Electrochromic Device Gel Formation Delamination Prevention

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Solution Overview

Problem

Conventional methods for manufacturing electrochromic devices face limitations such as gravitational delamination, liquid phase electrochromic composition, and volume shrinkage during polymerization, which affect the quality and manufacturability of devices, especially those with large interelectrode spaces.

Innovation Solution

A method involving the preparation of a deaerated electrochromic composition as an electrochromic dispersion system with a polymerizable low-shrinkage monomer and highly dispersible polymer, which is then filled into a hermetically closed space between flexible, optically transparent electrodes and sealed, preventing delamination and shrinkage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a liquid phase electrochromic composition is used, then the device can be filled and assembled, but gravitational delamination occurs reducing long-term stability

Engineering Contradiction:

Improveease of filling and assemblyVSAvoidlong-term stability against delamination

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The electrochromic composition undergoes a phase transition from liquid to gel state through in-situ polymerization of monomers (e.g., glycerol trimethacrylate, ethylene glycol dimethacrylate) crosslinked with polyacrylic acid. This phase change occurs after device assembly, transforming the fillable liquid into a stable gel that prevents gravitational delamination while maintaining electrochromic functionality.

Inventive Principle:

Principle #36Phase transitions

Solution Approach 2:

The device is assembled in the liquid phase first, allowing easy filling and sealing. Then, as a subsequent action, polymerization initiators (e.g., benzoyl peroxide, 2,2'-azobis(2-methylpropionamidine) dihydrochloride) are activated to convert the liquid composition into a gel, preventing delamination without requiring pre-gelation that would complicate assembly.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If conventional polymerization is used to thicken the composition, then delamination is reduced, but volume shrinkage adversely affects device quality

Engineering Contradiction:

Improveresistance to delaminationVSAvoiddevice quality and dimensional stability

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent carefully controls polymerization parameters including monomer concentration (5-50 wt%), crosslinker ratio, initiator amount, and polymerization temperature (20-80°C) to minimize volume shrinkage. By optimizing these parameters, the gel formation provides delamination resistance while maintaining dimensional stability and device quality.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The electrochromic composition uses a composite gel system combining polyacrylic acid crosslinked with short-chain polymeric crosslinkers (glycerol trimethacrylate, ethylene glycol dimethacrylate, pentaerythritol tetramethacrylate). This composite structure provides strong network formation for delamination resistance while the short crosslinker chains minimize overall volume shrinkage compared to conventional polymerization systems.

Inventive Principle:

Principle #40Composite materials

3Reliability

If the electrochromic composition is prepared after device assembly, then delamination is prevented, but manufacturability and productivity are reduced

Engineering Contradiction:

Improveprevention of delaminationVSAvoidmanufacturability and production efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent enables continuous manufacturing by performing both device assembly and gel formation in a single production cycle. The liquid electrochromic composition is filled into assembled devices, then polymerization is initiated continuously across multiple devices simultaneously, maintaining production flow while achieving delamination prevention without requiring separate preparation steps.

Inventive Principle:

Principle #20Continuity of useful action

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 approach results in an electrochromic device with long-term stability, uniform coloration and discoloration, and high-voltage control, suitable for large surface areas with minimal shrinkage and improved manufacturability.

Implementation Method 1

a polymerizable low-shrinkage monomer or a monomer mixture, and a polymerization thermal activator

Methodology Applied

Scientific EffectPolymerization: Photopolymerisation

Implementation Method 2

Electrochromism is the physical phenomenon found in certain compositions of reversibly changing predetermined optical properties such as color or light transmittance with an application of an electrical voltage called a control voltage

Methodology Applied

Scientific EffectElectrochromism: Electrochromism

Data Source

PatentUS11698565B2Electrochromic device and method for manufacturing electrochromic device

Publication Date: 2023.07.11 VITRO GLASS GLASS LLC

AI summary

The invention relates to devices that provide a color change under the influence of an electric voltage, in particular to an electrochromic device and a method for manufacturing such a device. Disclosed is the method for manufacturing an electrochromic device comprising at least two electrodes that are flexible and optically transparent with a hermetically closed space between the electrodes filled with an electrochromic composition that may contain transparent and insoluble microparticles that function as spacers.