Bragg Reflector Cover Layer for Color Conversion Display Reliability
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Solution Overview
Problem
Current display devices face challenges in improving reliability, particularly in maintaining the effectiveness of color conversion layers due to potential deterioration from light emitting elements, which affects the overall luminance and efficiency of the pixels.
Innovation Solution
A display device design incorporating a cover layer with a distributed Bragg reflector structure between light emitting elements and color conversion layers, which includes sub-insulating layers with different refractive indices to enhance light output efficiency and maintain the reliability of the color conversion layer by maintaining a secure distance and preventing heat-induced deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a cover layer with distributed Bragg reflector structure is added between light emitting elements and color conversion layer, then light output efficiency is improved and luminance is increased, but device complexity increases due to additional multi-layer sub-insulating structures
Solution Approach 1:
The cover layer is segmented into multiple sub-insulating layers (first sub-insulating layer, second sub-insulating layer, third sub-insulating layer) with different refractive indices. Each layer serves a specific function in the distributed Bragg reflector structure, allowing optimization of light output efficiency through controlled reflection and transmission at each interface while maintaining modular fabrication processes.
Solution Approach 2:
The cover layer employs composite material structure combining multiple inorganic insulating materials with different refractive indices (such as silicon oxide, silicon nitride, and silicon oxynitride). This composite approach enables the distributed Bragg reflector to achieve high light output efficiency by exploiting refractive index contrasts between layers, while the materials are selected to be compatible with existing semiconductor fabrication processes.
2Volume of moving object
If the cover layer is positioned close to the color conversion layer to maintain compact structure, then device compactness is improved, but heat-induced deterioration of the color conversion layer occurs reducing reliability
Solution Approach 1:
The cover layer acts as an intermediary structure between the light emitting elements and the color conversion layer. It provides thermal isolation while maintaining optical functionality, allowing the device to remain compact without subjecting the color conversion layer to excessive heat from the light emitting elements, thus preventing heat-induced deterioration.
Solution Approach 2:
The cover layer is designed with spatially varying properties - it is positioned closer to light emitting elements in regions where thermal management is critical, while maintaining appropriate distances from the color conversion layer. The multi-layer structure with different refractive indices creates local optical and thermal characteristics that protect the color conversion layer while preserving device compactness.
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 effectively improves the luminance of pixels by increasing light output efficiency and enhances the reliability of the display device by protecting the color conversion layer from deterioration, thereby maintaining consistent performance.
Implementation Method 1
a cover layer having a distributed Bragg reflector structure may be disposed between a light emitting element and a color conversion layer (or QD layer) to reflect light proceeding toward a rear surface of the color conversion layer to a front surface direction
Implementation Method 2
The first layer and the second layer may have different refractive indices
Implementation Method 3
the color conversion layer may include color conversion particles that convert light emitted from the plurality of light emitting elements into light having a different wavelength range
Data Source
AI summary
A display device according to an embodiment includes a substrate including an emission area and a non-emission area, a plurality of light emitting elements disposed on the substrate, a first electrode and a second electrode disposed to be spaced apart from each other and electrically connected to plurality of the light emitting elements, a cover layer disposed on the first electrode and the second electrode, and a color conversion layer disposed on the cover layer. The cover layer includes a plurality of sub-insulating layers each including a first layer and a second layer sequentially stacked. The first layer and the second layer have different refractive indices.