Translucent Metal Auxiliary Wiring for Top-Emission OLED Brightness Uniformity
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Solution Overview
Problem
In organic electroluminescence apparatuses, the high electric resistance of the second electrode layer causes variations in brightness, particularly in top-emission devices, where the second electrode layer must be translucent, leading to reduced pixel size and aperture ratio due to the need for auxiliary wiring layers that require additional space.
Innovation Solution
A translucent auxiliary wiring layer with a stripe-like or grid-like pattern, formed from a metal layer such as silver or silver alloy, is disposed on the upper or lower side of the second electrode layer, allowing it to overlap with pixels without significantly reducing light emission, thus eliminating the need for additional space between pixels and enabling a higher pixel aperture ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the second electrode layer is made thin to achieve translucency in top-emission organic EL apparatus, then light emission is improved, but electric resistance increases causing brightness variation
Solution Approach 1:
The patent divides the auxiliary wiring into multiple stripe-like or grid-like patterns that are distributed across the pixel region. This segmentation allows the auxiliary wiring to provide electrical compensation without forming a single continuous layer that would block light, thus resolving the contradiction between translucency and electrical conductivity.
Solution Approach 2:
The auxiliary wiring is configured with varying transparency and conductivity properties in different regions. The stripe-like or grid-like pattern creates local variations where some areas have higher electrical conductivity while maintaining overall translucency, allowing targeted compensation of brightness variation without sacrificing light emission.
2Reliability
If an auxiliary wiring layer is disposed between adjacent pixels to compensate for electric resistance, then brightness uniformity is improved, but pixel size and aperture ratio decrease
Solution Approach 1:
The patent transitions from a conventional approach of placing auxiliary wiring between pixels (horizontal/vertical arrangement) to a stripe-like or grid-like pattern that overlays the pixel region. This dimensional reconfiguration allows the auxiliary wiring to function within the existing pixel area without requiring additional spacing, thus maintaining pixel size while achieving brightness uniformity.
Solution Approach 2:
The auxiliary wiring layer serves multiple functions simultaneously: it provides electrical compensation for brightness uniformity, maintains translucency for light emission, and fits within the existing pixel structure without requiring additional space. The stripe-like or grid-like pattern enables the same structure to fulfill both electrical and optical requirements.
3Object-affected harmful factors
If a light-shielding layer with large width is disposed between adjacent pixels to prevent color mixing, then color separation is improved, but pixel aperture ratio decreases due to auxiliary wiring space requirements
Solution Approach 1:
The patent combines the auxiliary wiring function with the existing light-shielding layer structure. The stripe-like or grid-like pattern of the auxiliary wiring is integrated with the light-shielding layer, allowing both color mixing prevention and electrical compensation to be achieved within the same structural framework, thus eliminating the need for additional width while maintaining both functions.
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 configuration allows for larger pixel sizes and improved light emission region ratios, resulting in higher brightness and quality color displays without the need for broad spaces between pixels, and can incorporate a half mirror layer for enhanced color purity.
Implementation Method 1
organic electroluminescence devices each having at least a first electrode layer, an emission layer, and a translucent second electrode layer stacked in this order
Implementation Method 2
an auxiliary wiring layer having a stripe-like pattern or a grid-like pattern and disposed on the upper side or the lower side of the second electrode layer so as to be in contact with the second electrode layer
Data Source
AI summary
An organic electroluminescence apparatus includes a support substrate having a pixel region; a plurality of pixels; organic electroluminescence devices each having at least a first electrode layer, an emission layer, and a translucent second electrode layer; and an auxiliary wiring layer having a stripe-like pattern or a grid-like pattern. The apparatus emits light emitted from the organic electroluminescence device from the side where the second electrode layer is disposed, the second electrode layer is disposed over the entire or approximately the entire pixel region, and the auxiliary wiring layer is formed of a metal layer having a thickness capable of achieving translucency and is disposed so as to, in the plan view, overlap at least part of the organic electroluminescence device of each of the plurality of the pixels.