Garnet-Coated Phosphor Ceramic Composite for Thermal Management

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Solution Overview

Problem

Existing solid-state light emitting devices with phosphors are prone to degradation due to temperature and humidity changes, leading to shortened lifespans, as they face challenges in heat dissipation and fluorescence characteristic deterioration.

Innovation Solution

A ceramic composite with phosphor particles coated by a garnet-structured layer having a thickness between 0.001 μm and 0.450 μm, which enhances thermal conductivity and stability against environmental changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a phosphor is used in solid-state light emitting devices, then light emission function is achieved, but the phosphor deteriorates due to light exposure, temperature changes, and humidity, shortening device lifespan

Engineering Contradiction:

Improvedevice lifespanVSAvoidphosphor deterioration

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A silica coating layer is applied as an intermediary protective barrier between the phosphor particle and the external environment. This coating layer shields the phosphor from harmful factors including light exposure, humidity, and temperature fluctuations, thereby preventing deterioration and extending device lifespan while maintaining the phosphor's light emission functionality.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention creates a composite structure consisting of a phosphor particle core and a silica coating shell. This composite design combines the light-emitting properties of the phosphor with the protective characteristics of silica, forming a core-shell type composite phosphor that simultaneously achieves functional performance and environmental resistance.

Inventive Principle:

Principle #40Composite materials

2Reliability

If the coating layer thickness is increased to improve protection, then phosphor durability improves, but light emission efficiency may deteriorate

Engineering Contradiction:

Improvephosphor durabilityVSAvoidlight emission efficiency

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The invention optimizes the coating layer thickness within a specific range (0.01 μm to 0.5 μm) to achieve the best balance between protection and light emission efficiency. By precisely controlling this parameter, the coating provides sufficient environmental protection while remaining thin enough to allow effective light transmission and maintain high phosphor efficiency.

Inventive Principle:

Principle #35Parameter changes

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 ceramic composite effectively suppresses temperature quenching and maintains fluorescence efficiency, ensuring longer device lifespan and improved reliability under varying environmental conditions.

Implementation Method 1

the coating layer has identical garnet structures as the phosphor particle, thereby the ceramic composite is capable of suppressing temperature quenching

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS11401464B2Ceramic composite

Publication Date: 2022.08.02 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

A ceramic composite having a phosphor particle and a coating layer on the surface of the phosphor particle, in which a matrix crystal structure of the phosphor particle and the coating layer have identical garnet structures, and the thickness of the coating layer is greater than or equal to 0.001 μm and smaller than or equal to 0.450 μm.