Top Emission OLED With Inverted Electrodes and Polygonal Buffer
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Solution Overview
Problem
The bottom emission type organic electroluminescence devices face limitations in aperture ratio and yield due to the restrictive material selection for the cathode, leading to degraded luminous efficiency and high manufacturing costs, while top emission types struggle with transmittance and luminous efficiency.
Innovation Solution
A top emission type organic electroluminescence device with a polygonal buffer structure and electrode separator to form a uniform organic electroluminescent layer, allowing for improved aperture ratio and yield by misaligning substrates and using conductive spacers for electrical connection, enabling the use of various materials for the electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If bottom emission type structure is used with traditional electrode arrangement, then the device structure is simple, but the aperture ratio is limited and material selection for cathode is restrictive
Solution Approach 1:
The patent inverts the traditional electrode arrangement by placing the cathode on the first substrate (array element substrate) and the anode on the second substrate (encapsulation substrate). This inversion allows the use of various metal materials for the cathode including aluminum, silver, and their alloys, overcoming the material selection restrictions of bottom emission type devices while maintaining structural simplicity.
2Adaptability or versatility
If top emission type structure is used to improve aperture ratio, then the aperture ratio increases, but transmittance and luminous efficiency are degraded
Solution Approach 1:
By inverting the electrode arrangement, the patent enables top emission type structure with high aperture ratio while maintaining high luminous efficiency. The inverted configuration allows light to be emitted from the top surface through the encapsulation substrate, achieving both high aperture ratio and high luminous efficiency simultaneously.
Solution Approach 2:
The patent uses composite material structures including hole injection layer, hole transporting layer, emission layer, and electron transporting layer in the organic electroluminescent layer. These composite material structures optimize both light emission efficiency and aperture ratio for top emission type devices.
3Stability of the object's composition
If bottom emission type structure is used, then the device structure is established, but the yield is limited due to foreign particles and defects in the organic electroluminescent layer
Solution Approach 1:
The patent segments the device into two separate substrates: the first substrate for array element formation and the second substrate for encapsulation. This segmentation allows independent optimization and quality control of each substrate, reducing the impact of defects and foreign particles on overall yield while maintaining structural stability.
Solution Approach 2:
The patent introduces conductive spacers as intermediary elements to electrically connect the inverted electrodes across the two substrates. These spacers facilitate reliable electrical connection while allowing independent processing and quality control of each substrate, thereby improving manufacturing yield.
4Ease of manufacture
If traditional electrode arrangement is used, then the fabrication process is established, but diverse material selection for electrodes is limited
Solution Approach 1:
The patent inverts the traditional electrode arrangement to place the cathode on the array element substrate and anode on the encapsulation substrate. This inversion enables the use of diverse metal materials including aluminum, silver, and their alloys for the cathode, while maintaining ease of fabrication through established thin film deposition processes.
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 the aperture ratio and yield of the organic electroluminescence device, allowing for high-resolution products with improved stability and design flexibility, while enabling the use of diverse materials for the electrodes, thus overcoming the limitations of both bottom and top emission types.
Implementation Method 1
an organic electroluminescence device... An organic electroluminescent layer 14 is formed on the TFT T and the first electrode 12... The first and second electrodes 12 and 16 apply an electric field to the organic electroluminescent layer 14
Data Source
AI summary
An organic electroluminescence device includes a buffer formed in a polygonal structure corresponding to each of sub-pixels, an electrode separator formed along an outer periphery of the buffer so as to separate the sub-pixels, an emission region formed in an inner region defined by the buffer, and an electric connection region formed in a region protruding from one side of the buffer.