Segmented Metal Nanowire Electrodes for Display Devices
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Solution Overview
Problem
In display devices with top-emission self-light-emitting elements, semi-light-transmitting metal thin films like magnesium silver alloys or light-transmitting metal oxide films for the second electrode lead to low optical transmittance and potential damage to light-emitting layers, while metal nanowires cause light scattering and color mixture.
Innovation Solution
A display device with a thin film transistor layer and a light-emitting element layer, where the second electrode consists of metal nanowires segmented by bank structures for each luminescent color to prevent light-emission degradation, improve visual angle characteristics, and avoid color mixture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a semi-light-transmitting metal thin film (magnesium silver alloy) is used for the second electrode, then the optical transmittance is improved, but light is reflected to generate a cavity effect which deteriorates visual characteristics
Solution Approach 1:
The patent segments the metal nanowire network into multiple layers with different orientations. The first metal nanowire layer has nanowires extending in a first direction, while the second metal nanowire layer has nanowires extending in a second direction different from the first direction. This segmentation reduces light reflection and cavity effects while maintaining transmittance.
2Illumination intensity
If a light-transmitting metal oxide thin film (ITO) is used for the second electrode, then the optical transmittance is improved, but the light-emitting layer is damaged in sputtering film forming which degrades light-emission characteristics
Solution Approach 1:
The patent replaces the sputtering process (mechanical/physical deposition method) with a solution-based deposition method for forming the metal nanowire layer. This substitution eliminates the damage caused by sputtering to the light-emitting layer while achieving the desired optical transmittance and electrical conductivity.
3Illumination intensity
If metal nanowires are used for the second electrode, then the optical transmittance is improved, but light emitted from the light-emitting layer is scattered by the metal nanowires to cause color mixture
Solution Approach 1:
The patent segments the metal nanowire network into multiple oriented layers. By arranging nanowires in specific directions (first direction in one layer, second direction in another layer), the scattering of light is controlled to prevent color mixture while maintaining high optical transmittance.
Solution Approach 2:
The patent applies different orientations of metal nanowires in different layers to achieve different optical properties. The first metal nanowire layer has a specific orientation optimized for certain wavelengths, while the second layer has a different orientation to complement and enhance the overall performance, reducing color mixture.
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 light extraction efficiency, maintains excellent visual characteristics, and prevents color mixture by segmenting metal nanowires with bank structures, ensuring better light-emission performance and visual quality.
Implementation Method 1
light emitted from the light-emitting layer may be scattered by the metal nanowires to cause a color mixture
Data Source
AI summary
A display device includes a light-emitting element layer including a plurality of light-emitting elements including light-emitting elements configured to emit lights of luminescent colors different from each other, each light-emitting element being provided with a first electrode, a function layer including a light-emitting layer, and a second electrode in this order, the second electrode includes metal nanowires, and the light-emitting element layer is provided with a pixel bank segmenting the metal nanowires at least for each luminescent color.