Reflective Electrode Structure for OLED Light Extraction
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Solution Overview
Problem
Organic light emitting diode displays have low light extraction efficiency due to significant light loss through total reflection, with only about 20% of generated light being emitted externally, while the remaining 70% is dissipated as heat.
Innovation Solution
The formation of both a first and second electrode as reflective electrodes with inclined portions and circular arc portions to redirect light generated from the organic emission layer, allowing it to be emitted to the side rather than being lost through total reflection, thereby improving light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If both first and second electrodes are formed as reflective electrodes with inclined portions, then light extraction efficiency is improved, but device complexity increases
Solution Approach 1:
The electrode structure is segmented into multiple functional portions: a flat portion for electrical connection and light generation, and inclined portions (first and second inclined portions) for light redirection. This segmentation allows each portion to perform its specific function optimally, resolving the contradiction by making the complex structure serve multiple purposes that collectively improve light extraction efficiency.
Solution Approach 2:
The electrode transitions from a two-dimensional planar structure to a three-dimensional structure with inclined portions extending in the substrate direction. This dimensional change enables the electrode to redirect light at specific angles (30° to 75°) toward the side emission direction, improving light extraction efficiency while the inclined geometry itself becomes the solution to the complexity issue rather than an added complication.
2Illumination intensity
If light is redirected to the side through inclined electrode portions, then external light emission is enhanced, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies a range for the inclined angle (30° to 75°) rather than a single precise value. This parameter range approach allows manufacturing flexibility while still achieving the desired light redirection effect. The range accommodates normal manufacturing variations without compromising the fundamental light extraction improvement, thus resolving the contradiction between enhanced emission and precision requirements.
3Productivity
If reflective electrodes are used to extract light to the side, then light extraction efficiency improves, but energy loss as heat is reduced rather than eliminated
Solution Approach 1:
The patent converts the previously harmful total internal reflection (which caused light to be trapped and dissipated as heat) into a beneficial redirection mechanism. The inclined electrode portions are positioned and angled to intercept light that would otherwise be totally reflected, and redirect it toward side emission. This transforms the harmful waveguide phenomenon into a useful light extraction mechanism, improving efficiency while reducing heat loss.
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 reduces internal light loss, enhancing light extraction efficiency and enabling higher external light emission, while also allowing for a high-resolution design by separating emission and opening regions, thus improving the display's performance and design flexibility.
Implementation Method 1
both the first electrode and the second electrode are reflective electrodes
Implementation Method 2
An organic light emitting diode is an element using light generated when an electron and a hole are coupled with each other to emit light
Implementation Method 3
The second electrode may have an inclined portion in the substrate direction. Here, an inclined angle of the inclined portion may be 30° to 75°
Data Source
AI summary
An organic light emitting diode display and a manufacturing method thereof, and more particularly, an organic light emitting diode display having improved light extraction efficiency by forming both a first electrode and a second electrode as reflective electrodes to guide generated light to the side of a pixel, and a manufacturing method thereof.