Top-Emitting OLED Composite Cathode for High Aperture Ratio
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Solution Overview
Problem
High-resolution OLED displays face challenges in achieving a high aperture ratio and light transmission ratio due to the large area occupied by thin film transistors (TFTs), which limits their brightness and displaying effectiveness.
Innovation Solution
A composite transparent cathode structure is introduced, comprising a semi-transparent metal layer and a mesh-shaped current collection layer, along with an optical anti-reflection layer, to enhance light transmission and current conductivity while maintaining a high aperture ratio, allowing light emission from the top portion of the OLED.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If thin film transistors (TFTs) are disposed in each pixel unit to control current for high-resolution displaying, then the displaying resolution is improved, but the aperture ratio and light transmission ratio become rather low
Solution Approach 1:
The patent extracts the current control function from the pixel unit by introducing a separate current control electrode that extends across multiple pixel units. This allows the removal of individual TFTs from each pixel, freeing up area while maintaining current control capability through the shared electrode structure.
Solution Approach 2:
The current control electrode serves multiple functions: it controls current for multiple pixel units simultaneously, acts as an electrode for light emission, and provides structural support. This multi-functionality reduces the need for separate components, thereby increasing the aperture ratio while maintaining displaying resolution.
2Area of stationary object
If the area of TFTs is reduced to increase aperture ratio, then the aperture ratio is improved, but the manufacturing difficulty increases due to the small pixel unit area
Solution Approach 1:
The patent segments the current control function from the pixel structure by introducing a separate current control electrode that operates independently from the pixel-defining TFTs. This segmentation allows for larger pixel areas while maintaining precise current control, reducing manufacturing difficulty.
Solution Approach 2:
The current control electrode extends in a dimension that spans multiple pixel units, changing the spatial arrangement from localized (within each pixel) to extended (across multiple pixels). This dimensional change allows for larger aperture ratios while maintaining current control precision.
3Illumination intensity
If a transparent electrode is used to allow light emission from the substrate side, then the light transmission is improved, but the current conducting capability becomes insufficient
Solution Approach 1:
The patent employs a composite electrode structure combining transparent conductive materials with semi-transparent metal layers. This composite structure achieves both high light transmission and sufficient current conducting capability by leveraging the complementary properties of different materials.
Solution Approach 2:
The patent optimizes the optical and electrical parameters of the electrode by adjusting the thickness, composition, and layer structure of transparent and semi-transparent materials. This parameter optimization enables simultaneous achievement of high light transmission and adequate current conducting capability.
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 significantly increases the aperture ratio and light utilization, enabling high-resolution displays with improved brightness and displaying efficiency, while simplifying the manufacturing process and ensuring a high light transmission ratio.
Implementation Method 1
the second electrode is a composite transparent structure layer realizing light emission at a top portion. The composite transparent structure layer includes a semi-transparent metal layer and a current collection layer
Implementation Method 2
When an appropriate voltage is applied, electrons and holes are injected from the corresponding electrodes into the organic material layers, and the electrons and the holes are encountered and captured at corresponding positions during transmission, release energies, and emit lights
Implementation Method 3
A composite transparent cathode structure is introduced, comprising a semi-transparent metal layer and a mesh-shaped current collection layer, along with an optical anti-reflection layer, to enhance light transmission and current conductivity
Implementation Method 4
the current collection layer is formed on the semi-transparent metal layer and is a mesh structure
Data Source
AI summary
An organic light emitting diode (OLED) and a manufacturing method thereof are provided. The OLED includes a substrate, and a first electrode serving as an anode, an organic material layer, a second electrode serving as a cathode, and a sealing layer are formed on the substrate in sequence, and the second electrode is a composite transparent structure layer realizing light emission at the top portion. By forming the composite transparent cathode with a light-transmissive top portion, the OLED emits lights from the top portion, so as to effectively enhance a light utilization ratio and a light transmission ratio, and thus not only an aperture ratio of a display screen is enhanced, but also an excellent displaying effect is obtained. Meanwhile, by adding a mesh-shaped current collection layer on a high-resistance semi-transparent metal layer, a current conducting capability is enhanced while ensuring a high light transmission ratio, thereby effectively satisfying the demands for the top-emitting OLED, which is applicable to a double-sided display device. The OLED has a simple structure and simple and reliable manufacturing technique, which thus has a wide application prospect.