Non-electrolytic Deposition for Electrochromic Coatings
Solution Overview
Problem
Existing electrochromic device deposition methods face challenges in achieving homogeneous deposits on large areas due to the complexity of adapting electrodeposition devices and the high square resistance of conductive layers, leading to irregular thickness and difficulty in depositing electrochromic compounds on non-conductive substrates.
Innovation Solution
A non-electrolytic deposition process involving the deposition of a redox agent on a limited area of a conductive layer, followed by contact with a precursor solution, allowing an indirect redox reaction to form an insoluble electrochromic compound, ensuring electroneutrality and facilitating uniform deposition across large areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If electrodeposition is used to deposit electrochromic compounds on large substrates, then deposition can be achieved, but the device complexity increases and homogeneous deposits cannot be obtained due to high square resistance of ITO films
Solution Approach 1:
The patent extracts the redox reaction function from the electrodeposition system by removing the need for complex electrode connections and power supplies. Instead of using electrolytic reduction, the invention employs chemical redox agents (such as ascorbic acid or hydroquinone) deposited on the ITO surface to directly reduce the electrochromic precursor, eliminating the need for complex electrodeposition device geometry adaptations.
Solution Approach 2:
The patent introduces a redox agent as an intermediary substance between the electrochromic precursor and the ITO conductive layer. The redox agent (e.g., ascorbic acid, hydroquinone) serves as a chemical mediator that transfers electrons to the precursor through direct contact on the ITO surface, replacing the need for external electrical connections and complex electrodeposition apparatus.
2Adaptability or versatility
If ITO films with high square resistance (at least 60 ohm/square) are used on plastic substrates, then flexible substrates can be used, but the thickness of electrochromic deposit decreases with distance from the electrode connection point
Solution Approach 1:
The patent enables the ITO conductive layer to serve itself by depositing redox agents directly onto its surface. The redox agents then utilize the ITO's own electrical conductivity to facilitate the reduction reaction in situ, eliminating the need for external electrode connections. This self-service approach ensures uniform deposit thickness across the entire substrate surface regardless of distance from any connection point.
Solution Approach 2:
The patent changes the deposition mechanism from electrolytic to chemical redox, fundamentally altering the reaction parameters. By using chemical redox agents with appropriate reduction potentials (such as ascorbic acid or hydroquinone), the deposition process becomes independent of electrical resistance variations across the ITO film, enabling uniform deposits on flexible substrates with high square resistance.
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 process enables the deposition of electrochromic compounds with regular thickness and uniformity on large areas, overcoming the limitations of traditional electrodeposition methods, and is applicable to both conductive and non-conductive substrates, reducing material losses and simplifying the deposition process.
Implementation Method 1
an indirect redox reaction takes place, via the conductive layer, between the redox agent deposited thereon and the precursor in the solution. The precursor in solution, coming into contact with the surface of the conductive layer, is reduced or oxidized and forms an insoluble compound which is deposited on the surface of the conductive layer. During this oxidation-reduction reaction involving the redox agent (reducing or oxidizing) and the precursor in the solution, the exchange of electrons takes place indirectly via the electrically conductive layer.
Data Source
AI summary
The invention relates to a method for the non-electrolytic deposition of a compound, preferably an electrochromic compound, comprising the following successive steps: (a) an electroconductive layer is deposited on a non-conductive solid substrate; (b) a reducing agent or an oxidizing agent(= redox agent) is deposited on an area of said electroconductive layer, said area covering only a portion of the surface of said electroconductive layer; and (c) a solution of a precursor of the compound to be deposited is brought into contact both with the redox agent and with at least a portion of the area of said electroconductive layer not covered by the redox agent, said precursor being chosen from those having an oxidation-reduction potential higher or lower than the redox agent and forming, after an oxidation-reduction reaction, a compound insoluble in the solution of the precursor of the compound to be deposited.