Electrochromic Device Residual Coloring Suppression
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Solution Overview
Problem
Low-molecular-weight organic electrochromic devices face issues with anodic charge imbalance-induced residual coloring, leading to incomplete decoloring and increased power consumption due to the use of redox buffers that are more easily oxidized than anodic EC compounds, affecting transmittance and response time.
Innovation Solution
Incorporating multiple anodic electrochromic compounds and a cathodic redox substance in the electrochromic device, with specific ratios and indices such as RGmax, RΔOD, and RWΔOD, to suppress anodic charge imbalance-induced residual coloring without increasing power consumption or deteriorating response time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a redox buffer that is more easily oxidized than anodic EC compounds is used to suppress charge imbalance, then residual coloring is reduced, but power consumption increases and response time deteriorates
Solution Approach 1:
The patent changes the chemical parameters of the redox buffer by specifying its oxidation potential must be higher than the anodic EC compound's oxidation potential. This parameter adjustment ensures the buffer reacts after the EC compound during coloring, preventing residual coloring without causing excessive current flow or power consumption increase.
Solution Approach 2:
The patent creates a composite electrochromic system combining multiple components: anodic EC compounds, cathodic EC compounds, and a redox buffer with specifically controlled oxidation potential. This composite structure enables the buffer to suppress charge imbalance effects while maintaining normal coloring performance and power consumption characteristics.
2Reliability
If a redox buffer that is more easily oxidized than anodic EC compounds is used to suppress charge imbalance, then residual coloring is reduced, but response time deteriorates
Solution Approach 1:
The patent adjusts the oxidation potential parameter of the redox buffer to be higher than that of the anodic EC compound. This ensures the buffer operates at a different electrochemical potential, reacting after the EC compound during coloring transitions, thus maintaining fast response time while suppressing residual coloring from charge imbalance.
Solution Approach 2:
The redox buffer acts as an intermediary substance that mediates charge imbalance without interfering with the primary coloring reaction. By having a higher oxidation potential than the anodic EC compound, it serves as a secondary reaction pathway that only activates when needed to balance charges, preserving the main coloring response time.
3Reliability
If multiple anodic EC compounds with specific absorption characteristics are used, then residual coloring is suppressed and transmittance control is improved, but device complexity increases
Solution Approach 1:
The patent employs a composite approach by combining multiple anodic EC compounds with different absorption characteristics in the electrochromic layer. This composite material strategy enables broader spectral control and better suppression of residual coloring while maintaining a relatively simple device structure through material-level complexity rather than structural complexity.
Solution Approach 2:
The multiple anodic EC compounds serve multiple functions simultaneously: they provide broad-spectrum light absorption control, enable precise transmittance adjustment across different wavelengths, and collectively suppress residual coloring through their complementary absorption characteristics. This multi-functionality reduces the need for additional separate components.
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 effectively reduces residual coloring and maintains optimal transmittance control, extending the usable time of the electrochromic device by ensuring the colored state of anodic EC compounds is closer to an achromatic color, thereby minimizing the influence of charge imbalances on optical characteristics.
Implementation Method 1
low-molecular-weight organic EC compounds in which the optical characteristics (absorption wavelength and absorbance) of their materials change through electrochemical redox reactions
Implementation Method 2
the maximum value of the ratio between the variable optical densities at specific wavelengths in the spectra of the colored forms of the multiple anodic EC compounds and the reduction reaction potential of the cathodic redox substance
Data Source
AI summary
The types and concentrations of multiple anodic electrochromic compounds are selected in such a manner that RGmax is 1.37 or less, in which RGmax is a maximum value among ratios between RGB signal ratios in the transmission state of an electrochromic device and in colored states of the anodic electrochromic compounds, the RGB signal ratios are obtained from TA(λ) and the sensitivity of a photodetector, and TA(λ) is a normalized variable transmittance obtained by a combination of absorptions of the anodic electrochromic compounds.