Quantum Dot LED Protective Layer for Moisture and Oxygen Blocking
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Solution Overview
Problem
Quantum dot light emitting devices have insufficient water and oxygen barrier properties due to the accelerated movement of molecular chains caused by differing expansion coefficients between quantum dots and polymers, leading to increased water and oxygen intrusion.
Innovation Solution
A light emitting device is designed with a substrate, an LED chip, a quantum dot composite layer, and multiple protective layers, including a water-soluble polymer matrix and inorganic oxide or water-blocking polymers, which effectively encapsulate the quantum dot composite layer and form a robust water-oxygen barrier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If quantum dots are added to UV or thermal curable polymers and cured to form QDs-matrix structure, then the quantum dot light emitting device can be manufactured, but the differing expansion coefficients between quantum dots and polymers cause accelerated molecular chain movement creating channels for water and oxygen intrusion
Solution Approach 1:
The patent uses a composite protective layer comprising inorganic oxide particles (such as silicon dioxide or aluminum oxide) dispersed in a polymer matrix. This composite structure combines the barrier properties of inorganic materials with the adhesion and flexibility of organic polymers, effectively blocking water and oxygen penetration while accommodating the expansion coefficient differences between quantum dots and polymers.
Solution Approach 2:
The protective layer is designed with local differentiation where inorganic oxide particles are distributed throughout the polymer matrix to create localized barrier regions. This allows different parts of the protective layer to perform specialized functions: inorganic particles provide water and oxygen blocking at critical points, while the polymer matrix provides continuous coverage and stress distribution.
2Ease of manufacture
If quantum dots are added to PMMA or other polymer solutions and solidified by volatilizing solvents to form QDs-PMMA dispersions, then the quantum dot light emitting device can be manufactured, but the accelerated movement of molecular chains creates small changeable and instantaneous channels through which water vapor and oxygen can pass
Solution Approach 1:
The protective layer combines inorganic oxide particles with polymer matrix to form a composite barrier. The inorganic particles create tortuous paths that block water and oxygen molecules, while the polymer provides a continuous phase that seals around the particles, preventing direct penetration through the structure.
Solution Approach 2:
The polymer matrix acts as an intermediary between the quantum dots and the external environment. It provides a flexible matrix that can accommodate volume changes while the inorganic oxide particles embedded within it serve as intermediate barrier elements that actively block water and oxygen transport pathways.
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 significantly improves the stability and reduces surface defects of the quantum dot composite layer, enhancing the water and oxygen barrier properties of the light emitting device, maintaining high quantum yield and luminance even under aging conditions.
Implementation Method 1
the material of the first protective layer is one of a first inorganic oxide and a first water-blocking polymer
Implementation Method 2
the material of the water-soluble polymer matrix is an oxygen-blocking polymer
Implementation Method 3
the first protective layer is formed by providing one or more solutions of an organic silicate, an organic aluminum silicate and a silazane on the surface of the quantum dot composite layer, and hydrolyzing for solidification
Data Source
AI summary
The disclosure provides a light emitting device and a manufacturing method thereof. The light emitting device includes a substrate, an LED chip, a quantum dot composite layer and a first protective layer; the LED chip is disposed on a surface of the substrate; the quantum dot composite layer is arranged on a surface of the LED chip away from the substrate; the first protective layer is arranged on a surface of the quantum dot composite layer away from the LED chip; wherein the quantum dot composite layer includes a water-soluble polymer matrix and quantum dots dispersed in the water-soluble polymer matrix; the material of the first protective layer is one of a first inorganic oxide and a first water-blocking polymer; and the material of the water-soluble polymer matrix is an oxygen-blocking polymer.