Nanostructured Electrochromic Films for Low-Voltage Operation
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Solution Overview
Problem
Current electro-chromic film stacks are not compact, mechanically robust, and require high voltages, making them unsuitable for applications like ophthalmic lenses and large-area transparent surfaces, and they have slow response times and limited dynamic range.
Innovation Solution
A method involving the deposition of nanostructured electro-chromic layers using materials like tungsten oxide, nickel oxide, or their combinations, at controlled incident angles, with ion-conducting layers and electrodes, to create fast-responding, high-color-efficiency electro-chromic film stacks that can be applied to various surfaces, including ophthalmic lenses and architectural windows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional electro-chromic film stacks are used, then they can change optical transmission properties, but they require high voltages and large batteries, making them non-compact and mechanically non-robust
Solution Approach 1:
The patent changes the material parameters by using tungsten oxide nanostructures with controlled crystallographic orientations (specifically <001> orientation) to achieve electro-chromic switching at lower voltages. The nanostructured morphology and crystal orientation are optimized to reduce the energy barrier for ion insertion/extraction, enabling operation at lower voltages while maintaining mechanical robustness through solid-state construction.
Solution Approach 2:
The patent employs composite material structures combining tungsten oxide nanostructures with ion-conducting layers and electrode materials. This composite approach creates a mechanically robust solid-state device where each component contributes specific properties: tungsten oxide provides electro-chromic functionality, ion-conducting layers enable ion transport, and electrodes provide electrical connectivity, collectively achieving low-voltage operation and mechanical durability.
2Speed
If conventional electro-chromic film stacks are used, then they can provide variable transmission, but they have slow response times and limited dynamic range
Solution Approach 1:
The patent utilizes porous tungsten oxide nanostructures with high surface area to volume ratios. The porous morphology provides numerous active sites for rapid ion insertion and extraction, significantly accelerating the electro-chromic response time. The nanoscale pore dimensions facilitate fast ion diffusion pathways, enabling rapid switching between transparent and colored states while expanding the dynamic range of transmission control.
Solution Approach 2:
The patent transitions from bulk electro-chromic materials to nanoscale structures, effectively moving the functionality to a different dimensional regime. This dimensional reduction creates shorter ion transport pathways and increases the surface area available for electrochemical reactions, thereby dramatically improving response speed and expanding the achievable dynamic range of optical modulation.
3Object-affected harmful factors
If electro-chromic film stacks are applied to ophthalmic lens blanks, then they can reduce UV transmission, but they must survive post-processing steps like surfacing, edging, and grooving
Solution Approach 1:
The patent employs thin film electro-chromic structures that can be conformally deposited on curved lens surfaces. These thin films are mechanically flexible and adherent, allowing them to withstand the mechanical stresses of post-processing operations such as surfacing, edging, and grooving without delamination or fracture, while maintaining their UV blocking and electro-chromic functionalities.
Solution Approach 2:
The patent integrates the electro-chromic functional layer directly with the lens substrate through conformal deposition, merging the optical correction function of the lens with the electro-chromic modulation function. This integrated structure ensures that the electro-chromic layer moves and deforms with the lens during post-processing, maintaining structural integrity and functional performance throughout manufacturing operations.
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 resulting film stacks exhibit improved coloration efficiency and faster response times under lower voltages, surviving post-processing steps and offering controllable variable transmission properties, suitable for energy-saving applications.
Implementation Method 1
depositing an electro-chromic material over a surface having a surface normal to form a nanostructured electro-chromic layer over an optical substrate by exposing the surface to a flux of the electro-chromic material traveling in a first direction; wherein an incident angle between the first direction and the surface normal is at least 1 degree and at most 89 degrees
Implementation Method 2
The EC film stack should also survive all post-processing steps of the surfaces that it is applied to... The article 'Angular selective transmittance through electrochromic tungsten oxide films made by oblique angle scattering', written by D. Le Bellac and published in Appl. Phys. Lett. 66 (14), pages 1715 and 1716 relates to tungsten oxide films which are formed by magnetron sputtering
Implementation Method 3
When a voltage is applied, ions and electrons are transferred between the different layers, resulting in a change of the optical properties of the stack. When the voltage is turned off, the stack's optical properties return to the unaltered state
Implementation Method 4
An electro-chromic (EC) film stack generally comprises at least one electro-chromic layer in contact with at least one ion conductor layer
Data Source
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AI summary
EC film stacks and different layers within the EC film stacks are disclosed. Methods of manufacturing these layers are also disclosed. In one embodiment, an EC layer comprises nanostructured EC layer. These layers may be manufactured by various methods, including, including, but not limited to glancing angle deposition, oblique angle deposition, electrophoresis, electrolyte deposition, and atomic layer deposition. The nanostructured EC layers have a high specific surface area, improved response times, and higher color efficiency.