Conductive Resonator Spacer Layers for Full-Color OLED Microresonators
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Solution Overview
Problem
Current organic EL display devices face challenges in achieving high display quality and stability when implementing a microresonator structure for full-color displays, as it requires complex manufacturing processes and increases production costs and variability.
Innovation Solution
A method for manufacturing a display device with a microresonator structure where a conductive resonator spacer layer made of transparent conductive metal oxide is formed between reflective films, allowing for precise adjustment of optical length for different light emission wavelengths by varying the number of layers or remaining layers of conductive metal oxide, enabling accurate light intensification in each pixel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the optical length in each pixel is adjusted by independently manufacturing pixels with different thicknesses to achieve different light emission wavelengths, then the full-color display capability is improved, but the manufacturing process complexity increases and production quality variability deteriorates
Solution Approach 1:
The conductive metal oxide layer is divided into multiple sub-layers that can be independently controlled. By selectively removing certain sub-layers in different pixel regions, the patent achieves different optical lengths for different colors (R, G, B) without requiring completely different manufacturing processes for each pixel type. This segmentation allows standardization of the base manufacturing process while enabling color-specific variations.
Solution Approach 2:
The patent applies local quality by making specific modifications to certain regions of the conductive metal oxide layer based on the required light emission wavelength. Different pixel regions (corresponding to different colors) have different numbers of conductive metal oxide layers removed, creating locally optimized optical properties while maintaining a unified overall structure and manufacturing approach.
2Adaptability or versatility
If the optical length in each pixel is adjusted by independently manufacturing pixels with different thicknesses to achieve different light emission wavelengths, then the full-color display capability is improved, but the production cost and quality variation increase
Solution Approach 1:
The patent forms all conductive metal oxide layers in advance using a standardized manufacturing process before any selective removal. This preliminary formation ensures that the base structure is consistent across all pixels, and subsequent selective removal (via etching or lifting-off) precisely adjusts the optical length without introducing additional manufacturing variability. The preliminary action establishes a reliable foundation that reduces quality variation.
Solution Approach 2:
The patent changes the optical length parameter by selectively removing conductive metal oxide layers in different pixel regions. This parameter adjustment is achieved through controlled etching or lifting-off processes that remove specific numbers of layers based on the required color, while maintaining consistent manufacturing conditions for all pixels. This approach ensures reliable quality control while achieving the desired full-color display performance.
3Illumination intensity
If a microresonator structure is implemented in organic EL display devices, then light emission brightness is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The conductive metal oxide layer serves multiple functions: it acts as the resonator spacer to define the microcavity optical length, provides electrical conductivity for the organic EL element operation, and enables wavelength selection through selective layer removal. This multi-functionality eliminates the need for separate components or processes, achieving the microresonator structure enhancement without proportionally increasing manufacturing complexity.
Solution Approach 2:
The patent merges the resonator spacer function with the conductive electrode function by using the conductive metal oxide layer for both purposes. Instead of requiring a separate non-conductive spacer layer and a separate conductive electrode layer, the conductive metal oxide layer performs both roles simultaneously. This merging simplifies the manufacturing process while maintaining the light emission brightness enhancement provided by the microresonator 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
This approach allows for the easy and accurate formation of optical microresonators in each pixel, improving light emission brightness and directionality while simplifying the manufacturing process, thereby enhancing display quality and reducing production costs.
Implementation Method 1
a microresonator (microcavity) structure... the optical length L between the semi-transmissive mirror and the metal electrode is designed such that the following equation (1) is satisfied: 2nL=(m+1/2)λ... it is possible to selectively intensify light at the wavelength λ
Implementation Method 2
a number of layers or a number of remaining layers of the transparent conductive metal oxide layers is changed among pixels having different light emission wavelengths so that a total thickness of the conductive resonator spacer layer for adjusting the optical length is changed
Data Source
AI summary
A display device having a plurality of pixels and which realizes a color display with emitted light of at least two wavelengths wherein each pixel has a microresonator structure between a lower reflective film formed on a side near a substrate and an upper reflective film formed above the lower reflective film with an organic light emitting element layer therebetween. The lower reflective film is made of a metal thin film and a conductive resonator spacer layer which functions as a first electrode is provided between the lower reflective film and the organic light emitting element layer. A thickness of the conductive resonator spacer layer is changed by changing a number of layers or a number of remaining layers of transparent conductive metal oxide layers made of ITO corresponding to pixels of different light emission wavelengths. An amorphous ITO layer at an upper layer is selectively removed from above a polycrystalline ITO layer at a lower layer using the polycrystalline ITO layer as an etching stopper so that the thickness is changed corresponding to the thickness of the ITO layer to be formed and not removed. Light obtained in the organic light emitting element layer is intensified by the microresonator structure in which the optical length is adjusted by the conductive resonator spacer layer and is emitted to the outside.