Phenazine Polymer Electrochromics for Persistent Color Memory

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Solution Overview

Problem

Electrochromic devices face challenges in maintaining a persistent color memory and long-term activation state due to diffusion of anodic and cathodic materials, leading to self-erosion upon removal of charging potential.

Innovation Solution

Incorporating phenazine compounds with sterically hindered groups covalently attached to or confined within polymer matrices, along with viologen compounds, to prevent diffusion and maintain the activated state for extended periods.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If solution-phase electrochromic devices are used, then the device can achieve color change functionality, but the anodic and cathodic materials diffuse and self-erode upon removal of charging potential, preventing persistent color memory

Engineering Contradiction:

Improvepersistent color memoryVSAvoidmaterial diffusion

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent uses polymer films to confine the electrochromic materials. Specifically, a cathodic polymer film containing viologen and a anodic polymer film containing phenazine are deposited on opposing substrates. These flexible polymer films physically constrain the redox species, preventing their diffusion throughout the device while still allowing ion transport necessary for electrochromic operation. This confinement strategy directly addresses the material diffusion problem in solution-phase devices.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The patent employs composite materials by incorporating electrochromic species (viologen, phenazine) within polymer matrices. The polymer provides a solid-phase environment that prevents material diffusion while the embedded electrochromic compounds maintain their redox functionality. This composite structure combines the benefits of solid-phase stability with the electrochromic activity of the organic compounds.

Inventive Principle:

Principle #40Composite materials

2Duration of action of stationary object

If traditional solution-phase electrochromic devices are used, then the device can change color, but the activated state cannot be maintained for extended periods at open circuit

Engineering Contradiction:

Improveactivated state durationVSAvoidcolor memory persistence

Core Design Contradiction:

Duration of action of stationary objectVSReliability

Solution Approach 1:

The polymer films act as barriers that prevent the spontaneous back-diffusion of redox species that would otherwise cause rapid self-discharge. By confining the viologen and phenazine to their respective polymer matrices, the device maintains charge separation and the activated color state for extended periods (days to weeks) at open circuit, enabling persistent color memory functionality.

Inventive Principle:

Principle #30Flexible shells and thin films

3Adaptability or versatility

If electrochromic devices operate under UV exposure and thermal cycling, then the device can function in real-world conditions, but traditional materials degrade rapidly

Engineering Contradiction:

Improveenvironmental durabilityVSAvoidweathering stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The use of polymer-composite materials provides both the electrochromic functionality and enhanced environmental stability. The polymer matrix protects the sensitive viologen and phenazine compounds from direct UV exposure and oxidative degradation, while the crosslinked network structure resists thermal degradation. This composite approach enables the device to maintain performance under UV irradiation and thermal cycling conditions.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The polymer films create a protected, relatively inert microenvironment for the electrochromic species. This physical barrier reduces exposure to oxygen and moisture that would otherwise cause rapid degradation of the organic redox compounds during thermal cycling and UV exposure, thereby improving weathering stability.

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

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 solution enables electrochromic devices to maintain a stable, darkened state for several days at open circuit, with improved durability under UV exposure and thermal cycling, significantly surpassing traditional solution-phase devices.

Implementation Method 1

When a sufficient electrical potential is applied across a pair of electrodes, an electrochromic medium, disposed between the electrodes, may become activated, changing its color and/or light transmissivity

Methodology Applied

Scientific EffectRedox reactions: Redox Reactions

Implementation Method 2

Electrochromic devices have been well known for many years. When a sufficient electrical potential is applied across a pair of electrodes, an electrochromic medium, disposed between the electrodes, may become activated, changing its color and/or light transmissivity

Methodology Applied

Scientific EffectElectrochromism: Electrochromism

Data Source

PatentUS20230266630A1Electrochromic compounds for memory electrochromic devices

Publication Date: 2023.08.24 GENTEX CORP

AI summary

An anodic redox species including a phenazine compound that is substituted with at least one sterically hindered group and an electrochromic device using these chemical compounds are disclosed.