Quantum-Dot Layer Roughness for Display Light Extraction
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Solution Overview
Problem
Display apparatuses have a complicated structure, resulting in low light efficiency.
Innovation Solution
A display apparatus with a simple structure is achieved by incorporating a light-emitting element, an encapsulation layer, a bank with an opening for the light-emitting element, and a quantum-dot layer, where the roughness of the upper surface of the quantum-dot layer and the bank is greater than the lower surface, and a protective layer and color filter layer are added, with the height of the bank reduced using a chemical mechanical polishing process to enhance light efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a complicated structure is used in display apparatus, then manufacturing flexibility is improved, but light efficiency deteriorates
Solution Approach 1:
The patent extracts and removes the bank structure from the display apparatus, keeping only the essential components (light-emitting element, encapsulation layer, quantum-dot layer, protective layer, and color filter layer). This extraction eliminates the light-blocking bank structure while maintaining manufacturing flexibility through the simplified layer sequence.
Solution Approach 2:
The patent segments the display apparatus into distinct functional layers: light-emitting element, encapsulation layer, quantum-dot layer, protective layer, and color filter layer. Each layer performs a specific function, allowing independent optimization of light efficiency without compromising manufacturing flexibility.
2Strength
If bank structure is used to hold quantum-dot layer, then structural support is improved, but light extraction efficiency deteriorates
Solution Approach 1:
The bank structure is completely removed from the display apparatus. The quantum-dot layer is directly formed on the encapsulation layer without requiring a bank structure for support, thereby eliminating light blockage and improving light extraction efficiency while maintaining adequate structural support through the layer configuration.
3Manufacturing precision
If smooth surfaces are used for quantum-dot layer and bank, then manufacturing precision is improved, but light efficiency deteriorates
Solution Approach 1:
The patent applies different surface qualities to different regions: the lower surface of the quantum-dot layer (contacting encapsulation layer) has low roughness for good adhesion and manufacturing precision, while the upper surface has high roughness (1 nm to 500 nm) to scatter light and improve extraction efficiency. This local differentiation resolves the contradiction between manufacturing precision and light efficiency.
Solution Approach 2:
The patent changes the surface roughness parameter of the quantum-dot layer from uniform to non-uniform, with the upper surface having controlled roughness (1 nm to 500 nm) to enhance light scattering and extraction efficiency, while the lower surface maintains smoothness for manufacturing precision and adhesion.
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 results in a display apparatus with high light efficiency and a simplified structure, improving light extraction and maintaining image quality by optimizing the surface roughness and layer thickness.
Implementation Method 1
light of a first color generated by an emission part of some pixels is converted to light of a second color while passing through the color converter and emitted to the outside
Implementation Method 2
The reducing of the height of the bank may include using a chemical mechanical polishing process
Data Source
AI summary
A display apparatus includes a light-emitting element, an encapsulation layer covering the light-emitting element, a bank on the encapsulation layer and including an opening corresponding to the light-emitting element, and a quantum-dot layer in the opening of the bank. Roughness of a lower surface of the quantum-dot layer which is closest to the encapsulation layer is different from roughness of an upper surface of the quantum-dot layer which is furthest from the encapsulation layer.