Cadmium-Free Quantum Dot Multishells for Stable Blue-Light Luminescence

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Solution Overview

Problem

Cadmium-based quantum dots face environmental and health concerns, and cadmium-free quantum dots suffer from insufficient luminescence properties and stability, particularly in blue light absorption, leading to reduced luminance and increased manufacturing costs in display devices.

Innovation Solution

A quantum dot structure comprising a core of a first semiconductor nanocrystal, a first shell of a Group III-VI compound, and a second shell of a Group II-VI compound, with controlled effective mass ratios and layer compositions to enhance excitation light absorption and reduce full width at half maximum (FWHM).

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If cadmium-based quantum dots are used, then luminescence properties and stability are improved, but environmental and health concerns arise

Engineering Contradiction:

Improveluminescence stabilityVSAvoidenvironmental and health concerns

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent removes cadmium from the quantum dot composition entirely, extracting the harmful element while maintaining the functional structure through alternative materials (Group III-V and Group II-VI compounds) that provide similar luminescence properties without the toxic effects

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent employs composite material structures with multiple shells containing different Group III-V and Group II-VI compounds, creating a multi-layered composite that achieves both non-toxicity and enhanced luminescence stability through synergistic material combinations

Inventive Principle:

Principle #40Composite materials

2Object-affected harmful factors

If cadmium-free quantum dots are used, then environmental concerns are addressed, but luminescence properties and stability deteriorate

Engineering Contradiction:

Improveenvironmental safetyVSAvoidluminescence stability

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent uses composite material structures with multiple shells containing different Group III-V and Group II-VI compounds, creating a multi-layered composite that achieves both non-toxicity and enhanced luminescence stability through synergistic material combinations

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent optimizes physical and chemical parameters including shell thickness ratios, composition ratios of Group III-V and Group II-VI compounds, and crystal structure parameters to maximize luminescence stability while maintaining cadmium-free composition

Inventive Principle:

Principle #35Parameter changes

3Illumination intensity

If quantum dot structure is optimized for blue light absorption, then luminance is improved, but manufacturing costs increase

Engineering Contradiction:

ImproveluminanceVSAvoidmanufacturing cost

Core Design Contradiction:

Illumination intensityVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies different material compositions and structural characteristics to different regions (inner shell vs. outer shell) to optimize blue light absorption and luminance performance in specific areas where it is most needed, rather than uniformly across the entire structure

Inventive Principle:

Principle #3Local quality

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 structure achieves improved luminous efficiency and reduced FWHM, addressing the limitations of cadmium-free quantum dots by enhancing absorption rates and stability without increasing manufacturing costs.

Implementation Method 1

Quantum dots may absorb light from an excitation source to be excited, and may emit energy corresponding to bandgap energies on the quantum dots

Methodology Applied

Scientific EffectPhotoluminescence: Photoluminescence

Implementation Method 2

Such semiconductor nanocrystal particles have such a small size that they have a large surface area per unit volume and exhibit quantum confinement effects

Methodology Applied

Scientific EffectQuantum confinement effect:

Data Source

PatentUS12371617B2Quantum dots, quantum dot-polymer composite, and electronic device including the same

Publication Date: 2025.07.29 SAMSUNG ELECTRONICS CO LTD

AI summary

A quantum dot, a quantum dot-polymer composite, and an electronic device including the same. The quantum dot includes a core including a first semiconductor nanocrystal; a first shell including a second semiconductor nanocrystal including a Group III-VI compound on the core; and a second shell including a third semiconductor nanocrystal having a composition different from that of the second semiconductor nanocrystal on the first shell; wherein one of the first semiconductor nanocrystal and the third semiconductor nanocrystal includes a Group III-V compound.