Electrochromic Organic Compound Stabilizing Absorption Spectrum
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electrochromic (EC) compounds exhibit significant temperature dependency in their absorption spectra, leading to unstable coloration and low absorbance, which limits their application in full-color displays and other uses.
Innovation Solution
An organic EC compound with a bulky structure composed of three aromatic rings, specifically denoted by general formula [1], is developed, which reduces the formation of associates and maintains the absorption spectrum primarily of monomers, thereby minimizing temperature-dependent changes and enhancing absorbance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional cathodic EC compounds (viologen derivatives) are used, then the device can achieve electrochromic functionality, but the absorption spectrum changes significantly with temperature
Solution Approach 1:
The patent modifies molecular parameters by introducing bulky substituents (tetrafluorophenyl groups) at positions 2 and 6 of the pyridine rings. This structural parameter change increases steric hindrance, preventing associate formation and stabilizing the absorption spectrum against temperature variations.
Solution Approach 2:
The patent creates a composite molecular structure combining a bipyridinium core with bulky aromatic substituents. This composite structure leverages the electrochromic properties of the viologen core while the aromatic substituents provide steric protection against temperature-induced spectral shifts.
2Temperature
If compounds with extended conjugate structures are used to shift absorption wavelength, then the absorption wavelength increases, but the oscillator strength decreases leading to low absorbance
Solution Approach 1:
The patent applies local quality modification by placing electron-withdrawing fluorine atoms at specific positions (2 and 6) of the pyridine rings. This localized substitution enhances the electron deficiency of the pyridine rings, increasing oscillator strength and absorbance without extending the conjugate system.
Solution Approach 2:
The patent changes electronic parameters by introducing fluorine substituents that modify the electron distribution and HOMO-LUMO gap. This parameter change increases the molar extinction coefficient, thereby improving absorbance while maintaining the absorption wavelength in the desired range.
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 compound achieves a stable absorption spectrum with low temperature dependency and high absorbance, suitable for use in electrochromic devices, optical filters, and image pickup apparatuses, providing improved optical density and reduced transmittance.
Implementation Method 1
The electrochromic layer contains an electrochromic compound in which optical absorption properties (coloration state and optical transmittance) of a substance change due to an electrochemical oxidation-reduction reaction
Implementation Method 2
EC materials are required that the light absorption wavelength (form of absorption spectrum) does not change greatly in accordance with the temperature during use
Data Source
AI summary
An organic compound denoted by formula [1],where each of X1 and X2 is independently selected from an alkyl group optionally having a substituent, an aryl group optionally having a substituent, and an aralkyl group optionally having a substituent, each of R11 to R20 is independently selected from a hydrogen atom and a substituent, Y represents an alkyl group optionally having a substituent or an aryl group optionally having a substituent, and each of A1− and A2− independently represents a monovalent anion.