Quantum Dot Light-Emitting Element Patterning
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Solution Overview
Problem
Existing light-emitting elements using quantum dots face issues with residue from photolithography methods, material selection constraints, high driving voltage due to wettability changing layers, and uneven film thickness leading to suboptimal light-emission characteristics.
Innovation Solution
A light-emitting element with quantum dots where a surfactant is used to prevent agglomeration and control carrier recombination, allowing for thermal treatment to create light-emitting and non-light-emitting regions without photolithography, and a second electron transport layer enhances light emission with different wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If photolithography method is used to pattern light-emitting layer, then light-emitting regions can be formed, but photoresist residue remains on hole injection layer causing decreased light-emission characteristics
Solution Approach 1:
The patent extracts and removes the photoresist layer completely using oxygen plasma treatment before forming the light-emitting layer. This extraction principle eliminates the harmful residue that would otherwise degrade light-emission characteristics, while still achieving the desired patterned structure through selective area formation.
Solution Approach 2:
The patent segments the formation process into distinct stages: first forming the patterned hole injection layer, then selectively forming the light-emitting layer in specific regions. This segmentation allows precise control over where the light-emitting layer is formed without photoresist interference, maintaining both pattern integrity and emission quality.
2Shape
If photolithography method is used for patterning, then light-emitting regions can be defined, but material selection for hole injection layer is constrained by chemical resistance requirements
Solution Approach 1:
The patent replaces the chemical-based photolithography process with a physical plasma treatment process. This substitution eliminates the need for chemical resistance in the hole injection layer material, as oxygen plasma physically removes photoresist without requiring chemical interaction. Consequently, material selection is no longer constrained by chemical resistance requirements.
3Ease of manufacture
If wettability changing layer with photocatalyst is used, then light-emitting layer can be patterned without photolithography, but driving voltage becomes high due to additional layer
Solution Approach 1:
The patent extracts and eliminates the wettability changing layer from the device structure. Instead, it uses oxygen plasma treatment to directly pattern the hole injection layer and selectively form the light-emitting layer. This removal of the intermediate layer reduces the total number of layers, lowering the driving voltage while maintaining the patterning capability.
4Shape
If application liquid is applied onto wettability layer, then light-emitting layer forms in lyophilic region, but film thickness becomes uneven at boundaries causing suboptimal light-emission characteristics
Solution Approach 1:
The patent replaces the wettability-based liquid application method with a plasma-based physical treatment method. Oxygen plasma treatment creates well-defined patterns in the hole injection layer without relying on liquid wettability changes, thereby avoiding the boundary effects and film thickness non-uniformity that occur with liquid application methods.
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 simplifies patterning, reduces residue and material selection constraints, lowers driving voltage, and achieves uniform film thickness and high-efficiency light emission with varied wavelengths, enabling cost-effective and high-performance display devices.
Implementation Method 1
a surfactant is used to prevent agglomeration
Implementation Method 2
allowing for thermal treatment to create light-emitting and non-light-emitting regions
Implementation Method 3
Quantum dots which are ultrafine particles having a particle size of 10 nm or less are excellent in confinement of carriers (electrons, holes), so that excitons can be easily generated by recombination of electrons-holes
Data Source
AI summary
A light-emitting element where a positive electrode is formed on the surface of a transparent substrate; a hole transport layer is formed on the surface of the positive electrode; and a light-emitting layer made of quantum dots is formed on the surface of the hole transport layer. The light-emitting layer has a light-emitting region that emits light of a first predetermined wavelength in which a surfactant is present on the surface of the quantum dots and a non-light-emitting region that does not emit light in which a surfactant is absent on the surface of the quantum dots. A second light-emitting layer that emits light of a second predetermined wavelength is formed on the surface of the light-emitting layer, and a negative electrode is formed on the surface of the second light-emitting layer.