Photochromic-Electrochromic Composition for Low-Power Optical Filters
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Solution Overview
Problem
Photochromic-electrochromic materials that are dark in their inactive state require continuous electricity to maintain the clear or faded state, leading to energy inefficiencies and potential degradation due to uncontrolled oxidation or reduction processes.
Innovation Solution
Incorporating a partner cathodic species in the composition to balance redox chemistry, allowing for less stoichiometric charge injection and minimizing material degradation, while maintaining the dark or faded state without interfering with the transition process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If photochromic-electrochromic materials are designed to be dark in their inactive state to reduce solar heat gain, then energy savings from reduced solar heat gain are achieved, but continuous application of electricity is required to maintain the dark state which drains the battery
Solution Approach 1:
The patent inverts the conventional electrochromic behavior by designing a system where the inactive state is dark (colored) and the active state is clear. This is achieved by using a photochromic compound that darkens upon UV exposure and an electrochromic compound that clears upon voltage application. The system naturally returns to the dark state when power is removed, eliminating the need for continuous power to maintain the dark state while still providing solar heat reduction benefits.
Solution Approach 2:
The photochromic component serves itself by automatically darkening in response to UV light from sunlight without requiring external control. When the electrochromic component is deactivated, the photochromic compound naturally returns to its dark state, providing self-regulating solar heat rejection without continuous power consumption.
2Ease of operation
If electrochemical oxidation is used to transition the material to a clear state, then the switching function is achieved, but degradation of the switchable material occurs due to uncontrolled oxidation or reduction processes
Solution Approach 1:
The patent introduces an ionic liquid electrolyte as an intermediary medium that facilitates controlled ion transport between the electrodes and the chromogenic compounds. The ionic liquid provides a stable, non-volatile environment that enables precise electrochemical control of the clearing process while protecting the photochromic and electrochromic compounds from degradation. The electrolyte acts as a buffer that mediates the redox reactions, preventing uncontrolled oxidation or reduction that would otherwise degrade the materials.
Solution Approach 2:
The patent utilizes changes in electrochemical parameters (voltage, current, electrolyte composition) to control the oxidation and reduction processes. By carefully selecting the electrochromic compound and electrolyte parameters, the system achieves reversible switching with minimal degradation. The ionic liquid electrolyte allows for controlled potential sweeps that prevent excessive oxidation or reduction beyond the stable ranges of the chromogenic 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
The solution enhances the durability, cycling time, and UV resistance of the switchable material by reducing the need for continuous electricity and minimizing degradation, thereby improving the overall performance and longevity of the material.
Implementation Method 1
oxidation of these compounds electrocatalytically transitions the material to a clear or faded state
Implementation Method 2
Photochromic-electrochromic compositions
Implementation Method 3
Initiation of electrochemical oxidation of a species at the anode necessitates a partner electrochemical reduction at the cathode
Implementation Method 4
chromogenic compounds or switching materials with a photo-responsive aspect
Data Source
AI summary
A composition comprising a diarylethene photochromic anodic species, a cathodic species and an electrolyte that comprises a supporting electrolyte and a solvent. Electrochromic devices such as optical filters are prepared from such compositions.