Phosphor Particle Dispersion for Micro LED Light Conversion

Solution Overview

Problem

The miniaturization of micro LEDs faces challenges with phosphor particle aggregation, leading to increased transmittance of excitation light and nozzle clogging during the formation of the light conversion layer, which affects performance.

Innovation Solution

The use of ultrasonic homogenizer treatment to control the particle size distribution of phosphor particles, specifically by adjusting the cumulative 50% and 90% particle sizes, and dispersing them in a sodium hexametaphosphate solution, effectively preventing aggregation while maintaining performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If the particle size of phosphor particles is reduced, then the performance of micro LED is improved, but the phosphor particles are more easily aggregated causing increased transmittance of excitation light and nozzle clogging

Engineering Contradiction:

Improveparticle sizeVSAvoidaggregation suppression

Core Design Contradiction:

Length of moving objectVSReliability

Solution Approach 1:

The patent applies preliminary action by performing ultrasonic homogenizer treatment on the phosphor particles before they are used in the micro LED device. This treatment is conducted in advance to control the particle size distribution and prevent aggregation during subsequent processing and operation. The ultrasonic treatment modifies the particle characteristics beforehand, ensuring they maintain proper dispersion when applied to the micro LED structure.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent utilizes mechanical vibration through ultrasonic homogenizer treatment to disperse and size-control the phosphor particles. The ultrasonic waves create mechanical vibration that prevents particle aggregation and achieves the desired particle size distribution. This vibration-based approach effectively addresses the aggregation problem that occurs when particle size is reduced for micro LED applications.

Inventive Principle:

Principle #18Mechanical vibration

2Length of moving object

If the particle size of phosphor particles is reduced, then the performance of micro LED is improved, but nozzle clogging occurs during formation of the light conversion layer

Engineering Contradiction:

Improveparticle sizeVSAvoidnozzle clogging

Core Design Contradiction:

Length of moving objectVSEase of manufacture

Solution Approach 1:

The patent applies preliminary action by performing ultrasonic homogenizer treatment on the phosphor particles before they are used in the micro LED device. This treatment is conducted in advance to control the particle size distribution and prevent aggregation during subsequent processing and operation. The ultrasonic treatment modifies the particle characteristics beforehand, ensuring they maintain proper dispersion when applied to the micro LED structure.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent utilizes mechanical vibration through ultrasonic homogenizer treatment to disperse and size-control the phosphor particles. The ultrasonic waves create mechanical vibration that prevents particle aggregation and achieves the desired particle size distribution. This vibration-based approach effectively addresses the aggregation problem that occurs when particle size is reduced for micro LED applications.

Inventive Principle:

Principle #18Mechanical vibration

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

This approach suppresses particle aggregation and maintains performance even at reduced sizes, enhancing light emission characteristics and reducing the risk of clogging, thereby improving the efficiency of micro LED displays.

Implementation Method 1

the dispersion liquid is irradiated with ultrasonic waves at a frequency of 19.5 kHz and an output of 150 W for 3 minutes

Methodology Applied

Scientific EffectUltrasonic waves: Ultrasound

Implementation Method 2

there has been a tendency to cause problems such as an increase in transmittance of excitation light at a light conversion layer containing the phosphor

Methodology Applied

Scientific EffectLight absorption and emission: Absorption (EM radiation)

Data Source

PatentUS20240002719A1Phosphor particles and light-emitting device

Publication Date: 2024.01.04 DENKA CO LTD

AI summary

Phosphor particles are composed of one or two selected from a powdery phosphor formed of CASN and SCASN, wherein a particle size corresponding to a cumulative 50% is Dx50 and to a cumulative 90% is Dx90 in a volume-based integrated fraction of the phosphor particles, and where a particle size corresponding to a cumulative 50% is Dy50 and to a cumulative 90% is Dy90 after subjecting the particles to treatment, (a) Dx50 is between 0.5 μm and 35 μm, and (b) Dx90/Dy90 is between 0.7 and 15. The treatment; a dispersion liquid wherein 30 mg of the particles are uniformly dispersed in an aqueous solution of sodium hexametaphosphate having a concentration of 0.2% and put into a cylindrical container A vibrator part of an ultrasonic homogenizer is inserted and the liquid is irradiated with ultrasonic waves at a frequency of 19.5 kHz and an output of 150 W for 3 minutes.