Electrochromic Film Passivation Layer for Smart Windows
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Solution Overview
Problem
Electrochromic devices suffer from slow color-switching speed and durability issues, particularly when used in large areas or with high sheet resistance transparent conductive electrodes, limiting their application in smart windows and other architectural materials.
Innovation Solution
An electrochromic film comprising an electrochromic layer and a passivation layer with specific light transmission characteristics, where the passivation layer is made of a metal oxynitride with controlled elemental content ratios and thickness, enhancing adhesion, durability, and light transmittance, and having a different coloration level than the electrochromic layer to improve color-switching speed and optical adjustment capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the transparent conductive electrode has high sheet resistance or the electrochromic device is required to have a large area, then the device can be manufactured with lower cost or larger scale, but the color-switching speed becomes significantly slower
Solution Approach 1:
The patent divides the electrochromic layer into multiple sub-layers, each containing electrochromic material. This segmentation allows for better distribution of electrochemical reactions across the layer, improving the overall color-switching speed by reducing the diffusion distance for electrolyte ions and electrons within each sub-layer.
Solution Approach 2:
The patent applies different materials and structures to different parts of the electrochromic device. Specifically, the transparent conductive electrode is designed with a specific sheet resistance range (10-100 Ω/□) and the electrochromic layer has specific thickness and material composition variations to optimize local electrochemical performance, thereby improving color-switching speed without compromising overall device reliability.
2Area of stationary object
If the electrochromic device is designed for large area application, then it can be used for smart windows and architectural materials, but the time required for electrolyte ion insertion and removal across the entire area increases
Solution Approach 1:
The electrochromic layer is segmented into multiple sub-layers, which reduces the effective diffusion path length for electrolyte ions across the entire device area. This allows large-area devices to achieve faster color-switching times by processing the electrochemical reaction in parallel across multiple thinner sub-layers rather than through a single thick layer.
Solution Approach 2:
The patent introduces a vertical dimension to the electrochromic layer structure by creating multiple sub-layers stacked in the thickness direction. This dimensional transformation allows the device to maintain large horizontal area while reducing the vertical ion transport distance, thereby decoupling device area from color-switching time.
3Duration of action of stationary object
If the electrochromic material undergoes repeated electrochemical cycling, then the device can be used durably, but the durability and usable level deteriorate over time
Solution Approach 1:
The patent incorporates a protective structure and optimizes the electrochromic layer composition beforehand to cushion against degradation during cycling. The specific material composition and layer structure are designed in advance to resist mechanical stress, chemical degradation, and ion insertion/removal stresses, thereby maintaining durability and usable level over repeated cycling operations.
Solution Approach 2:
The electrochromic layer is designed as a composite structure with specific material compositions and multi-layer configuration. This composite approach combines materials with complementary properties to enhance both durability and optical performance, allowing the device to maintain high usable level even after repeated electrochemical cycling.
4Reliability
If the passivation layer is added to improve adhesion and durability, then the device reliability improves, but the light transmission characteristics may be compromised
Solution Approach 1:
The passivation layer is designed with specific parameter optimizations including controlled thickness (within a specific range to balance protection and transparency), specific material composition, and specific structural characteristics. These parameter changes allow the passivation layer to provide adequate adhesion and durability protection while maintaining sufficient light transmission characteristics for the electrochromic device to function effectively.
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 electrochromic film and device exhibit improved electrochromism rate, durability, and the ability to finely adjust optical properties, achieving faster color-switching and maintaining high transmittance, even under repeated cycling, thus addressing the limitations of existing technologies.
Implementation Method 1
Electrochromism refers to a phenomenon in which an optical property of an electrochromic material is changed by an electrochemical oxidation or reduction reaction
Implementation Method 2
an optical property of an electrochromic material is changed by an electrochemical oxidation or reduction reaction
Implementation Method 3
as the electrolyte ions are inserted into or removed from the electrochromic material-containing film
Implementation Method 4
the electrons simultaneously move through an external circuit
Data Source
AI summary
An electrochromic film and an electrochromic device including the electrochromic film are disclosed. The electrochromic film includes an electrochromic layer and a passivation layer on one side of the electrochromic layer. The coloration level of the electrochromic film is different from the coloration level of the passivation layer. The film may change optical properties as a result of electrochromism according to an electrochemical reaction. The electrochromic film and the electrochromic device have improved electrochromism, excellent durability, excellent color-switching speed, and stepwise control of optical properties.