Core Shell Particle Surface Modification for UV Durability
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Solution Overview
Problem
Semiconductor nanoparticles, particularly core shell particles, face issues with luminous efficacy and durability, especially when exposed to ultraviolet rays, due to surface defects and exciton trapping, which affect their performance in applications like light-emitting devices.
Innovation Solution
A core shell particle design incorporating a core with Group III and Group V elements, coated with multiple shells and a metal-containing organic compound with a hydrocarbon group, specifically a fatty acid metal salt, to enhance luminous efficacy and durability by reducing surface defects and exciton trapping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If core shell particles are used for light-emitting applications, then luminous efficacy can be improved, but durability under ultraviolet exposure deteriorates due to surface defects and exciton trapping
Solution Approach 1:
The patent divides the shell into multiple layers (first shell and second shell) with different compositions and functions. The first shell (e.g., ZnS) provides a wide band gap to confine excitons, while the second shell (e.g., GaP) offers lattice matching to reduce defects. This segmented structure allows each layer to optimize for its specific function, resolving the contradiction between luminous efficacy and durability.
Solution Approach 2:
The patent employs composite materials combining different semiconductor compounds (Group II-VI and Group III-V) in a core-shell structure. The core (e.g., InP) provides high luminous efficacy, while the composite shell structure (multiple layers with different band gaps and lattice constants) provides durability by reducing surface defects and preventing exciton trapping. This composite approach enables simultaneous optimization of both properties.
2Illumination intensity
If particle diameter is decreased to achieve quantum size effects, then band gap increases and short wavelength emission is achieved, but surface defects increase leading to reduced durability
Solution Approach 1:
The patent uses a nested structure where the core nanoparticle is embedded within multiple shell layers. This nested configuration protects the small-diameter core (which provides quantum size effects and controlled emission wavelength) from direct exposure to the environment, reducing surface defect impacts. The shells act as protective layers that maintain durability while preserving the core's optical properties.
Solution Approach 2:
The patent applies different material compositions and structural qualities to different regions: the core maintains small diameter for quantum effects, the first shell provides wide band gap for exciton confinement, and the second shell provides lattice matching for defect reduction. This local quality differentiation allows each region to optimize for its specific function, resolving the contradiction between size-dependent optical properties and durability.
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 significantly improves the luminous efficacy and durability of core shell particles, maintaining high performance even after exposure to ultraviolet radiation, making them suitable for applications in quantum dots and wavelength conversion films.
Implementation Method 1
at least a part of a surface of the core shell particle contains a metal-containing organic compound containing a metal element and a hydrocarbon group... the luminous efficacy is high and the durability is excellent
Data Source
AI summary
An object of the present invention is to provide a core shell particle having high luminous efficacy and excellent durability; a method of producing the same; and a film obtained by using the core shell particle. The core shell particle of the present invention includes: a core which contains a Group III element and a Group V element; a first shell which covers at least a part of a surface of the core; and a second shell which covers at least a part of the first shell, in which at least a part of a surface of the core shell particle contains a metal-containing organic compound containing a metal element and a hydrocarbon group.