Heterogeneous Counter Electrode Layers for Electrochromic Switching
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Solution Overview
Problem
Electrochromic devices have historically faced challenges in realizing their full commercial potential due to various issues, including inefficient optical property changes and limited commercial applications.
Innovation Solution
The development of electrochromic devices with a counter electrode layer comprising multiple sublayers with different compositions and morphologies, including a gradient in composition normal to the plane, enhances optical property changes and device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single-layer counter electrode is used, then the device structure is simple, but the optical property changes are inefficient and visual properties are poor
Solution Approach 1:
The counter electrode is divided into multiple sublayers (first sublayer, second sublayer, and third sublayer) with different compositions and functions. The first sublayer contains nickel oxide and tungsten oxide, the second sublayer contains nickel oxide, tungsten oxide, and aluminum oxide, and the third sublayer contains nickel oxide and tungsten oxide. This segmentation allows each sublayer to contribute differently to the overall optical property changes, improving efficiency while maintaining a manageable structure.
Solution Approach 2:
The patent employs composite materials in the counter electrode sublayers, combining multiple metal oxides (nickel oxide, tungsten oxide, aluminum oxide) in specific ratios. This composite approach enables synergistic effects that enhance optical property changes beyond what single materials can achieve, addressing the inefficiency of simple single-layer structures.
2Reliability
If a heterogeneous composition with gradient is implemented, then visual properties and switching behavior improve, but the manufacturing process becomes more complex
Solution Approach 1:
Different sublayers are assigned specific compositions tailored to their local functions. The first sublayer has a composition optimized for initial electrochromic response, the second sublayer includes aluminum oxide for enhanced stability and intermediate states, and the third sublayer is optimized for final state achievement. This local quality approach improves switching behavior while keeping each sublayer's composition manageable.
Solution Approach 2:
The patent systematically varies compositional parameters (metal oxide ratios, presence of aluminum oxide) across different sublayers to optimize switching behavior. By controlling parameters like the ratio of nickel oxide to tungsten oxide and introducing aluminum oxide in the second sublayer, the patent achieves improved reliability without requiring complete redesign of the entire electrode.
3Illumination intensity
If multiple sublayers with different compositions are deposited, then the transmitted b* value and visible transmittance improve, but the number of deposition steps increases
Solution Approach 1:
The counter electrode is segmented into three depositable sublayers with distinct compositions. The first sublayer (nickel oxide and tungsten oxide) establishes baseline optical properties, the second sublayer (nickel oxide, tungsten oxide, and aluminum oxide) enhances transmittance and controls color, and the third sublayer (nickel oxide and tungsten oxide) fine-tunes the final optical state. This segmentation achieves the required transmitted b* value of 14 or lower and visible transmittance of at least 55% through coordinated layer contributions.
Solution Approach 2:
The use of composite materials, particularly the inclusion of aluminum oxide in the second sublayer alongside nickel oxide and tungsten oxide, enables enhanced visible transmittance and controlled coloration. This composite approach achieves superior optical properties compared to single-material layers, with each composite layer contributing to the overall transmittance and color performance.
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 approach improves the visual properties and switching behavior of electrochromic devices, achieving a clear state with a transmitted b* value of 14 or lower and visible transmittance of at least 55%, while maintaining long-term reliability and efficiency.
Implementation Method 1
Electrochromism is a phenomenon in which a material exhibits a reversible electrochemically-mediated change in an optical property when placed in a different electronic state, typically by being subjected to a voltage change. The optical property is typically one or more of color, transmittance, absorbance, and reflectance.
Data Source
AI summary
The embodiments herein relate to electrochromic stacks, electrochromic devices, and methods and apparatus for making such stacks and devices. In various embodiments, an anodically coloring layer in an electrochromic stack or device is fabricated to include a heterogeneous structure, for example a heterogeneous composition and/or morphology. Such heterogeneous anodically coloring layers can be used to better tune the properties of a device.