White OLED with Single Emissive Layer and Color Conversion
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Solution Overview
Problem
Conventional organic electroluminescent displays face issues such as color shift, reduced process yield, and difficulty in producing pure white light, particularly due to the use of multiple emissive layers and the need for complex color conversion media.
Innovation Solution
A white organic electroluminescent device with a single emissive layer and an organic color conversion layer that serves as both a carrier injecting and transporting layer, allowing for the generation of white light through photoluminescence without the need for multiple color conversion layers, thereby simplifying the manufacturing process and reducing color impurity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple emissive layers are used to generate different color lights, then color display capability is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The device segments the color generation function into two independent parts: a single emissive layer that generates white light containing all wavelengths, and separate color filter layers for each sub-pixel that select specific color wavelengths. This segmentation allows color display without the complexity of multiple emissive layers, as each color is filtered independently rather than generated by complex multi-layer structures.
Solution Approach 2:
The single emissive layer serves a universal function by generating white light that contains all visible wavelengths simultaneously. This multi-functional light source replaces the need for multiple specialized emissive layers (red, green, blue), simplifying the device structure while maintaining full-color display capability through the universal white light generation.
2Adaptability or versatility
If multiple emissive layers are used to generate different color lights, then color display capability is improved, but process yield decreases
Solution Approach 1:
The manufacturing process is segmented into independent stages: first forming a single emissive layer that requires only one photomask pattern, then separately forming color filter layers. This segmentation eliminates the need for complex multi-layer alignment processes, reducing manufacturing steps and improving process yield while maintaining color display functionality.
Solution Approach 2:
The white light emissive layer is formed first as a preliminary structure before adding color filters. This preliminary action establishes a simple base layer that requires minimal alignment, and subsequent color filter layers are added independently, avoiding the complex sequential alignment required for multiple emissive layers and thereby improving process yield.
3Device complexity
If color filters are used to generate red, green, and blue lights from white light, then device complexity is reduced, but light intensity decreases
Solution Approach 1:
The color filter layers are designed with local quality optimization by using high-transmittance materials and optimized thickness for each color channel. The filters are engineered to transmit maximum light intensity for their respective colors (red, green, blue) while maintaining color purity, thereby reducing light intensity loss despite the use of multiple filtering stages.
4Productivity
If CCM is used to convert blue light into other color lights, then process yield increases, but color purity decreases
Solution Approach 1:
Instead of using CCM for color conversion, the invention segments color generation into independent color filter layers for red, green, and blue sub-pixels. Each filter layer independently selects its color from the white light spectrum, avoiding the color mixing and purity degradation issues of CCM while maintaining simplified manufacturing 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
This approach avoids color shift by ensuring well-distributed excitons and simplifies production by eliminating the need for multiple emissive layers and their isolating structures, while enhancing light intensity and purity through the use of a single wavelength light generation.
Implementation Method 1
an organic color conversion layer capable of acting as a carrier injecting layer due to photoluminescent property
Implementation Method 2
When a hole combines with an electron to generate an exciton in different emissive layers, the different color lights are generated
Data Source
AI summary
An organic electroluminescent device comprises a first electrode, an organic color conversion layer, a carrier transport layer, an emissive layer, and a second electrode. The organic color conversion layer is disposed over the first electrode. The carrier transport layer is disposed over the organic color conversion layer. The emissive layer is disposed over the carrier transport layer. The second electrode is disposed over the emissive layer.