OLED Resonance Structure Enhances Light Extraction
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Solution Overview
Problem
Conventional organic light-emitting devices face challenges in achieving high photoluminescence efficiency and uniform light extraction due to limitations in their structural design, particularly with single pixel electrodes and manufacturing processes that result in non-uniform light emission and reduced color purity.
Innovation Solution
The use of two pixel electrodes with a resonance structure, where the second pixel electrode has a higher resistance value and is directly in contact with the first pixel electrode, forming a resonance structure that enhances light emission efficiency, and a method of manufacturing involving a first and second bank with the same organic material to suppress light emission at the edges, improving light extraction quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single pixel electrode is used in conventional organic light-emitting devices, then the device structure is simple, but the photoluminescence efficiency is low and light extraction is non-uniform
Solution Approach 1:
The single pixel electrode is segmented into two distinct electrodes: a first pixel electrode and a second pixel electrode. The first electrode serves as the primary electrode, while the second electrode is positioned to overlap with the first and is electrically connected through an opening in the bank structure. This segmentation enables the formation of a resonance cavity that enhances photoluminescence efficiency and achieves uniform light extraction across the display area.
2Productivity
If the second pixel electrode has higher resistance value, then the resonance structure is enhanced for better light emission efficiency, but the electrical conductivity decreases
Solution Approach 1:
The second pixel electrode is designed with spatially varying properties: it has a higher resistance value in regions where it overlaps with the first electrode to enhance the resonance effect and light emission efficiency, while maintaining electrical connection through a controlled opening in the bank. This local quality variation allows the electrode to simultaneously achieve both high light emission efficiency and sufficient electrical conductivity where needed.
3Ease of manufacture
If printing manufacturing method is used, then the manufacturing process is simplified, but light emission at edges becomes non-uniform reducing light extraction quality
Solution Approach 1:
The bank structure is designed with a pre-defined opening pattern before the printing manufacturing process. This preliminary structure guides the printing deposition to occur only in the desired pixel regions, preventing material accumulation at edges. By establishing this structural framework in advance, the method achieves uniform light extraction while maintaining the simplicity of the printing manufacturing process.
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 described configuration improves photoluminescence efficiency and light extraction quality by forming a resonance structure between the pixel electrodes, reducing non-uniform light emission and enhancing color reproduction, while the manufacturing method ensures consistent light emission patterns.
Implementation Method 1
the first pixel electrode and the second pixel electrode forming thereby a resonance structure such that light emission efficiency of the organic light emitting device is improved
Data Source
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AI summary
An organic light-emitting device includes a first pixel electrode (120) disposed on a substrate (110), a first bank (140) covering an edge of the first pixel electrode, the first bank having a first opening exposing a portion of the first pixel electrode, a second pixel electrode (150) covering the exposed portion of the first pixel electrode through the first opening, the second pixel electrode covering at least a portion of the first bank, an organic light-emitting layer (160)covering the second pixel electrode, and an opposite electrode (170) covering the organic light-emitting layer.