OLED Electrode Contact Layout for Uniform Display Potential
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Solution Overview
Problem
Voltage drop and uneven display quality occur in light emitting devices due to resistance variations in the upper electrode, leading to deterioration of display quality such as unevenness within the light emitting surface.
Innovation Solution
A light emitting device design that includes a reflective layer between the lower electrodes, an insulating layer, and an upper electrode contact portion with a via hole for electrical connection, which stabilizes the potential distribution across the upper electrode by connecting it to the reflective layer, thereby reducing resistance variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the optical distance between the lower electrode and the reflective portion is made different for each pixel of different light emission colors, then color display quality is improved, but the upper electrode develops an uneven shape with thin film portions that increase resistance
Solution Approach 1:
The patent introduces upper electrode contact portions at specific locations (between adjacent lower electrodes or between the lower electrode and substrate) to locally compensate for voltage drops. These contact portions create localized conductive paths that counteract the uneven resistance distribution caused by the organic function film thickness variations, thereby maintaining overall electrode potential stability while preserving the color display quality achieved through differential optical distances.
2Area of stationary object
If the upper electrode is made larger to cover the entire light emitting surface, then display coverage is improved, but voltage drop increases due to resistance in the electrode material
Solution Approach 1:
The patent segments the upper electrode by introducing multiple upper electrode contact portions distributed across the light emitting surface. These contact portions act as intermediate connection points that divide the large electrode into smaller effective regions, reducing the maximum current path length and minimizing voltage drops across the entire electrode area while maintaining full surface coverage.
3Adaptability or versatility
If the film thickness of the organic function film is varied to achieve different light emission colors, then color diversity is improved, but the upper electrode becomes uneven in shape leading to high resistance
Solution Approach 1:
The patent introduces upper electrode contact portions as intermediary conductive elements that mediate between the uneven organic function film surface and the upper electrode. These contact portions provide direct conductive pathways that bypass the high-resistance thin film regions, allowing the organic function film to maintain its color-differentiating thickness variations while the upper electrode retains low overall resistance through the intermediary contact paths.
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 solution enhances display uniformity and reduces the likelihood of voltage drops, improving the overall display quality and efficiency of the light emitting device.
Implementation Method 1
an upper electrode contact portion configured to electrically connect the reflective layer and the upper electrode is arranged between the first electrode and the second electrode, and the upper electrode contact portion includes a via hole in which a conductive member configured to electrically connect the reflective layer and the upper electrode is arranged
Data Source
AI summary
Alight emitting device comprising lower electrodes arranged on a substrate, an organic layer including a light emitting layer arranged to cover the lower electrodes, an upper electrode arranged to cover the organic layer, a reflective layer arranged between the substrate and the lower electrodes, and an insulating layer arranged between the reflective layer and the lower electrodes, is provided. The reflective layer is arranged to overlap the lower electrodes. The lower electrodes include a first electrode and a second electrode adjacent to each other. An upper electrode contact portion configured to electrically connect the reflective layer and the upper electrode is arranged between the first electrode and the second electrode, and the upper electrode contact portion includes a via hole in which a conductive member configured to electrically connect the reflective layer and the upper electrode is arranged.