Light Emitting Device Resin Composition Nanoparticle Encapsulation
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Solution Overview
Problem
Conventional Mn4+-activated red-light fluoride fluorescent materials in light emitting devices suffer from chromaticity changes and emission output losses due to manganese dioxide formation on the particle surface when exposed to water, making them unsuitable for reliable use in liquid crystal backlights.
Innovation Solution
A light emitting device with a resin composition containing a red-light emitting fluoride material having a chemical composition with tetravalent manganese, alkali metal elements, and elements from Group 4 and Group 14, along with nanoparticles like silicon oxide, which reduces the Mn4+ concentration on the surface and prevents water reaction, enhancing durability and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional Mn4+-activated red-light fluoride fluorescent materials are used, then the light emitting device can achieve red light emission, but the fluorescent material suffers from chromaticity changes and emission output losses due to manganese dioxide formation on the particle surface when exposed to water
Solution Approach 1:
The patent introduces an encapsulation member as an intermediary barrier between the fluorescent material and water. This encapsulation layer prevents direct contact between water and the Mn4+-activated fluoride fluorescent material particles, thereby preventing manganese dioxide formation on the particle surface while still allowing the device to achieve red light emission. The encapsulation member acts as a protective mediator that isolates the harmful interaction between water and the fluorescent material.
Solution Approach 2:
The patent employs composite material structure by combining the fluorescent material with an encapsulation member forming a protected composite system. This composite structure integrates the light-emitting functionality of the Mn4+-activated fluoride material with the protective properties of the encapsulation layer, achieving both red light emission and resistance to chromaticity changes and emission output losses.
2Device complexity
If the fluorescent material is exposed to water, then the device structure remains simple, but the manganese dioxide formation on the particle surface causes chromaticity changes and emission output losses
Solution Approach 1:
The encapsulation member serves as a simple intermediary layer that adds minimal structural complexity while providing effective protection. This single-layer encapsulation approach maintains device simplicity while preventing water exposure to the fluorescent material, thereby ensuring stability without requiring complex multi-layer structures or additional protective components.
3Illumination intensity
If the Mn4+ concentration on the surface is high, then the red light emission intensity is high, but the reaction with water is accelerated causing faster chromaticity changes and emission output losses
Solution Approach 1:
The encapsulation member acts as a protective intermediary that allows the fluorescent material to maintain high Mn4+ concentration on the particle surface for strong red light emission intensity, while simultaneously preventing water from reaching the high-Mn4+ surface regions. This mediator approach enables the device to achieve both high illumination intensity and resistance to chromaticity changes by blocking the harmful water-Mn4+ interaction.
Solution Approach 2:
The patent applies local quality differentiation by having different properties in different regions: the interior particle surface maintains high Mn4+ concentration for optimal light emission, while the exterior encapsulation layer provides water resistance. This spatial differentiation of properties allows the system to simultaneously achieve high emission intensity and stability by protecting the high-Mn4+ regions from water exposure.
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 reduces chromaticity changes and emission output losses, providing superior durability and reliability for light emitting devices, especially in humid environments.
Implementation Method 1
a light emitting element that emits ultraviolet light and three types of fluorescent materials that emit red (R), green (G), and blue (B) light... systems using a light emitting element that emits a blue light and a fluorescent material that emits, e.g., a yellow light
Implementation Method 2
an encapsulation member that covers the light emitting element and that is a cured product of a resin composition containing a fluorescent material, a resin, and nanoparticles... the content of the silicon oxide nanoparticles is 0.02 to 5 mass parts relative to 100 mass parts of the resin
Data Source
AI summary
Provided a light emitting device comprising: a package; a light emitting element disposed in the package; an encapsulation member that covers the light emitting element, the encapsulation member being formed from a resin composition that contains a fluorescent material, a resin, and nanoparticles selected from at least one of the group consisting of aluminum oxide nanoparticles, titanium oxide nanoparticles, zinc oxide nanoparticles, zirconium oxide nanoparticles, and silicon oxide nanoparticles, wherein when the resin composition includes silicon oxide nanoparticles, the content of the silicon oxide nanoparticles is 0.02 to 5 mass parts relative to 100 mass parts of the resin; and wherein the fluorescent material is a red-light emitting fluorescent material including a fluoride material having a chemical composition that includes tetravalent manganese, at least one selected from the group consisting of alkali metal elements and NH4+, and at least one selected from the group consisting of elements from Group 4 of the periodic table and elements from Group 14 of the periodic table.