Electrochromic Compound for Full-Color Display with Memory Effect

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Solution Overview

Problem

Existing electronic paper technologies face challenges in achieving high white reflectivity and contrast ratio while displaying colors, particularly in forming three primary colors necessary for full-color displays, and they lack a memory effect to retain coloration.

Innovation Solution

An electrochromic compound with a specific structure, represented by General Formula (1), is used, which includes a monovalent binding group, a halogenated carbohydrate group, and a redox chromophore, attached to a conductive or semi-conductive nano structural unit, allowing for a redox reaction that retains coloration for a longer period.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If electrochromic compounds forming three primary colors are used, then full-color display capability is achieved, but memory effect is lost and coloration cannot be retained

Engineering Contradiction:

Improvefull-color display capabilityVSAvoidcoloration retention time

Core Design Contradiction:

Adaptability or versatilityVSDuration of action of moving object

Solution Approach 1:

The patent introduces a specific electrochromic compound structure as an intermediary between the electrode and the color display function. The compound contains a redox chromophore group that can be reversibly oxidized and reduced, and this group is connected to the electrode through a specific molecular structure that provides both coloration capability and memory effect. The compound acts as a mediator that transfers electrons from the electrode to generate colors while retaining the coloration state.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the chemical structure parameters of the electrochromic compound by introducing specific groups (redox chromophore group, electron-withdrawing group, electron-donating group) and adjusting their positions and combinations. This structural parameter change enables the compound to simultaneously achieve full-color display capability through redox reactions and long-term coloration retention through stable molecular configurations that resist spontaneous reversal.

Inventive Principle:

Principle #35Parameter changes

2Illumination intensity

If conventional electrochromic compounds are used, then coloration can be achieved, but the coloration disappears quickly when voltage is removed

Engineering Contradiction:

Improvecoloration intensityVSAvoidcoloration duration

Core Design Contradiction:

Illumination intensityVSDuration of action of moving object

Solution Approach 1:

The patent applies beforehand cushioning by designing the electrochromic compound with stable molecular structures that cushion against spontaneous decoloration. The compound's molecular architecture, including the redox chromophore group connected through specific linkages to electron-withdrawing and electron-donating groups, creates a stable colored state that resists thermal or chemical degradation, thereby cushioning the coloration from fading when voltage is removed.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Power

If organic electrochromic compounds are attached to semiconductor fine particles, then drive voltage and coloration speed are improved, but only blue and green colors can be formed

Engineering Contradiction:

Improvecoloration speedVSAvoidcolor range

Core Design Contradiction:

PowerVSAdaptability or versatility

Solution Approach 1:

The patent applies universality by designing an electrochromic compound that performs multiple functions: it maintains the fast coloration speed achieved by attaching to semiconductor fine particles, while simultaneously expanding the color range to include all three primary colors (cyan, magenta, yellow). The compound's modular structure with adjustable substituents allows it to be tuned for different colors while maintaining efficient electron transfer to the semiconductor particles.

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

The electrochromic device effectively retains and reverses coloration for an extended duration, enhancing image retainability and overcoming the limitations of previous technologies in achieving high white reflectivity and contrast ratio.

Implementation Method 1

A phenomenon in which electrochromic materials applied with a voltage show a reversible color change during the electrochemical redox reaction is called electrochromism

Methodology Applied

Scientific EffectElectrochromism: Electrochromism

Implementation Method 2

electrochromic materials applied with a voltage show a reversible color change during the electrochemical redox reaction

Methodology Applied

Scientific EffectRedox reaction: Redox Reactions

Data Source

PatentUS8080683B2Electrochromic compound and electrochromic display device using the same

Publication Date: 2011.12.20 RICOH CO LTD

AI summary

An electrochromic compound represented by the following General Formula (1).A-(CX2)n—B General Formula (1)In the formula, A is a monovalent binding group, B is a redox chromophore, X is a halogen atom, and n is an integer of 1 or more.