Auxiliary Wiring for OLED Luminance Uniformity
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Solution Overview
Problem
Existing organic EL display devices using the top emission method face issues with non-uniform voltage distribution across light extraction electrodes, leading to variations in light emission luminance and reduced display quality due to high resistance in light transmissive conductive materials.
Innovation Solution
A display device structure with a stacked configuration of first and second electrode layers and an organic layer, where auxiliary wiring is provided between pixels to connect the second electrode layer, allowing for a larger gap between pixels and reducing the distance between light emitting elements, thereby improving luminance homogeneity and aperture ratio without increasing equipment costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a light transmissive conductive material such as ITO is used for the electrode on the light extraction side, then the aperture ratio is improved, but the resistance becomes high causing non-uniform voltage distribution and luminance variation
Solution Approach 1:
The electrode on the light extraction side is divided into multiple segments (first electrode layer and second electrode layer) with auxiliary wiring connecting them. This segmentation allows each segment to be optimized independently - the light transmissive material maintains aperture ratio while the auxiliary wiring provides additional conductive paths to ensure uniform voltage distribution across the electrode structure.
2Manufacturing precision
If individual evaporation masks are used to form pixels with different light emission colors, then color accuracy is achieved, but the manufacture tact becomes long and organic material usage increases drastically
Solution Approach 1:
Multiple pixels with different light emission colors (red, green, blue) are formed simultaneously using a single evaporation mask. The mask contains multiple opening portions that allow organic materials to be deposited in different regions in one evaporation process, eliminating the need for separate evaporation steps for each color and significantly reducing manufacturing time and material waste.
3Area of stationary object
If the gap between pixels is reduced to increase integration density, then higher resolution is achieved, but the auxiliary wiring cannot be properly formed and voltage distribution worsens
Solution Approach 1:
The auxiliary wiring is positioned in the gap region between adjacent pixels, utilizing the vertical spacing dimension rather than occupying horizontal pixel area. This allows the auxiliary wiring to be formed without reducing the gap size, maintaining both high integration density and proper voltage distribution across the electrode structure.
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 achieves more uniform light emission luminance and higher integration density without reducing the aperture ratio, simplifying the manufacturing process and reducing material usage, while maintaining high-precision dimensions and display quality.
Implementation Method 1
an organic EL display device using a self-luminous organic EL (electro luminescence) element
Data Source
AI summary
A display device includes: a pixel including a plurality of light emitting elements each formed by sequentially stacking a first electrode layer, an organic layer, and a second electrode layer, spaced apart from each other in a first direction orthogonal to the stacking direction thereof, and emitting light emission colors different from each other; and an auxiliary wiring layer electrically connected to the second electrode layer. A plurality of the pixels are aligned in the first direction so as to include a gap which is larger than a gap between the light emitting elements adjacent to each other, and the auxiliary wiring layer is provided between the pixels adjacent to each other.