Core-Shell Fluorescent Material for LED Emission Intensity

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Solution Overview

Problem

Fluorescent materials used in light emitting devices often lack excellent emission intensity, which is crucial for effective light transmission and display quality.

Innovation Solution

A fluorescent material with a core-shell structure is developed, comprising a core part with a specific elemental composition and a shell part containing boron or silicon, optimized to enhance emission intensity through controlled tetrahedral site occupancy and specific surface area, thereby improving light emission efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If conventional fluorescent materials are used, then the device structure is simple, but the emission intensity is insufficient

Engineering Contradiction:
Improveemission intensityVSAvoidstructure complexity
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

The fluorescent material is divided into a core part and a shell part with distinct functions. The core part contains the发光 center (Mn, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Tm, or Yb) and provides light emission, while the shell part contains boron or silicon and protects the core. This segmentation allows optimization of emission intensity through controlled tetrahedral site occupancy in the core while maintaining structural stability through the shell, resolving the contradiction between improving emission intensity and maintaining structural simplicity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention uses a composite core-shell structure where the core part comprises a specific inorganic compound with controlled composition (MxMg1-xAlyOzNw) and the shell part contains boron or silicon. This composite structure combines the high emission intensity capability of the core with the protective and stabilizing properties of the shell, achieving excellent emission intensity while maintaining a relatively simple overall structure suitable for LED applications.

Inventive Principle:
Principle #40Composite materials

2Illumination intensity

If the tetrahedral site occupancy of M1 is increased to improve emission intensity, then the emission intensity improves, but the manufacturing precision requirements increase

Engineering Contradiction:
Improveemission intensityVSAvoidtetrahedral site occupancy control
Core Design Contradiction:
Illumination intensityVSManufacturing precision

Solution Approach 1:

The invention optimizes the tetrahedral site occupancy of M1 to a specific range (0.032 to 0.10) and controls the specific surface area (0.01 to 4.1 m2/g) to achieve excellent emission intensity. By defining precise parameter ranges rather than requiring exact values, the invention balances emission intensity improvement with manufacturability, allowing for reasonable variations in the firing process while maintaining performance.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The core part of the fluorescent material is designed with specific local properties including controlled tetrahedral site occupancy (0.032 to 0.10) and specific elemental composition (MxMg1-xAlyOzNw). This local optimization of the core region's quality ensures high emission intensity while the shell part provides structural support, allowing the critical parameters to be controlled within achievable manufacturing tolerances.

Inventive Principle:
Principle #3Local quality

3Use of energy by moving object

If the specific surface area is optimized to enhance emission intensity, then the light emission efficiency improves, but the manufacturing complexity increases

Engineering Contradiction:
Improvelight emission efficiencyVSAvoidmanufacturing complexity
Core Design Contradiction:
Use of energy by moving objectVSEase of manufacture

Solution Approach 1:

The invention specifies a controlled specific surface area range (0.01 to 4.1 m2/g) for the core part to optimize light emission efficiency. This parameter control, combined with the core-shell structure design, ensures that the fluorescent material achieves high emission intensity without requiring excessively complex manufacturing processes. The firing conditions (1250 to 1700°C) are set to achieve the desired surface area and crystal structure in a single step.

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 fluorescent material achieves excellent emission intensity, suitable for use in light emitting elements and devices, enhancing display quality and light transmission by optimizing the core-shell structure and elemental composition.

Implementation Method 1

Fluorescent material having excellent emission intensity

Methodology Applied
Scientific EffectPhotoluminescence: Photoluminescence

Data Source

PatentUS20230250332A1Fluorescent material
Publication Date: 2023.08.10 SUMITOMO CHEM CO LTD

AI summary

A fluorescent material has a core-shell structure. The core contains a crystal phase of an inorganic compound having Formula: MxMgaAlyOzNw (A); M represents a metal; x satisfies 0.001≤x≤0.3; a satisfies 0≤a≤1.0−x; y satisfies 1.2≤y≤11.3; z satisfies 2.8≤z≤18; and w satisfies 0≤w≤1.0. The shell is formed on at least a part of a surface of the core and contains boron and/or silicon. The core has a tetrahedral site occupancy of M1 of 0.032 or more and a specific surface area of 0.01 to 4.1 m2/g. A ratio Y/X of a peak area value Y of boron or silicon to a peak area value X of M present in the shell satisfies 0<Y/X≤0.095 when EDX measurement of a cross section of the fluorescent material is performed.