Polyfunctional Ligands for Quantum Dot Ink Stability

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Solution Overview

Problem

Current methods for preparing nanostructure compositions using quantum dots face challenges with ligand stability and optical properties due to the detachment of PEG tails from quantum dot surfaces upon heating or air exposure, leading to performance issues in devices.

Innovation Solution

Development of nanostructure compositions featuring polyfunctional poly(alkylene oxide) ligands with multiple terminal functional groups bound to the surface of nanostructures, which are more stable and improve optical properties when used in nanostructure films.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If PEG-based ligands are used to enable good dispersion in polymer solutions or epoxy monomers, then dispersion quality is improved, but ligand stability deteriorates due to detachment from quantum dot surface upon heating or air exposure

Engineering Contradiction:
Improvedispersion qualityVSAvoidligand stability
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The ligand is segmented into distinct functional regions: a hydrophilic PEG tail for dispersion and a hydrophobic anchor group for stable binding to the quantum dot surface. This segmentation allows each part to perform its specific function optimally without compromising the other.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different parts of the ligand molecule have different chemical properties tailored to specific functions: the PEG tail provides hydrophilicity for dispersion, while the anchor group provides hydrophobicity for stable surface binding. This local differentiation resolves the contradiction between dispersion and stability.

Inventive Principle:
Principle #3Local quality

2Adaptability or versatility

If reactive ligands are used to enable cross-linking with matrix components, then functionality is improved, but complexity increases due to difficulty in design and stabilization

Engineering Contradiction:
Improvecross-linking capabilityVSAvoidligand design complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The ligand is designed with multiple functional groups that provide both cross-linking capability and stable binding. The polyfunctional nature allows a single ligand structure to perform multiple functions: anchoring to quantum dots, providing dispersion, and enabling cross-linking with matrix components.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The ligand incorporates adjustable parameters such as the number and type of functional groups, PEG chain length, and anchor group structure. These parameters can be modified to optimize both cross-linking performance and stability, reducing the need for completely different ligand designs.

Inventive Principle:
Principle #35Parameter changes

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 use of polyfunctional poly(alkylene oxide) ligands enhances the stability and optical performance of nanostructure films, ensuring consistent performance over time and improving the reliability of quantum dot-based devices.

Implementation Method 1

the poly(alkylene oxide) ligand comprises at least two terminal functional groups, wherein at least one terminal functional group is bound to the surface of the nanostructures

Methodology Applied
Scientific EffectSurface binding: Adsorption

Implementation Method 2

Polyethylene glycol (PEG) based ligands enable good dispersion in polymer solutions or the epoxy monomers

Methodology Applied
Scientific EffectDispersion: Dispersion (of waves)

Implementation Method 3

Epoxides and other cyclic ethers, such as oxetanes, are highly strained structures that react easily with nucleophilic reagents such as alcohols, amines, and carboxylic acids to generate cross-linked polymer networks

Methodology Applied
Scientific EffectChemical bonding: Chemical Bonding

Implementation Method 4

which upon heating in the presence of a catalyst, forms a cross-linked thermoset network

Methodology Applied
Scientific EffectThermal reaction: Heating

Data Source

PatentEP3681961B1Application of polyfunctional ligands for improving performance and stability of quantum dot inks
Publication Date: 2023.12.27 SHOEI CHEM IND CO LTD
  • EP3681961B1 patent drawingFigure 1
  • EP3681961B1 patent drawingFigure 2
  • EP3681961B1 patent drawingFigure 3A~3C

AI summary

The present invention provides nanostructure compositions and methods of producing nanostructure compositions. The nanostructure compositions comprise a population of nanostructures comprising polyfunctional poly(alkylene oxide) ligands. The present invention also provides nanostructure films comprising the nanostructure compositions and methods of making nanostructure films using the nanostructure compositions.