light can be extracted. The periodic modulation of the corrugated structure causes light to interact with multiple interfaces at different angles, reducing the impact of total internal reflection while maintaining the refractive index difference for optical contrast.
3Loss of energy
If a corrugated structure is introduced to improve light extraction, then light extraction efficiency increases, but the device structure becomes more complex
Solution Approach 1:
The patent incorporates the corrugated structure during the manufacturing process itself, forming it as an integral part of the OLED device architecture. By pre-forming the corrugated pattern in the substrate or buffer layer before depositing subsequent layers, the light extraction enhancement is achieved without requiring additional complex components or post-processing steps, thus minimizing device complexity while maintaining improved light extraction efficiency.
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 significantly improves light extraction efficiency by minimizing waveguide and surface plasmon modes, leading to superior luminance efficiency by controlling the aspect ratio of the corrugated structure and scattering properties.
Implementation Method 1
total internal reflection originating from the difference in refractive indices between the glass substrate and ambient air
Implementation Method 2
The light extraction efficiency of an OLED device depends on the refractive indices of OLED layers
Implementation Method 3
a corrugated structure transferred from an internal light extraction layer is optimized to significantly increase light extraction efficiency
Implementation Method 4
OLEDs are self-emitting light sources based on the radiative decay of excitons generated in an organic light-emitting layer by the recombination of electrons injected through an electron injection electrode (cathode) and holes injected through a hole injection electrode (anode)
Data Source
Figure 1~2
Figure 3~5
AI summary
The present invention relates to an organic light emitting diode, and more specifically, to an organic light emitting diode capable of significantly increasing light extraction efficiency through optimization of a corrugated structure, which is formed by being transferred from an inner light extraction layer, thereby enabling excellent light-emitting efficiency. To this end, provided in the present invention is the organic light emitting diode comprising: a first substrate; the inner light emitting layer formed on the first substrate; a first electrode formed on the inner light emitting layer; an organic light emitting layer formed on the first electrode; and a second electrode formed on the organic light emitting layer, wherein corrugation is formed on the surface of the inner light emitting layer, wherein the corrugation is sequentially transferred onto the first electrode, the organic light emitting layer, and the second electrode, and wherein the surface of the second electrode comprises the corrugated structure, wherein the corrugated structure comprises a plurality of convex portions and a plurality of concave portions, which are formed between the convex portions that are adjacent, and wherein the depth/pitch ratio with respect to the pitch between the convex portions that are adjacent and the depth of the concave portions is 0.1 to 7.