Electrochromic Layer Oxidizable Substance Charge Balance
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Solution Overview
Problem
Electrochromic devices with organic compounds face issues of residual coloring and changes in absorption spectrum due to charge imbalance, which affect transparency and desired optical properties, as existing solutions like redox buffers cannot fully correct the ratio of anodic and cathodic compounds in a colored state.
Innovation Solution
Incorporating an oxidizable substance and a reducible substance into the electrochromic layer that do not undergo significant color change during oxidation or reduction reactions, allowing for controlled charge balance and reversible reactions to maintain desired absorption spectra.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a redox buffer is used to suppress residual coloring, then transparency in decolored state is improved, but charge imbalance between electrodes cannot be eliminated and absorption spectrum in colored state changes
Solution Approach 1:
The patent introduces an oxidizable substance as an intermediary material that mediates charge balance between the anodic EC compound and cathode. This substance undergoes oxidation to generate oxidants that decolor the anodic EC compound, thereby suppressing residual coloring while maintaining charge balance without disrupting the absorption spectrum of the cathodic EC compound.
Solution Approach 2:
The patent changes the chemical parameters by selecting specific oxidizable substances with appropriate oxidation potentials and kinetics. By controlling the oxidation reaction parameters and the resulting oxidant characteristics, the system achieves complete decoloration while preventing unwanted changes in the absorption spectrum of the colored state.
2Adaptability or versatility
If organic EC compounds are used to achieve both transparency and high absorbance, then optical properties are improved, but charge imbalance occurs due to deterioration of the EC compound
Solution Approach 1:
The oxidizable substance serves as a mediator that transfers charge between electrodes through controlled oxidation. This intermediary mechanism protects the organic EC compounds from direct deterioration while maintaining charge balance, allowing the system to achieve both wide optical property range and long-term reliability.
Solution Approach 2:
The oxidizable substance automatically undergoes oxidation when charge imbalance occurs, generating oxidants that self-correct the charge imbalance by decoloring the anodic EC compound. This self-service mechanism maintains charge balance without external intervention, improving reliability while preserving the optical versatility of organic EC compounds.
3Reliability
If the oxidizable substance undergoes oxidation to correct charge imbalance, then residual coloring is suppressed, but the substance itself may be consumed
Solution Approach 1:
The patent designs the oxidizable substance to be sacrificial, intentionally allowing its consumption during charge rebalance. The substance is discarded (consumed) in controlled amounts to correct charge imbalance, while the main EC compounds are recovered and reused for multiple coloring-decoloring cycles, improving overall device reliability.
Solution Approach 2:
The oxidizable substance is present in excess relative to the amount needed for normal operation, allowing it to partially consume itself during charge imbalance correction. This excessive action ensures complete decoloration and charge balance restoration without limiting the operational lifetime of the main EC compounds.
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 approach effectively suppresses residual coloring and changes in absorption spectrum, ensuring consistent transparency and optical properties by rebalancing charges through irreversible reactions of the oxidizable or reducible substances, improving the stability and performance of electrochromic devices.
Implementation Method 1
the electrochromic layer contains an anodic electrochromic compound and an oxidizable substance
Implementation Method 2
EC devices that use such an EC compound are applied to, for example, display apparatuses, variable-reflectivity mirrors, and variable transmission windows
Implementation Method 3
the electrochromic layer contains a cathodic electrochromic compound and a reducible substance
Implementation Method 4
EC devices that use such an EC compound are applied to, for example, display apparatuses, variable-reflectivity mirrors, and variable transmission windows
Implementation Method 5
an oxidation reaction of the oxidizable substance is less likely to occur than an oxidation reaction of the anodic electrochromic compound
Implementation Method 6
a reduction reaction of the reducible substance is less likely to occur than a reversible reduction reaction of the cathodic electrochromic compound
Data Source
AI summary
An electrochromic device according to the present disclosure includes an electrochromic element that includes a first electrode, a second electrode, and an electrochromic layer disposed between the first electrode and the second electrode. The electrochromic layer contains an anodic electrochromic compound and an oxidizable substance. The oxidizable substance is a substance which substantially does not undergo a color change due to oxidation and whose oxidant is not reduced. An oxidation reaction of the oxidizable substance is less likely to occur than an oxidation reaction of the anodic electrochromic compound. A controller is configured to control oxidation of the oxidizable substance based on a charge balance of the electrochromic element.