Black-to-Transmissive Electrochromic Device via Redox-Active Material
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Solution Overview
Problem
Current black-to-transmissive electrochromic devices using Co-based metallo-supramolecules, such as PolyCo, face challenges in achieving a fully colorless transmissive state and are limited to aqueous systems, with insufficient self-electron-exchange ability and mechanical durability issues.
Innovation Solution
Incorporating a redox-active material like K3Fe(CN)6, ferricyanide salts, or ferrocene with PolyCo-based electrochromic devices to achieve three oxidation states (Co(I), Co(II), and Co(III), enabling quick switching between black and colorless states, and using carbon nanotubes for enhanced durability in non-aqueous systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a redox-complementary electrochromic device uses only two oxidation states, then the device structure is simple, but the coloring/bleaching contrast is insufficient
Solution Approach 1:
The patent introduces a third oxidation state (Co(III)) in addition to the conventional two states (Co(II) and Co(I)), fundamentally changing the oxidation state parameter from 2 to 3. This enables the electrochromic material to achieve a fully colorless transmissive state when in the Co(III) state, significantly improving the coloring/bleaching contrast beyond what is possible with only two oxidation states.
2Illumination intensity
If PolyCo is used to achieve black-to-transmissive switching, then the transmissive state is achieved, but the state is not fully colorless
Solution Approach 1:
The patent changes the oxidation state parameter of PolyCo from the conventional two-state (Co(II)/Co(I)) to a three-state system (Co(III)/Co(II)/Co(I)). When PolyCo is in the Co(III) state, it exhibits a fully colorless transmissive state, completely resolving the issue of residual coloration that persisted in previous two-state systems.
3Reliability
If an aqueous system is used for the electrochromic device, then the electrochemical reactions proceed, but the system is limited and not suitable for most electrical appliances
Solution Approach 1:
The patent changes the system composition parameter from aqueous to non-aqueous by introducing redox-active materials that function in non-aqueous electrolytes. This enables the electrochromic device to operate in non-aqueous systems while maintaining reliable electrochemical reactions, significantly expanding the adaptability and versatility of the device for various electrical appliance applications.
4Speed
If the electrochromic device switches between black and colorless states rapidly, then the response time is improved, but the mechanical durability may be compromised
Solution Approach 1:
The patent employs composite materials consisting of PolyCo combined with redox-active materials such as ferrocene or ferricyanide. This composite structure enables rapid electron exchange between the different oxidation states, achieving fast switching speeds while the robust composite architecture maintains mechanical durability and structural integrity during repeated cycling.
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 allows for rapid and reversible black-to-transmissive switching with improved mechanical durability and functionality in non-aqueous systems, achieving a fully colorless state and enhanced performance in electrochromic devices.
Implementation Method 1
said redox-active material being capable of reacting with the electrochromic material to change the electrochromic material from black state to colorless transmissive state
Implementation Method 2
an electrochromic Co-based metallo-supramolecular polymer represented by the formula (I)
Data Source
Figure 1(a)~1(c)
Figure 2(a)~2(c)
Figure 3(a)~3(c)
AI summary
Disclosed is a redox-complementary electrochromic device exhibiting black-to-transmissive switching, wherein the device comprises an electrochromic layer and a redox-active material layer sandwiched between a transparent first electrode and a transparent secondary electrode, the electrochromic layer comprising an electrochromic Co-based metallo-supramolecular polymer represented by the formula (I), and the redox active material being capable of reacting with the electrochromic material to change the electrochromic material from black state into colorless transmissive state. (In the formula (I), X represents a counter anion, R represents a single bond or a spacer comprising a carbon atom and a hydrogen atom, each of R1 to R4 independently represents a hydrogen atom or a substituent group, and n represents an integer of from 2 to 5000, which indicates a degree of polymerization.)