Light-emitting Display Device Bank Surface Roughness Current Leakage
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Solution Overview
Problem
Current light-emitting display devices with common layers in subpixels suffer from current leakage, leading to unintended light emission from neighboring subpixels, which deteriorates color display quality.
Innovation Solution
A light-emitting display device structure featuring a substrate with subpixels, a first electrode, a bank with increased surface roughness, a first common layer covering the electrode and bank, a light-emitting layer, and a second common layer, along with a roughness-inducing layer between electrodes to prevent current leakage, and plasma treatment on the bank to enhance surface roughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If common layers are commonly stacked in subpixels to increase light emission, then light emission intensity is improved, but current leakage occurs to neighboring subpixels causing color display deterioration
Solution Approach 1:
The patent segments the common layers into subpixel-specific layers (first common layer and second common layer) that are disposed within each subpixel rather than being shared across all subpixels. This segmentation prevents current leakage to neighboring subpixels while maintaining light emission intensity from the light-emitting layer.
2Illumination intensity
If subpixels are driven to emit light vertically, then light emission from light-emitting layer is improved, but current leaks laterally to common layers of neighboring subpixels
Solution Approach 1:
The patent applies local quality by providing different layer structures in different locations: subpixel-specific common layers are provided in emission regions to enable vertical light emission, while isolation structures are provided at boundaries to prevent lateral current leakage. This local differentiation resolves the contradiction between light emission and current leakage prevention.
3Device complexity
If common layers are provided in common in subpixels, then device structure is simplified, but neighboring subpixels emit unintended light due to current leakage
Solution Approach 1:
The patent segments the common layers into first common layers and second common layers that are disposed within each subpixel rather than being shared. This segmentation prevents unintended light emission from neighboring subpixels while maintaining relatively simple device structure through the use of standardized layer configurations.
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 effectively prevents current leakage between subpixels, ensuring independent driving of each subpixel and minimizing unintended light emission, thereby improving color display accuracy.
Implementation Method 1
a bank defining an emission part in each of the subpixels and having an upper surface that has a larger degree of surface roughness than the upper surface of the first electrode
Implementation Method 2
The upper surface of the bank may be plasma-treated
Data Source
AI summary
A light-emitting display device includes a substrate having a plurality of subpixels; a first electrode provided in each of the subpixels; a bank defining an emission part in each of the subpixels and having an upper surface that has a larger degree of surface roughness than an upper surface of the first electrode; a first common layer over the subpixels and covering the first electrode and the bank; a light-emitting layer on the first common layer and corresponding to the emission part of each of the subpixels; and a second common layer and a second electrode stacked on the light-emitting layer over the plurality of subpixels.