Non-stoichiometric Quantum Dots for Mid-Infrared Emission
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Solution Overview
Problem
Existing quantum dots struggle to emit mid-infrared or far-infrared rays due to their large band gap, and the ligand substitution for photoelectronic applications using thiol organic ligands is not easily facilitated.
Innovation Solution
Non-stoichiometric quantum dot nanoparticles with HgS cores and nonthiol ligands such as oleic acid or oleylamine are used, which emit infrared rays through electron transitions between discrete energy levels in the band, and a method involving heating a mercury precursor solution with nonthiol ligands and mixing it with a chalcogen precursor solution is employed to synthesize these nanoparticles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional quantum dots with stoichiometric composition are used, then the quantum dot maintains a stable structure with defined band gap, but it cannot emit mid-infrared or far-infrared rays due to large band gap
Solution Approach 1:
The patent changes the compositional parameter of the quantum dot from stoichiometric to non-stoichiometric (excess metal atoms), which fundamentally alters the electronic structure and enables mid-infrared and far-infrared emission while maintaining colloidal stability through surface passivation
2Stability of the object's composition
If thiol organic ligands are used to stabilize quantum dots, then the quantum dot maintains colloidal stability, but ligand substitution for photoelectronic applications becomes difficult
Solution Approach 1:
The patent extracts the thiol ligands from the quantum dot surface and replaces them with non-thiol ligands such as phosphonic acid, carboxylic acid, or amine ligands. This extraction removes the harmful binding特性 of thiol ligands while maintaining colloidal stability through alternative surface passivation mechanisms
Solution Approach 2:
The patent changes the chemical nature of the surface ligands from thiol-based to non-thiol-based compounds, which fundamentally alters the surface chemistry and enables easier ligand substitution while preserving colloidal stability through different binding mechanisms
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 non-stoichiometric quantum dot nanoparticles effectively emit mid-infrared or far-infrared rays, and the use of nonthiol ligands simplifies ligand substitution, maintaining n-type doping and facilitating easier integration into photoelectronic devices.
Implementation Method 1
emit infrared rays from electron transition between discrete energy levels in the band
Implementation Method 2
exhibits quantum confinement effect. When the quantum dot is stimulated by an energy such as light, the quantum dot emits light
Data Source
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AI summary
The present invention relates to an infrared device using intra-band electron transition of non-stoichiometric quantum dots and, more specifically, to non-stoichiometric quantum dot nanoparticles and an infrared device comprising the nanoparticles, in which the nanoparticles comprise quantum dot cores and nonthiol ligands bonded to the core and emits infrared rays from electron transition between discrete energy levels in the band. The infrared device according to the present invention has an effect of emitting infrared rays, particularly, mid-infrared rays or far-infrared rays, by using the electron transition between discrete energy levels in the band of quantum dots in which the proportion of a metal is higher than that of a chalcogen. In addition, the quantum dots are prepared by containing nonthiol ligands, and thus, compared with a conventional thiol ligand, ligand substitution is very easy while the n-type doping of quantum dots is maintained. A positive or negative voltage is applied to non-stoichiometric quantum dots, and thus, the transmittance of the light incident to the quantum dots is reversibly controlled.