Viologen Electrochromic Compound for Stable Black Coloring
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Solution Overview
Problem
Viologen-based electrochromic materials suffer from poor solubility and molecular aggregation, leading to stability issues and difficulty in achieving black electrochromic characteristics, as existing technologies rely on mixing blue and green materials which can cause color separation during repeated driving.
Innovation Solution
A new electrochromic compound with improved solubility is synthesized, capable of providing black electrochromic characteristics as a single material, using a specific chemical formula with counter-anions and substituents that adjust discoloration colors, integrated with an electrolyte to form a stable and photocurable composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If viologen-based electrochromic materials are used, then low voltage driving and stability of repeated driving are improved, but solubility deteriorates due to planarity of structure causing molecular aggregation
Solution Approach 1:
The patent introduces specific substituent groups (alkyl, alkoxy, aryl, heteroaryl groups with 1-20 carbons) at localized positions on the viologen core structure. These substituents are strategically placed to provide steric hindrance and improve solubility without compromising the overall electrochromic functionality and redox stability of the viologen system.
Solution Approach 2:
The patent creates composite electrochromic materials by combining viologen core structures with various substituent groups including alkyl chains, alkoxy groups, aryl groups, and heteroaryl groups. This composite approach integrates the electrochemical stability of viologen with the solubility-enhancing properties of diverse organic substituents, achieving both low voltage driving and good solubility.
2Illumination intensity
If blue and green electrochromic materials are mixed to achieve black electrochromism, then black color characteristics are improved, but color separation occurs during repeated driving
Solution Approach 1:
The patent merges blue and green color characteristics into a single viologen-based molecular structure rather than using separate materials. The viologen core with specific substituents simultaneously provides both blue and green electrochromic transitions, achieving black appearance when both transitions are active. This unified structure eliminates color separation issues that occur when mixing separate blue and green materials.
Solution Approach 2:
The patent designs a composite viologen molecule that integrates multiple chromophoric units or substituent groups that contribute different color characteristics (blue and green transitions) within a single molecular framework. This molecular-level composite approach ensures coordinated behavior of all color-generating units, preventing color separation during repeated electrochemical cycling.
3Ease of manufacture
If simple mixing of blue and green materials is used, then manufacturing process is simplified, but it is difficult to satisfy black coordinate required by user
Solution Approach 1:
The patent systematically varies parameters such as substituent type (alkyl, alkoxy, aryl, heteroaryl), substituent position, and chain length to precisely tune the electrochromic characteristics. By adjusting these molecular parameters, the invention achieves accurate black color coordinates (L*<20, a*<5, b*<5 in CIE L*a*b* space) while maintaining manufacturing simplicity through a single-material approach.
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 achieves stable and uniform black electrochromism, enhancing the performance and longevity of electrochromic devices by eliminating the need for mixing blue and green materials, ensuring consistent color retention and improved driving characteristics.
Implementation Method 1
Electrochromism is a well-known physical phenomenon observed for a specific class of compound that reversibly changes a color when a voltage is applied. This material undergoes a reversible change in optical characteristics by oxidation and reduction.
Implementation Method 2
an electrolyte integrated photocurable electrochromic composition
Data Source
AI summary
The present invention relates to an electrochromic compound, and an electrochromic composition and an electrochromic device, including the same. The electrochromic compound according to the present invention may achieve excellent black coloring effects and excellent curing characteristics, and thus may be used advantageously in an electrochromic device.