Non-uniformly Doped Quantum Dot Core for High Efficiency
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Solution Overview
Problem
Conventional cadmium-based quantum dots have high photoluminescence quantum yields but are toxic, while non-toxic group semiconductor quantum dots like CuInSe2 have low quantum conversion efficiency.
Innovation Solution
A quantum dot with a nanocrystalline core and shell structure, where the core has a sphalerite-type crystal structure and is non-uniformly doped with elements from Group IB, IIIA, and VIA, and the shell includes elements from Group VIA and IIB or IIIA, prepared through a method involving multiple solution preparations and controlled heating and addition of thiol reagents to enhance photoluminescence quantum yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cadmium-based quantum dots are used, then photoluminescence quantum yield is high, but toxicity increases
Solution Approach 1:
The patent changes the chemical composition parameters by replacing cadmium with non-toxic group IIIA and Group VB semiconductor materials (such as InSe, InS, GaSe, GaS) while adjusting the crystal structure from conventional zinc blende to distorted zinc blende or wurtzite structures. This parameter change achieves high photoluminescence quantum yield (>70%) without cadmium toxicity
Solution Approach 2:
The patent creates composite quantum dot structures with core-shell configurations where the core is made of group IIIA-VB semiconductor compounds and the shell consists of similar materials with appropriate lattice matching. This composite structure maintains high photoluminescence efficiency while ensuring non-toxicity through careful material selection and interface engineering
2Object-affected harmful factors
If conventional group semiconductor quantum dots (e.g., CuInSe2) are used, then non-toxicity and stability are achieved, but quantum conversion efficiency remains low
Solution Approach 1:
The patent changes key parameters including crystal structure (distorted zinc blende or wurtzite), composition (group IIIA-VB compounds like InSe, InS, GaSe, GaS), and surface chemistry (thiol ligand coordination). These parameter changes transform conventional low-efficiency group semiconductor quantum dots into high-efficiency emitters with photoluminescence quantum yield exceeding 70% while maintaining non-toxicity
Solution Approach 2:
The patent applies local quality optimization through core-shell structure engineering where the core provides the desired optical properties and the shell provides surface passivation and stability. The thiol ligand coordination at surfaces creates localized high-quality interfaces that enhance quantum conversion efficiency by reducing non-radiative recombination pathways
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 approach results in quantum dots with photoluminescence quantum yields greater than 70% and wavelengths over 700 nm, significantly improving efficiency compared to conventional dots.
Implementation Method 1
Quantum dots are excited by light or electricity can emit light of different wavelengths depending on the band gap energy thereof
Implementation Method 2
swiftly injecting a TOPSe stock solution (selenium (Se) precursor) to replace sulfur (S) of Cu—S and In—S with Se
Data Source
AI summary
A quantum dot includes a nanocrystalline core and a nanocrystalline shell. The nanocrystalline core includes a core body and a doping material that is non-uniformly doped in the core body. The core body has a sphalerite-type crystal structure, and includes at least one element from Group IB, at least one element from Group IIIA and at least one element from Group VIA. The doping material includes at least one doping element selected from the group consisting of an element from Group IB, an element from Group IIB and an element from Group IIIA. The nanocrystalline shell surrounds the nanocrystalline core and includes at least one element from Group VIA, and at least one element from one of Group IIB and Group IIIA. A method for preparing the quantum dot is also disclosed.