Quantum Dot Ink Composition for High-Viscosity EHD Printing

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Solution Overview

Problem

Existing quantum dot compositions for electrohydrodynamic inkjet printing face challenges with high viscosity, agglomeration, and poor light conversion efficiency, which hinder their application in display devices.

Innovation Solution

A quantum dot composition comprising quantum dots, a photopolymerizable monomer, and an oligomer with specific carbon-carbon double bond and thiol group compounds, along with surface modification using primary and secondary ligands, to achieve high viscosity, electrical conductivity, and prevent agglomeration, suitable for electrohydrodynamic inkjet printing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If quantum dots are dispersed in a polymer matrix for inkjet printing, then the composition can be applied to displays, but the viscosity becomes too low requiring solvent evaporation which prolongs processing time

Engineering Contradiction:

Improveinkjet printing applicabilityVSAvoidprocessing time

Core Design Contradiction:

Ease of operationVSLoss of time

Solution Approach 1:

The patent changes the viscosity parameter of the quantum dot composition by selecting specific oligomers with appropriate molecular weights and functionalities, achieving suitable viscosity (100-10,000 cps) without requiring solvent evaporation or heating processes

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite system combining quantum dots with specific oligomers (containing carbon-carbon double bonds and thiol groups) and photopolymerizable monomers, where the oligomer composition is optimized to achieve both proper viscosity and prevention of quantum dot agglomeration

Inventive Principle:

Principle #40Composite materials

2Use of energy by moving object

If quantum dot concentration is increased to improve light conversion efficiency, then optical properties improve, but quantum dots agglomerate reducing performance

Engineering Contradiction:

Improvelight conversion efficiencyVSAvoidquantum dot dispersion stability

Core Design Contradiction:

Use of energy by moving objectVSStability of the object's composition

Solution Approach 1:

The patent uses oligomers containing thiol groups as intermediary substances that bind to quantum dot surfaces, preventing direct quantum dot-to-quantum dot contact and agglomeration while maintaining high quantum dot concentrations for optimal light conversion efficiency

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent optimizes the concentration parameter of quantum dots within a specific range (1-50 wt%, preferably 5-20 wt%) and adjusts oligomer composition to maintain stable dispersion at these concentrations, achieving high light conversion efficiency without agglomeration

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If viscosity is increased to improve ejectability in electrohydrodynamic inkjet printing, then printing performance improves, but quantum dot agglomeration occurs

Engineering Contradiction:

ImproveejectabilityVSAvoidquantum dot dispersion stability

Core Design Contradiction:

Ease of operationVSStability of the object's composition

Solution Approach 1:

The patent develops a composite formulation where quantum dots are dispersed in a matrix of photopolymerizable monomers and specific oligomers, achieving the viscosity range of 100-10,000 cps suitable for EHD inkjet printing while the oligomer components prevent quantum dot agglomeration through surface interaction

Inventive Principle:

Principle #40Composite materials

4Loss of substance

If conventional inkjet methods are used to reduce material waste, then material efficiency improves, but viscosity requirements limit composition design options

Engineering Contradiction:

Improvematerial wasteVSAvoidcomposition design flexibility

Core Design Contradiction:

Loss of substanceVSAdaptability or versatility

Solution Approach 1:

The patent changes the viscosity parameter from the conventional requirement of ≤100 cps to a higher range of 100-10,000 cps by using specific oligomers, expanding composition design flexibility while maintaining compatibility with inkjet printing methods and preventing quantum dot agglomeration

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 composition enables stable, high-viscosity quantum dot inks with excellent optical properties and inkjetting properties, reducing material waste and improving light conversion efficiency in display devices.

Implementation Method 1

a photopolymerizable monomer, and an oligomer, wherein the oligomer includes a compound containing a carbon-carbon double bond and a compound containing a thiol group

Methodology Applied

Scientific EffectPhotopolymerization: Photopolymerisation

Data Source

PatentEP4442790B1Quantum dot composition, method of preparing the same, cured product thereof, and display device including the same

Publication Date: 2026.05.20 SAMSUNG ELECTRONICS CO LTD

Figure 1

AI summary

A quantum dot composition including quantum dots, a photopolymerizable monomer, and an oligomer, wherein the oligomer includes a compound containing a carbon-carbon double bond and a compound containing a thiol group.