Quantum Dot Conversion Layer Layout for Light Extraction and Heat Control
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Solution Overview
Problem
Existing light emission devices using quantum dots as wavelength conversion materials face challenges in achieving both high light extraction efficiency and reliability, particularly due to increased absorption of excitation light which leads to heat generation and deterioration of quantum dots.
Innovation Solution
A light emission device is designed with a wavelength conversion layer that includes quantum dot phosphors and scattering particles dispersed in a resin. The layer is structured with a first region near the light source unit where only quantum dot phosphors are dispersed, and a second region where both quantum dot phosphors and scattering particles are dispersed. This configuration reduces the absorption coefficient of excitation light near the light source unit, minimizing heat generation and deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If scattering particles are dispersed throughout the wavelength conversion layer to improve light extraction efficiency, then light extraction efficiency is improved, but absorption of excitation light increases near the light source unit causing heat generation and quantum dot deterioration
Solution Approach 1:
The wavelength conversion layer is divided into two distinct regions: a first region closer to the light source unit with lower scattering particle concentration, and a second region farther from the light source unit with higher scattering particle concentration. This segmentation allows the layer to simultaneously achieve good light extraction efficiency while protecting quantum dots from excessive heat near the light source.
Solution Approach 2:
Different regions of the wavelength conversion layer are given different local properties: the first region has lower scattering particle concentration to reduce heat generation near the light source, while the second region has higher scattering particle concentration to enhance light extraction efficiency. This local quality variation resolves the contradiction between the two opposing requirements.
2Productivity
If quantum dot phosphors are dispersed throughout the wavelength conversion layer to convert light wavelength, then wavelength conversion efficiency is improved, but heat generation near the light source unit increases causing deterioration
Solution Approach 1:
The wavelength conversion layer is segmented into regions with different quantum dot phosphor concentrations. The first region near the light source has lower concentration to reduce heat generation, while the second region farther away has higher concentration to maintain overall wavelength conversion efficiency.
Solution Approach 2:
The quantum dot phosphor distribution is made non-uniform with local quality variation: lower concentration near the heat-generating light source and higher concentration in cooler regions, allowing the system to maintain conversion efficiency while managing thermal load.
3Productivity
If the wavelength conversion layer is made thicker to increase light extraction, then light extraction efficiency is improved, but absorption of excitation light increases leading to more heat generation
Solution Approach 1:
The thicker wavelength conversion layer is segmented into regions with varying material concentrations. The first region closer to the light source has optimized concentrations to minimize heat generation, while the second region contributes to light extraction efficiency, allowing the overall layer to be thick without proportionally increasing heat loss.
Solution Approach 2:
Different thickness regions have different local compositions: the first region has lower scattering particle and quantum dot concentrations to reduce absorption and heat generation, while the second region has higher concentrations to enhance light extraction, allowing the layer to be thick overall without excessive energy loss.
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 proposed solution effectively enhances both light extraction efficiency and reliability by reducing the absorption rate of excitation light near the light source unit, thereby minimizing heat-related issues and improving the longevity of quantum dot phosphors.
Implementation Method 1
a plurality of wavelength conversion materials that converts the first light into second light in a different wavelength band
Implementation Method 2
a plurality of scattering particles
Data Source
AI summary
A light emission device according to an embodiment of the present disclosure includes a light source unit and a wavelength conversion layer. The light source unit has a light emission surface and emits first light from the light emission surface. The wavelength conversion layer is disposed on a side of the light emission surface of the light source unit, has a first surface disposed to face the light emission surface and a second surface disposed on an opposite side of the first surface, and includes a plurality of wavelength conversion materials that converts the first light into second light in a different wavelength band and a plurality of scattering particles. The wavelength conversion layer has a lower absorption coefficient of the first light in the vicinity of the first surface than in the vicinity of the second surface.