Semiconductor Nanoparticle Complexes for High-Mass-Fraction Polar Dispersion
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Solution Overview
Problem
Semiconductor nanoparticles are difficult to disperse in polar dispersion media with an SP value of 8.5 or more, leading to reduced luminous efficiency and increased dispersant amount, which hinders their practical application.
Innovation Solution
A semiconductor nanoparticle complex dispersion liquid composed of two or more ligands, including an aliphatic thiol ligand and a polar ligand, coordinated to the nanoparticle surface, allowing dispersion in organic media with an SP value of 8.5 or more, maintaining high fluorescence quantum yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If semiconductor nanoparticles are synthesized in a non-polar dispersion medium, then they can be easily dispersed in a non-polar dispersion medium, but they cannot be dispersed in a polar dispersion medium having an SP value of 8.5 or more
Solution Approach 1:
The patent introduces amphipathic molecules as intermediary substances that bridge the hydrophobic semiconductor nanoparticles and hydrophilic polar dispersion media. These amphipathic molecules have dual nature: one part interacts with the hydrophobic nanoparticle surface while the other part interacts with the hydrophilic dispersion medium, enabling stable dispersion without direct contact between incompatible phases
Solution Approach 2:
The patent modifies the surface properties of semiconductor nanoparticles by changing the chemical composition of ligands coordinated to the nanoparticle surface. By adjusting the polarity, charge, and chemical structure of surface ligands, the nanoparticle surface properties are tuned to match the polarity of the dispersion medium, enabling dispersion in polar media with SP value of 8.5 or more
2Adaptability or versatility
If ligand exchange method is used to make semiconductor nanoparticles dispersible in polar dispersion medium, then they can be dispersed in polar dispersion medium, but luminous efficiency is lowered
Solution Approach 1:
The patent applies different types of ligands to different regions or aspects of the nanoparticle surface: hydrophobic ligands are used to maintain high luminous efficiency and protect the nanoparticle core, while hydrophilic ligands are used specifically at the surface interface to enable dispersion in polar media. This local differentiation allows each ligand type to perform its optimal function without compromising the other
Solution Approach 2:
The patent creates a composite structure on the nanoparticle surface by combining multiple ligand types with different properties. The composite ligand shell includes both hydrophobic components (for maintaining optical properties) and hydrophilic components (for enabling polar medium dispersion), achieving both luminous efficiency and dispersion compatibility simultaneously
3Adaptability or versatility
If encapsulation method is used to make semiconductor nanoparticles dispersible in polar dispersion medium, then they can be dispersed in polar dispersion medium, but the amount of dispersant increases, making it difficult to increase the mass fraction of semiconductor nanoparticles
Solution Approach 1:
The patent performs preliminary modification of the nanoparticle surface by pre-coordinating amphipathic molecules or hydrophilic ligands during the synthesis process. This preliminary surface modification ensures that the nanoparticles are inherently compatible with polar dispersion media from the outset, eliminating the need for subsequent encapsulation steps and reducing the total amount of dispersant required
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 dispersion liquid enables high mass fraction dispersion of semiconductor nanoparticles in polar media while preserving high fluorescence quantum yield, facilitating efficient color conversion and application in displays.
Implementation Method 1
Semiconductor nanoparticles that are so small that a quantum confinement effect is exhibited have a bandgap that depends on the particle diameter. Excitons formed in semiconductor nanoparticles by means of photoexcitation, charge injection, and the like, emit photons with energy corresponding to the band gap by recombination, hence, light emission at a desired wavelength can be obtained by appropriately selecting the composition of the semiconductor nanoparticles and particle diameter thereof.
Implementation Method 2
It is presumed that semiconductor nanoparticles and semiconductor nanoparticle complexes synthesized in a non-polar dispersion medium have a small dipole-dipole force and hydrogen bonding force. Therefore, even among polar dispersion media having an SP value of 8.5 or more, semiconductor nanoparticles can be dispersed in toluene and chloroform, which have small dipole-dipole force and hydrogen bonding force
Implementation Method 3
It is presumed that semiconductor nanoparticles and semiconductor nanoparticle complexes synthesized in a non-polar dispersion medium have a small dipole-dipole force and hydrogen bonding force
Data Source
AI summary
Provided is a semiconductor nanoparticle complex dispersion liquid in which semiconductor nanoparticles are dispersed in a polar dispersion medium at a high mass fraction, and in which high fluorescence quantum efficiency (QY) is maintained. A semiconductor nanoparticle complex dispersion liquid according to an embodiment includes a semiconductor nanoparticle complex dispersed in an organic dispersion medium, wherein: the semiconductor nanoparticle complex is composed of two or more ligands including an aliphatic thiol ligand and a polar ligand, and a semiconductor nanoparticle with the ligands coordinated to the surface thereof; the ligands are composed of an organic group and a coordinating group; the organic group of the polar ligand includes a hydrophilic functional group; and an SP value of the organic dispersion medium is 8.5 or more.