Quantum Dot White Emission Layer for High Resolution Displays
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Solution Overview
Problem
Organic light emitting devices face challenges in achieving desirable aperture ratios for high-resolution displays and large-sized displays due to limitations in light emission structures, and the use of white organic emission layers with color filters can deteriorate light characteristics such as luminance and color reproducibility.
Innovation Solution
A display device is designed with a substrate, color filters, a common electrode, a white emission layer comprising quantum dots, and pixel switching elements, including insulating layers, gate electrodes, and source/drain electrodes, which allows for improved light characteristics and manufacturing simplicity by forming pixel switching elements after the white emission layer, enabling high resolution and large-sized displays with reduced voltage drop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a bottom emission structure is used, then the device can be manufactured, but it is difficult to obtain a desirable aperture ratio for high resolution
Solution Approach 1:
The patent inverts the traditional bottom emission structure to a top emission structure, where the substrate is transparent and light is emitted through the top surface. This inversion allows for higher aperture ratios in high-resolution displays while maintaining manufacturability through standard fabrication processes.
Solution Approach 2:
The patent introduces quantum dots with specific size ranges (2-10 nm) that emit blue light when excited, replacing traditional organic emission layers. This color change mechanism enables high-resolution color display with improved aperture ratios by using size-tuned quantum confinement effects.
2Area of stationary object
If a top emission structure with transparent electrode is used, then large-sized display can be achieved, but voltage drop occurs due to low conductivity
Solution Approach 1:
The patent employs a composite transparent electrode structure combining ITO (indium tin oxide) and MoO3 (molybdenum trioxide) layers. This composite material provides both high transparency for large-area displays and low electrical resistance to minimize voltage drop across the electrode surface.
Solution Approach 2:
The patent optimizes the thickness and composition parameters of the transparent electrode layers to achieve the desired balance between transparency and conductivity. By adjusting the ITO and MoO3 layer thicknesses and ratios, the electrode maintains low resistance for large displays while preserving optical transparency.
3Ease of manufacture
If white organic emission layer with color filters is used, then color image can be realized, but light characteristics such as luminance are deteriorated
Solution Approach 1:
The patent extracts and eliminates the color filter layer from the device structure, replacing it with quantum dots that directly emit blue light. This removal of the color filter eliminates the luminance loss associated with filtering, while quantum dots provide the necessary color conversion through photoluminescence, maintaining ease of manufacture.
Solution Approach 2:
The patent substitutes the mechanical/optical color filter system with a quantum dot photoluminescence system. Instead of using physical filters to select wavelengths, quantum dots convert blue light to red and green wavelengths through size-tuned photoluminescence, achieving color display with superior luminance efficiency.
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 characteristics like luminance and color reproducibility, simplifies the manufacturing process, and achieves a desirable aperture ratio for high-resolution and large-sized displays by using quantum dots in the white emission layer and inorganic layers for protection.
Implementation Method 1
the white emission layer comprises a plurality of quantum dots
Implementation Method 2
Electrons injected from one electrode and holes injected from the other electrode are combined in the organic emission layer to form excitons, and the excitons emit light as energy is discharged
Data Source
AI summary
A display device includes a substrate; a plurality of color filters on the substrate, a common electrode covering the plurality of color filters, a white emission layer covering the common electrode, a plurality of pixel electrodes on the white emission layer and a plurality of pixel switching elements on the plurality of pixel electrodes and connected to the plurality of pixel electrodes, wherein the white emission layer includes a plurality of quantum dots.