Metal Oxide Nanocrystal Production via Segmented Flow

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Solution Overview

Problem

Current methods for producing electrochromic nanocrystals for smart windows face challenges in achieving rapid bias switching, high coloration efficiency, and stability, with issues related to size dispersion, homogeneity, and ligand exchange, particularly in large-scale production and commercial applications.

Innovation Solution

A continuous flow method involving the use of segmented reaction flows, thermal processing, and ligand exchange in a continuous flow reactor to produce metal oxide nanocrystals with uniform sizes and controlled ligand binding, ensuring consistent optical properties and spectral tuning range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If batch production methods are used for nanocrystals, then production flexibility is maintained, but size dispersion and homogeneity deteriorate

Engineering Contradiction:
Improvenanocrystal size uniformityVSAvoidproduction scalability
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The batch production process is segmented into discrete continuous flow stages: precursor mixing in a first reactor, thermal processing in a second reactor, and ligand exchange in a third reactor. This segmentation allows each stage to be optimized independently, achieving narrow size distribution through controlled reaction conditions while maintaining high productivity through continuous operation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention implements continuous flow production where reactants continuously flow through multiple reactors in sequence. The nanocrystal precursor solution is continuously mixed, heated, and processed through thermal treatment and ligand exchange without batch interruptions. This continuous action eliminates the size dispersion inherent in batch methods while sustaining high production rates.

Inventive Principle:
Principle #20Continuity of useful action

2Reliability

If complex ligand exchange processes are used, then nanocrystal stability improves, but production time and complexity increase

Engineering Contradiction:
Improvenanocrystal stabilityVSAvoidligand exchange time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The ligand exchange process is initiated immediately after nanocrystal formation in the second reactor, without any intermediate storage or processing steps. The nanocrystals flow directly into the third reactor where ligand exchange occurs continuously. This preliminary action eliminates idle time and ensures that stabilizing ligands are attached before any potential aggregation or degradation occurs.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention merges the nanocrystal synthesis and ligand exchange processes into a single continuous flow sequence. The thermal processing reactor (second reactor) and ligand exchange reactor (third reactor) are connected in series, allowing nanocrystals to transition directly from formation to stabilization. This merging eliminates separate processing steps and reduces total production time while maintaining nanocrystal stability.

Inventive Principle:
Principle #5Merging (Combining)

3Manufacturing precision

If multiple production parameters are adjusted for optimal nanocrystal properties, then optical quality improves, but process complexity increases

Engineering Contradiction:
Improveoptical property consistencyVSAvoidprocess control complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The invention optimizes nanocrystal optical properties by systematically controlling key parameters: precursor concentration and flow rate in the first reactor, temperature and residence time in the second reactor, and ligand type and concentration in the third reactor. These parameter changes are implemented through the continuous flow system design rather than complex post-processing adjustments, achieving consistent optical quality with simplified process control.

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

This method enables the production of nanocrystals with small particle size distribution and efficient ligand exchange, enhancing the performance and reliability of electrochromic materials for smart windows by ensuring consistent size and optical properties across batches.

Implementation Method 1

heating the segmented reaction flow in the thermal processor to create a product flow

Methodology Applied
Scientific EffectThermal processing: Heating

Implementation Method 2

Coordinating ligands bound to the surface of the nanoparticles may provide a wide variety of properties to the nanoparticles

Methodology Applied
Scientific EffectLigand exchange: Adsorption

Data Source

PatentEP3326976B1Metal oxide nanocrystal production method
Publication Date: 2021.09.01 SHOEI CHEM IND CO LTD
  • EP3326976B1 patent drawingFigure 1
  • EP3326976B1 patent drawingFigure 2A~2B
  • EP3326976B1 patent drawingFigure 3A

AI summary

A method for producing metal oxide nanocrystals, according to the embodiment of the present invention, includes: continuously flowing, into a continuous flow path, one or a plurality of nanocrystal precursor solutions each comprising one or more nanocrystal precursors dissolved in a non-polar solvent; directing a segmenting gas into the continuous flow path to create a segmented reaction flow; flowing the segmented reaction flow into a thermal processor; heating the segmented reaction flow in the thermal processor to create a product flow; and collecting metal oxide nanocrystals from the product flow.