Phosphor Powder Particle Size Distribution for Micro-LED Absorption
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Solution Overview
Problem
Conventional phosphors for micro-LED displays face challenges in achieving high emission intensity and color quality due to low absorption rates and quantum efficiencies, particularly with thin phosphor layers that need to absorb nearly all blue emission efficiently.
Innovation Solution
A phosphor powder with a specific particle size distribution, including fine and medium-diameter particles, is developed to enhance absorption rates and internal quantum efficiency, characterized by a cumulative volume frequency of fine particles between 10% and 90%, a D50 of 10.0 μm or less, and a broad particle size distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a thin phosphor layer is used in micro-LED displays, then the device structure is compact and resolution is high, but the absorption rate of blue light becomes insufficient
Solution Approach 1:
The invention changes the particle size parameter of the phosphor powder from conventional single-size distribution to a specific multi-size distribution (D10: 1-3 μm, D50: 5-10 μm, D90: 10-20 μm). This parameter change allows the thin phosphor layer to achieve high absorption rate by optimizing the cumulative volume frequency of particles across different size ranges, resolving the contradiction between thin layer structure and sufficient light absorption.
2Reliability
If phosphor particles are made finer to increase absorption rate, then absorption improves, but internal quantum efficiency decreases due to excessive fine particles
Solution Approach 1:
The invention applies local quality by differentiating the functional roles of particles with different size ranges within the phosphor powder. Fine particles (D10: 1-3 μm) are optimized for absorption rate contribution, while medium particles (D50: 5-10 μm) are optimized for maintaining internal quantum efficiency. This local differentiation of particle functions resolves the contradiction between absorption rate and quantum efficiency.
Solution Approach 2:
The invention creates a composite phosphor powder system combining particles of multiple size ranges (fine and medium particles) in specific proportions. This composite structure allows the material to simultaneously achieve high absorption rate from fine particles and high internal quantum efficiency from medium particles, resolving the trade-off between these two properties.
3Ease of manufacture
If conventional phosphor powders are used, then manufacturing is simple, but emission intensity and color quality are insufficient
Solution Approach 1:
The invention changes the particle size distribution parameters of the phosphor powder to achieve optimal emission performance. By controlling D10, D50, and D90 values within specific ranges and setting cumulative volume frequencies, the phosphor powder achieves high emission intensity and color quality while maintaining manufacturability through conventional powder preparation techniques.
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 solution results in a phosphor powder with high absorption rates and internal quantum efficiency, leading to improved emission intensity and color quality in LED packages, suitable for mini-LED and micro-LED displays.
Implementation Method 1
the phosphor absorbs the light (emission) from the LED and emits light with a wavelength different from that of the absorbed light
Data Source
AI summary
Provided are a phosphor powder having a sufficiently high absorption rate and high internal quantum efficiency, a phosphor-containing composition, a light-emitting element, and a light-emitting device. The phosphor powder is such that the total volume frequency of particles having a grain size of less than 2.5 μm as measured by a laser diffraction scattering grain size distribution measurement method is 10% or greater, the total volume frequency of particles having a grain size of 2.5-10 μm is 10-90%, and the cumulative 50% diameter (D50) in the volume grain size distribution is 10.0 μm or less.