Core-Shell Semiconductor Nanoparticles for Low-Toxicity Band-Edge Emission
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Solution Overview
Problem
Existing semiconductor nanoparticles for light emitting devices face challenges in achieving efficient band edge emission with minimal toxicity and toxicity-related regulatory compliance, particularly in using Cd and Pb-based materials which are toxic and regulated.
Innovation Solution
A method for manufacturing semiconductor nanoparticles comprising silver (Ag), an alkali metal, indium (In), gallium (Ga), and sulfur (S), with a core-shell structure and specific composition ratios, which exhibit band edge emission when irradiated with light, and are free from Cd and Pb, allowing for their use in light emitting devices without toxicity concerns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If CdSe or CdTe quantum dots are used for light emission, then high emission efficiency is achieved, but toxicity increases and regulatory compliance becomes difficult
Solution Approach 1:
The patent changes the compositional parameters by replacing toxic Cd and Pb elements with non-toxic alternatives (In, Ga, S, Se, Te) while adjusting the stoichiometric ratios to achieve the desired emission efficiency. The core semiconductor material uses In-Ga-S/Se/Te composition with specific atomic ratios to maintain quantum dot performance without toxicity
Solution Approach 2:
The patent employs composite material structure with a core-shell configuration where the core contains In-Ga-S/Se/Te semiconductor material and the shell provides protective and functional properties. This composite structure achieves both non-toxicity and high emission efficiency by combining different materials with complementary properties
2Reliability
If PbS or PbSe quantum dots are used for light emission, then high emission efficiency is achieved, but toxicity increases and regulatory compliance becomes difficult
Solution Approach 1:
The patent replaces toxic Pb elements with non-toxic In and Ga elements while adjusting the compositional parameters to achieve the desired emission characteristics. The In-Ga-S/Se/Te core material provides the necessary quantum confinement effects without the toxicity associated with Pb-based materials
3Object-affected harmful factors
If tellurium compound or sulfide nanoparticles are used, then low toxicity is achieved, but emission efficiency and spectral characteristics may be insufficient
Solution Approach 1:
The patent creates a composite core-shell structure where the In-Ga-S/Se/Te core provides efficient band edge emission and the shell enhances stability and emission characteristics. This composite approach allows the use of non-toxic elements while achieving high emission efficiency through synergistic material combinations
Solution Approach 2:
The patent applies local quality by having different regions (core and shell) with different compositions and functions. The core is optimized for light emission with specific In-Ga-S/Se/Te composition, while the shell is optimized for stability and enhanced emission, allowing each region to perform its specific function optimally
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 semiconductor nanoparticles demonstrate efficient band edge emission with a narrow emission spectrum and reduced lattice defects, suitable for applications in light emitting devices, including liquid crystal displays, without the use of toxic materials, thereby addressing regulatory compliance and emission efficiency.
Implementation Method 1
The semiconductor nanoparticle irradiated with light having a wavelength in a range of 200 nm or more and less than 500 nm emits light having an emission peak wavelength in a range of 500 nm to 650 nm
Implementation Method 2
performing a heat treatment of a first mixture containing a silver (Ag) salt, an alkali metal salt, a salt containing at least one of indium (In) and gallium (Ga), a sulfur source, and an organic solvent
Data Source
AI summary
Provided is a method for manufacturing a semiconductor nanoparticle, the method includes performing a heat treatment of a first mixture containing a silver (Ag) salt, an alkali metal salt, a salt containing at least one of indium (In) and gallium (Ga), a sulfur source, and an organic solvent. A ratio of the number of atoms of an alkali metal to the total number of atoms of Ag and the alkali metal in the first mixture is greater than 0 and less than 1.