Manganese-Activated Silicofluoride Phosphor for Stable LED Emission

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Solution Overview

Problem

Conventional fluoride phosphors in light-emitting devices experience a decline in emission intensity over time, and surface treatment methods are costly and not suitable for high humidity conditions, while exposure to water further deteriorates their performance.

Innovation Solution

A manganese-activated potassium silicofluoride phosphor with a specific IR absorption spectrum and dehydration treatment at 400 to 800°C is used to maintain high emission intensity and internal quantum efficiency, reducing the presence of OH groups and defects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If conventional fluoride phosphors are continuously excited to emit luminescence, then the phosphor can produce light emission, but the emission intensity generally tends to go down from the initial intensity in course of time

Engineering Contradiction:

Improveemission intensityVSAvoidduration of light emission

Core Design Contradiction:

Illumination intensityVSDuration of action of stationary object

Solution Approach 1:

The patent changes the chemical composition parameters of the phosphor by incorporating specific metal elements (Mg, Zn, Cd, Hg, Mn, Fe, Co, Ni, Cu, Al, Ga, In, or their combinations) into the fluoride phosphor structure. This compositional modification fundamentally alters the phosphor's stability characteristics, enabling it to maintain high emission intensity over extended continuous operation periods without the intensity degradation observed in conventional fluoride phosphors.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the phosphors are surface-treated with a solution containing a surface-treatment agent to improve durability, then the emission intensity maintenance ratio is improved, but the production cost increases due to additional treatment steps

Engineering Contradiction:

Improvedurability under high temperature and high humidityVSAvoidproduction cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The phosphor achieves improved durability through its own inherent compositional structure rather than requiring external surface treatment. The specific metal element incorporation creates a self-stabilizing phosphor material that resists degradation under high temperature and humidity conditions without needing additional protective coatings or surface modifications, thereby eliminating extra production steps and costs.

Inventive Principle:

Principle #25Self-service

3Ease of manufacture

If conventional fluoride phosphors are brought into contact with water, then the phosphors can be processed or treated, but their emission intensity generally tends to deteriorate

Engineering Contradiction:

ImproveprocessabilityVSAvoidemission intensity

Core Design Contradiction:

Ease of manufactureVSIllumination intensity

Solution Approach 1:

The patent creates a composite phosphor structure by integrating multiple metal elements within the fluoride phosphor matrix. This composite composition provides both water resistance and processability, allowing the phosphor to undergo necessary manufacturing processes involving water while maintaining its emission intensity, unlike conventional fluoride phosphors that deteriorate upon water contact.

Inventive Principle:

Principle #40Composite materials

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 phosphor achieves a high emission intensity maintenance ratio and internal quantum efficiency, preventing color shift and intensity loss in light-emitting devices, even under continuous operation.

Implementation Method 1

A light-emitting diode (LED) light-emitting device mainly comprises a combination of a phosphor and a LED chip serving as an excitation light source

Methodology Applied

Scientific EffectPhotoluminescence: Photoluminescence

Implementation Method 2

dehydration treatment at 400 to 800°C is used to maintain high emission intensity and internal quantum efficiency, reducing the presence of OH groups and defects

Methodology Applied

Scientific EffectDehydration: Desiccation

Data Source

PatentUS9929321B2Phosphor, producing method thereof and light-emitting device employing the phosphor

Publication Date: 2018.03.27 NITERRA MATERIALS CO LTD

AI summary

The embodiment of the present disclosure provides a phosphor improved in the emission intensity maintenance ratio without impairing the emission intensity. The phosphor is a silicofluoride phosphor and shows an IR absorption spectrum satisfying the conditions of 0≤I2/I1≤0.01 and 6.7≤(I3/I1)/CMn. In those conditional formulas, I1, I2 and I3 are intensities of the maximum peaks in the ranges of 1200 to 1240 cm−1, 3570 to 3610 cm−1 and 635 to 655 cm−1, respectively, and CMn is a weight percent of Mn contained the phosphor.