Electrochromic Element Preventing Color Remaining via Segmented Redox Layers

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Solution Overview

Problem

Existing electrochromic elements (EC elements) suffer from color remaining, which is the failure to return to the initial state after being driven to change colors, affecting their reliability, especially when used for light control.

Innovation Solution

The electrochromic element is designed with a specific configuration that includes a first electrode, a second electrode, an electrolyte layer containing an oxidizable or reducible substance, and electrochromic layers. By applying a voltage for returning to the initial state, the oxidizable or reducible substance undergoes an oxidation-reduction reaction, allowing the EC element to return to its initial state without sensing color remaining.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If an electrochromic element is driven to change colors, then the color development function is improved, but color remaining occurs and reliability deteriorates

Engineering Contradiction:
Improvecolor developmentVSAvoidcolor remaining
Core Design Contradiction:
Illumination intensityVSReliability

Solution Approach 1:

The patent divides the electrochromic element into two separate electrochromic layers: a first electrochromic layer containing an oxidizable electrochromic compound and a second electrochromic layer containing a reducible electrochromic compound. Each layer is positioned between the electrodes and can undergo color changes independently through oxidation or reduction reactions, allowing the system to achieve full color modulation while preventing color remaining through complementary reactions

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent combines two electrochromic layers with opposite color change mechanisms (oxidation and reduction) into a single electrochromic element. The first electrochromic layer undergoes oxidation to change color, while the second electrochromic layer undergoes reduction to change color in the opposite direction. This merging of complementary mechanisms allows the element to achieve reliable color control without color remaining

Inventive Principle:
Principle #5Merging (Combining)

2Reliability

If an electrochromic element uses oxidizable and reducible substances in electrolyte, then color remaining is reduced, but device complexity increases

Engineering Contradiction:
Improvecolor remainingVSAvoidstructure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the electrochromic functional materials into two distinct layers: a first electrochromic layer containing oxidizable electrochromic compounds and a second electrochromic layer containing reducible electrochromic compounds. Each layer is positioned between the electrodes and can undergo color changes independently through oxidation or reduction reactions, allowing the system to achieve full color modulation while preventing color remaining through complementary reactions

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The electrolyte layer serves multiple functions: it provides ionic conductivity for charge transport, contains oxidizable and reducible substances that facilitate reversible color changes, and enables both oxidation and reduction reactions to occur within the same element. This multi-functionality reduces the need for separate components while maintaining reliability

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

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 configuration enables the electrochromic element to maintain high memory performance and prevent color remaining, ensuring reliable operation and efficient color development and decolorization.

Implementation Method 1

an oxidizable or reducible substance, and electrochromic layers. By applying a voltage for returning to the initial state, the oxidizable or reducible substance undergoes an oxidation-reduction reaction

Methodology Applied
Scientific EffectOxidation-reduction reaction: Redox Reactions

Implementation Method 2

an oxidizable electrochromic layer between the first electrode and the electrolyte layer, containing an oxidizable electrochromic compound; and a reducible electrochromic layer between the second electrode and the electrolyte layer, containing a reducible electrochromic compound

Methodology Applied
Scientific EffectOxidation-reduction reaction: Redox Reactions

Implementation Method 3

Electrochromism is a phenomenon that in response to application of a voltage, a substance undergoes an oxidation-reduction reaction reversibly and changes colors

Methodology Applied
Scientific EffectElectrochromism: Electrochromism

Data Source

PatentEP3945363B1Electrochromic element and method of driving the same
Publication Date: 2025.04.23 RICOH CO LTD
  • EP3945363B1 patent drawingFigure 1~2
  • EP3945363B1 patent drawingFigure 3
  • EP3945363B1 patent drawing

AI summary

Provided is an electrochromic element including: a first electrode (1); a second electrode (2) apart from and opposite to the first electrode (1); an electrolyte layer (5) between the first electrode (1) and the second electrode (2), containing an oxidizable substance or a reducible substance, or both; and at least one of an oxidizable electrochromic layer (6) between the first electrode (1) and the electrolyte layer (5), containing an oxidizable electrochromic compound, and reducible electrochromic layer (9) between the second electrode (2) and the electrolyte layer (5), containing a reducible electrochromic compound, wherein an oxidation potential of the oxidizable substance is nobler than an oxidation potential of the oxidizable electrochromic compound, a reduction potential of the reducible substance is baser than a reduction potential of the reducible electrochromic compound, an oxidation reaction of the oxidizable substance is irreversible, and a reduction reaction of the reducible substance is irreversible.