Neutralized PEDOT:PSS Electrodes for PDLC Durability

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional polymer-dispersed liquid crystal devices using conductive polymer transparent electrodes face issues with durability and manufacturing cost due to acidity-related degradation and complex processing, especially when combined with poly(ethylenedioxythiophene) layers.

Innovation Solution

A method involving the formation of a polymer-dispersed liquid crystal device with neutralized PEDOT:PSS conductive polymer transparent electrodes, where the pH of the PEDOT:PSS aqueous dispersion is adjusted to 4.0-8.0, forming electrode layers through a conductive polymer ink composition and thermal treatment, and curing the polymer-dispersed liquid crystal layer with light irradiation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If poly(ethylenedioxythiophene) conductive polymer is used as transparent electrode material, then manufacturing cost is reduced and flexibility is improved, but the strong acidity causes dissolution and degradation when in direct contact with polymer-dispersed liquid crystal layer

Engineering Contradiction:

Improvemanufacturing costVSAvoiddurability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent introduces an intermediary substance (base compound such as amine, ammonia, or metal hydroxide) that neutralizes the strong acidity of poly(ethylenedioxythiophene) conductive polymer. This intermediary acts as a mediator between the conductive polymer and the polymer-dispersed liquid crystal layer, preventing direct harmful interaction while maintaining the electrode's functionality and the liquid crystal layer's stability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the chemical parameter (pH level) of the conductive polymer by neutralizing its strong acidity. This parameter change transforms the harmful strongly acidic conductive polymer into a neutralized version that is compatible with the polymer-dispersed liquid crystal layer, thereby improving durability without sacrificing the advantages of conductive polymer materials.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If conventional conductive polymer with strong acidity is used, then electrical conductivity is achieved, but the polymer-dispersed liquid crystal layer is damaged and device malfunction occurs

Engineering Contradiction:

Improveelectrical conductivityVSAvoidacidity-related degradation

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful strong acidity of the conductive polymer into a beneficial neutralized state. By intentionally adding base compounds to neutralize the acidity, the patent transforms what was originally a harmful property (strong acidity causing degradation) into a beneficial property (neutralized pH that is compatible with the liquid crystal layer while maintaining conductivity).

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 enhances the durability of the device by preventing damage to the polymer-dispersed liquid crystal layer, allowing for driving voltage comparable to ITO electrodes and superior device performance with improved manufacturing efficiency.

Implementation Method 1

forming a first electrode layer by applying a conductive polymer ink composition including a neutralized PEDOT:PSS aqueous dispersion on a substrate layer and then performing thermal treatment

Methodology Applied

Scientific EffectThermal treatment: Heat Treatment

Implementation Method 2

curing the polymer-dispersed liquid crystal layer via irradiation with a light source

Methodology Applied

Scientific EffectPhotopolymerization: Photopolymerisation

Data Source

PatentUS10642108B2Polymer dispersed-type liquid crystal element comprising neutralized conductive polymer transparent electrode and method for producing same

Publication Date: 2020.05.05 LG CHEM LTD

AI summary

This invention relates to a polymer-dispersed liquid crystal device, including a substrate layer; a neutralized first electrode layer formed on the substrate layer; a polymer-dispersed liquid crystal layer formed on the first electrode layer; a neutralized second electrode layer formed on the polymer-dispersed liquid crystal layer; and a substrate layer formed on the second electrode layer, and to a method of manufacturing the same.