Moisture-Resistant Phosphor Coating for Lighting Stability

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Solution Overview

Problem

Red-emitting phosphors based on Mn4+ doped fluoride materials are susceptible to degradation under use conditions, limiting their stability and performance in lighting systems.

Innovation Solution

A moisture-resistant phosphor composition is developed by coating K2SiF6:Mn4+ particles with a manganese-free complex fluoride of formula A3[MF6], where A is selected from Na, K, Rb, and M is selected from Al, Ga, In, Sc, Y, Gd, and combinations thereof, resulting in a phosphor composition with lower water solubility and enhanced stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If Mn4+ doped fluoride phosphors are used to achieve high efficacy and CRI in lighting systems, then the lighting performance is improved, but the phosphor becomes susceptible to moisture-induced degradation

Engineering Contradiction:

Improvelighting efficacyVSAvoidmoisture resistance

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

A moisture-resistant coating layer is applied as an intermediary between the Mn4+ doped fluoride phosphor particles and the humid environment. This coating acts as a protective barrier that prevents direct contact between moisture and the phosphor, thereby maintaining both the high lighting efficacy and improving moisture resistance simultaneously

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If post-synthesis processing steps are applied to reduce degradation, then the stability is improved, but the manufacturing complexity increases

Engineering Contradiction:

Improvephosphor stabilityVSAvoidprocessing steps

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The moisture-resistant coating is applied as a preliminary protective layer during or immediately after the phosphor synthesis process. By pre-establishing this protective barrier before the phosphor is deployed in lighting systems, the need for complex post-synthesis processing steps is reduced, thereby improving stability while minimizing manufacturing complexity

Inventive Principle:

Principle #10Preliminary action

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 coated phosphor composition exhibits high resistance to moisture-induced degradation, maintaining intense red luminescence and stability under high temperature and humidity conditions, thereby improving the performance and longevity of lighting systems.

Implementation Method 1

The composition of formula I: A3[MF6] has lower water solubility than a water solubility of K2SiF6

Methodology Applied

Scientific EffectSolubility reduction:

Implementation Method 2

These materials absorb blue light strongly and efficiently emit between about 610-635 nm

Methodology Applied

Scientific EffectLuminescence: Luminescence

Implementation Method 3

maintaining intense red luminescence and stability under high temperature and humidity conditions

Methodology Applied

Scientific EffectThermal stability:

Data Source

PatentUS10131835B2Moisture-resistant phosphor compositions and associate methods

Publication Date: 2018.11.20 GE LIGHTING SOLUTIONS LLC

AI summary

A phosphor composition is derived from combining K2SiF6:Mn4+ in solid form with a saturated solution of a manganese-free complex fluoride including a composition of formula I: A3[MF6], where A is selected from Na, K, Rb, and combinations thereof and M is selected from Al, Ga, In, Sc, Y, Gd, and combinations thereof. The composition of formula I: A3[MF6] has a water solubility lower than a water solubility of K2SiF6. A lighting apparatus including the phosphor composition is also provided.