Mn4+ Phosphor Surface Modification for Moisture Resistance
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Solution Overview
Problem
Mn4+-activated complex fluoride phosphors used in LED light emitting devices have low stability due to hydrolysis when exposed to water or water vapor, leading to reduced fluorescence properties and potential corrosion of peripheral materials.
Innovation Solution
Surface modification of Mn4+-activated complex fluoride phosphors with calcium (Ca) or chlorine (Cl) in specific concentration ranges improves moisture resistance without compromising fluorescence properties, using compounds as Ca or Cl sources to deposit or substitute F on the phosphor particle surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If Mn4+-activated complex fluoride phosphors are used to achieve narrow half value width and high luminance, then color rendering properties are improved, but moisture resistance deteriorates due to hydrolysis
Solution Approach 1:
The patent applies local quality by modifying only the surface layer of the phosphor particles with calcium or chlorine, while keeping the core Mn4+-activated complex fluoride structure intact. This surface modification creates a protective barrier against moisture without altering the bulk optical properties, thus maintaining narrow half value width and high luminance while improving moisture resistance
Solution Approach 2:
The patent creates a composite structure by combining Mn4+-activated complex fluoride phosphor with calcium or chlorine surface modification. This composite approach integrates the high-performance optical properties of the original phosphor with the moisture-resistant characteristics of the calcium/chlorine surface layer, resolving the contradiction between luminance performance and moisture stability
2Reliability
If surface modification with Ca or Cl is applied to improve moisture resistance, then durability is improved, but fluorescence properties may be compromised
Solution Approach 1:
The patent applies parameter changes by precisely controlling the concentration ranges of calcium (20-10,000 ppm) or chlorine (20-300 ppm) in the surface modification. By optimizing these concentration parameters, the invention achieves sufficient moisture resistance while minimizing the impact on fluorescence properties, thus resolving the contradiction between durability and optical performance
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 modified phosphors exhibit superior moisture resistance, maintaining high color rendering properties and luminance with minimal change over time, enhancing the durability and reliability of LED light emitting devices.
Implementation Method 1
phosphors using Eu3+ and Mn4+ as the light emission central ions have been developed as red phosphors having light emission spectra with narrow half value width
Implementation Method 2
treating Mn4+-activated complex fluoride phosphors, which have excellent luminance, with a compound to serve as a Ca or Cl source and modifying the particle surfaces
Implementation Method 3
hydrolysis of the phosphor tends to progress upon contact with water or water vapor... by treating Mn4+-activated complex fluoride phosphors with a compound to serve as a Ca or Cl source and modifying the particle surfaces
Data Source
AI summary
The present invention relates to an Mn4+-activated complex fluoride phosphor with improved moisture resistance due to modification of the particle surface, and a light emitting element and light emitting device having excellent color rendering properties and stability due to the use of this phosphor.The phosphor of the present invention is characterized in that it is represented by the general formula: A2MF6:Mn4+, wherein element A is an alkali metal element comprising at least K, element M is one or more metal elements chosen from among Si, Ge, Sn, Ti, Zr and Hf, F is fluorine, and Mn is manganese, wherein the phosphor comprises Ca in a concentration range of at least 20 ppm and at most 10,000 ppm or Cl in a concentration range of at least 20 ppm and at most 300 ppm.