Anisotropic Light Scattering Layer for Quantum Dot Optical Conversion
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Solution Overview
Problem
Current optical conversion members using quantum dots face challenges in achieving high light extraction efficiency due to increased effective optical path lengths, which lead to re-absorption of fluorescent light, thereby reducing light extraction efficiency.
Innovation Solution
An optical conversion member is developed with an anisotropic light scattering layer having a specific transmission light intensity ratio (I(0°)/I(40°) of greater than or equal to 3, which scatters light in a manner that reduces the effective optical path length and enhances light extraction efficiency by preferentially scattering light towards the visible side.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sheet type optical conversion member is used, then stability of the quantum dot is improved, but light extraction efficiency deteriorates due to waveguide mode total reflection
Solution Approach 1:
The patent introduces a light scattering layer as an intermediary component between the quantum dot layer and the air interface. This scattering layer mediates the interaction between light and the quantum dots by disrupting the waveguide mode propagation through scattering effects, thereby enabling light extraction without compromising the stability of the quantum dot structure.
Solution Approach 2:
The light scattering layer is constructed with a porous or heterogeneous structure containing scattering particles distributed within a resin matrix. This porous configuration creates multiple interfaces and scattering centers that effectively disrupt total internal reflection, allowing trapped waveguide modes to escape while maintaining the integrity of the underlying quantum dot layer.
2Illumination intensity
If the effective optical path length is increased to enhance light absorption, then light emission intensity improves, but re-absorption of fluorescent light increases, reducing light extraction efficiency
Solution Approach 1:
The patent segments the optical conversion member into functionally distinct layers: a quantum dot layer for light emission and a separate light scattering layer for light extraction enhancement. This segmentation allows the quantum dot layer to maintain optimal thickness for light absorption and emission intensity, while the scattering layer independently addresses the light extraction problem by redirecting emitted photons out of the waveguide mode without increasing the quantum dot layer thickness and causing re-absorption.
3Manufacturing precision
If quantum dots are used to improve color reproducibility, then color reproduction range increases, but cost increases due to expensive quantum dot material
Solution Approach 1:
The patent optimizes the parameters of the light scattering layer, specifically controlling the size, concentration, and distribution of scattering particles, as well as the thickness of the scattering layer. By carefully adjusting these parameters, the system achieves maximum light extraction efficiency with minimal quantum dot material, thereby reducing costs while preserving the excellent color reproducibility provided by the quantum dots.
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 anisotropic light scattering layer effectively increases the light extraction efficiency of the optical conversion member by minimizing re-absorption and optimizing light scattering, leading to improved brightness and color reproducibility in liquid crystal display devices.
Implementation Method 1
an anisotropic light scattering layer having I (0°)/I (40°) of greater than or equal to 3... scatters light in a manner that reduces the effective optical path length
Implementation Method 2
the quantum dot is excited and emits fluorescent light
Data Source
AI summary
Disclosed is an optical conversion member, including an optical conversion layer containing quantum dot emitting fluorescent light and an anisotropic light scattering layer having I (0°)/I (40°) of 3 or greater, in which I (0°) indicates a transmission light intensity of the anisotropic light scattering layer at the time of allowing light to be incident on the anisotropic light scattering layer from a normal direction of a surface of the anisotropic light scattering layer, and I (40°) indicates a transmission light intensity of the anisotropic light scattering layer in an azimuth in which a transmission light intensity of the anisotropic light scattering layer at the time of allowing light to be incident on the anisotropic light scattering layer from a direction of a tilt angle of 40° with respect to the normal direction of the surface of the anisotropic light scattering layer becomes a minimum value.