Hybrid Phosphor Particle Coating for Moisture and Mechanical Stability
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Solution Overview
Problem
Existing luminescent materials face issues such as decomposition due to moisture, mechanical instability, and decreased quantum efficiency when coated with traditional methods, which result in agglomeration and non-conformal coatings, limiting their durability and performance, especially in high-stress applications like high-power LED systems.
Innovation Solution
A hybrid coating method involving a primer layer, followed by an atomic layer deposition (ALD) coating, and a sol-gel coating is applied to luminescent particles, providing a moisture barrier and mechanical protection while maintaining quantum efficiency, using a combination of metal oxide precursors like Al, Zn, Hf, Ta, Zr, Ti, Sn, Nb, Y, Ga, and V to create a multilayer structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a sol-gel coating is applied to luminescent particles, then mechanical protection is provided, but the coating may not provide sufficient moisture barrier properties
Solution Approach 1:
The patent applies a hybrid coating combining sol-gel and ALD materials to create a composite coating structure. The sol-gel layer provides mechanical strength and protection, while the ALD layer provides superior moisture barrier properties. This composite approach resolves the contradiction by combining the advantages of both materials rather than relying on a single coating type.
Solution Approach 2:
The patent uses a multi-layer coating structure where one coating is applied over another. The sol-gel coating is applied first to provide mechanical protection, followed by an ALD coating applied over it to provide the moisture barrier. This nested structure allows each layer to perform its specialized function without interfering with the other.
2Reliability
If an ALD coating is applied to luminescent particles, then moisture barrier properties are improved, but mechanical stability during processing deteriorates
Solution Approach 1:
The patent applies the ALD coating over the sol-gel coating rather than directly on the luminescent particle. The sol-gel layer acts as a mechanical support structure that provides stability during processing, while the thinner ALD layer maintains its moisture barrier function. This nested arrangement allows the ALD coating to be mechanically supported without compromising its barrier properties.
Solution Approach 2:
The hybrid composite coating combines the mechanical robustness of sol-gel with the moisture barrier excellence of ALD materials. The composite structure allows the ALD layer to achieve superior moisture protection while the sol-gel layer compensates for the inherent mechanical fragility of thin ALD coatings.
3Ease of manufacture
If traditional coating methods are used, then application is simple, but decomposition due to moisture and reduced quantum efficiency occur
Solution Approach 1:
The patent divides the coating process into two separate sequential steps: first applying sol-gel coating, then applying ALD coating. This segmentation allows each coating method to be optimized for its specific function while maintaining relative simplicity in each individual step. The modular approach avoids the complexity of trying to achieve both mechanical strength and moisture barrier in a single coating process.
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 hybrid coating significantly reduces decomposition rates and enhances chemical and mechanical stability, allowing luminescent particles to perform effectively in high-stress conditions with quantum efficiencies comparable to uncoated materials, while providing superior moisture resistance and stability.
Implementation Method 1
The coating may be applied by depositing a material at the particle surfaces by reacting a dissolved inorganic precursor in a suspension (e.g. by a sol-gel process) or by deposition from the gas phase (e.g. a chemical vapor deposition or an atomic layer deposition (ALD) process).
Implementation Method 2
The coating may be applied by depositing a material at the particle surfaces by reacting a dissolved inorganic precursor in a suspension (e.g. by a sol-gel process)
Data Source
AI summary
The invention provides a method for providing a luminescent particle (100) with a hybrid coating, the method comprising: (i) providing a luminescent core (102) comprising a primer layer (105) on the luminescent core (102); (ii) providing a main ALD coating layer (120) onto the primer layer (105) by application of a main atomic layer deposition process, the main ALD coating layer (120) comprising a multilayer (1120) with two or more layers (1121) having different chemical compositions, and wherein in the main atomic layer deposition process a metal oxide precursor is selected from a group of metal oxide precursors comprising Al, Zn, Hf, Ta, Zr, Ti, Sn, Nb, Y, Ga, and V; (iii) providing a main sol-gel coating layer (130) onto the main ALD-coating layer (120) by application of a main sol-gel coating process, the main sol-gel coating layer (130) having a chemical composition different from one or more of the layers (1121) of the multilayer (1120).