Copper-Based Core-Shell Quantum Dots for Narrow Emission
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Solution Overview
Problem
Existing quantum dots used in optical members and electronic apparatuses face challenges in achieving high quantum yield without toxic elements like cadmium and ensuring narrow emission spectra for improved color purity and viewing angles.
Innovation Solution
A quantum dot comprising a core of copper, a Group III element, and a Group VI element, with a full width at half maximum (FWHM) of the emission wavelength spectrum less than 55 nm, and a first shell made of Group II-VI, Group III-VI, or Group III-V semiconductor compounds, enhancing quantum yield to over 70% and improving color purity and viewing angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If quantum dots use cadmium for high quantum yield, then quantum yield is improved, but toxicity increases
Solution Approach 1:
The patent changes the compositional parameters by replacing cadmium with copper and adjusting the stoichiometry to CuInGaS2, achieving high quantum yield without toxicity while maintaining optical performance
Solution Approach 2:
The patent uses a composite material system combining copper, indium, gallium, and sulfur to create quantum dots that achieve both high quantum yield and non-toxicity, replacing traditional cadmium-based materials
2Ease of manufacture
If quantum dot emission spectrum is broad, then manufacturing is easier, but color purity deteriorates
Solution Approach 1:
The patent optimizes compositional parameters (Cu:In:Ga:S ratio) and synthesis conditions to achieve a balanced emission spectrum that is both manufacturable and spectrally pure, with FWHM between 30-60 nm
Solution Approach 2:
The patent creates local compositional variations and gradients within the quantum dot structure to control emission characteristics, achieving narrow FWHM while maintaining ease of manufacture
3Manufacturing precision
If quantum dot FWHM is reduced for narrow emission, then color purity is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent establishes specific compositional ranges (Cu: 4-10 at%, In: 10-20 at%, Ga: 30-40 at%, S: 40-50 at%) and synthesis temperature ranges (240-320°C) that simultaneously achieve narrow FWHM and manageable manufacturing precision
Solution Approach 2:
The patent allows for partial compositional deviations within defined ranges while maintaining the target FWHM, reducing the stringency of manufacturing precision requirements while still achieving acceptable color purity
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 quantum dot achieves high quantum yield, narrow emission spectra, and improved color reproducibility, enabling better performance in optical members and electronic apparatuses.
Implementation Method 1
Quantum dots, which are semiconductor nanocrystals with a quantum confinement effect, may have different energy bandgaps by control of the size and composition of the nanocrystals, and thus may emit light of various emission wavelengths
Implementation Method 2
quantum dots that have excellent quantum yield (QY) and do not include cadmium
Data Source
AI summary
Embodiments provide a quantum dot, an optical member including the quantum dot, an electronic apparatus including the quantum dot, and a method of manufacturing the quantum dot. The quantum dot includes: a core including copper (Cu), a Group III element, and a Group VI element; and a first shell covering the core. A full width at half maximum (FWHM) of an emission wavelength spectrum of the core is equal to or less than about 55 nm.