Ce-Activated Ca2Si3N8 Red Phosphor for High-Brightness White LEDs

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Solution Overview

Problem

Existing light emitting devices using Eu-activated nitride-based red phosphors experience brightness saturation under high-power excitation, limiting their ability to produce high-brightness, warm-colored white light with high color rendering properties.

Innovation Solution

A red phosphor with the chemical formula CazO:Cex,Liy, where 0<x<0.2, 0≤y<0.2, and 1−x−y≤z≤1−x, is used, featuring a CaO crystal structure and Ce as the light emission center, which maintains high light emission brightness even under high-power excitation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If Eu-activated nitride-based red phosphor is used to achieve high color rendering, then color rendering index (Ra and R9) is improved, but light emission brightness decreases under high-power excitation

Engineering Contradiction:

Improvecolor rendering indexVSAvoidlight emission brightness

Core Design Contradiction:

Measurement precisionVSIllumination intensity

Solution Approach 1:

The patent changes the chemical composition parameters of the red phosphor by substituting Eu3+ ions with Ce3+ ions and adjusting the host matrix composition (CaAlSiN3 to Ca2Si3N8). This parameter change transforms the phosphor's excitation characteristics to match blue LED excitation sources while maintaining red emission, thereby resolving the contradiction between color rendering and brightness under high-power excitation

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite phosphor system combining Ca2Si3N8 host matrix with Ce3+ activator ions, replacing the traditional Eu-activated nitride-based phosphor. This composite material achieves both high color rendering (R9>90) and high brightness under blue LED excitation, simultaneously satisfying both requirements that were previously contradictory

Inventive Principle:

Principle #40Composite materials

2Illumination intensity

If high-power excitation source is used to increase brightness, then illumination intensity is improved, but light emission brightness saturation occurs with Eu-activated phosphor

Engineering Contradiction:

ImprovebrightnessVSAvoidbrightness saturation resistance

Core Design Contradiction:

Illumination intensityVSReliability

Solution Approach 1:

The patent changes the activator ion parameter from Eu3+ to Ce3+, which fundamentally alters the excitation mechanism. Ce3+ ions have excitation bands that overlap with blue LED emission, enabling efficient energy transfer and maintaining high brightness without saturation even under high-power excitation conditions

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent substitutes the traditional Eu-activated phosphor mechanism with a Ce-activated phosphor mechanism that is specifically optimized for blue LED excitation. This substitution replaces a system that saturates under high power with one that maintains linear brightness response, improving reliability under high-power operation

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Device complexity

If Ce-activated YAG-based yellow phosphor is used to simplify device structure, then device complexity is reduced, but color rendering quality deteriorates

Engineering Contradiction:

Improvephosphor combination structureVSAvoidcolor rendering index

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent changes the phosphor composition parameters from YAG:Ce yellow phosphor to Ca2Si3N8:Ce red phosphor. This parameter change shifts the emission wavelength to the red region, enabling warm white light with high color rendering index (R9>90) while maintaining the simplicity of using a single phosphor with blue LED

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent develops a composite red phosphor material Ca2Si3N8:Ce that combines the advantages of simple device structure (single phosphor system) with high color rendering performance (R9>90). This composite material replaces the two-phosphor YAG:Ce system, achieving both simplicity and quality

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 red phosphor achieves high color rendering and brightness with minimal light emission brightness decrease under high-power sources, enabling the creation of high-brightness, high-color-rendering light emitting devices.

Implementation Method 1

a red phosphor that absorbs blue-based excitation light and emits red fluorescence

Methodology Applied

Scientific EffectFluorescence: Fluorescence

Data Source

PatentUS10982142B1Red phosphor and light emitting device using the same

Publication Date: 2021.04.20 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

A red phosphor is expressed by a chemical formula of CazO:Cex, Liy, in which a range of x values is 0<x<0.2, a range of y values is 0≤y<0.2, and a range of z values is 1−x−y≤z≤1−x.