Multi-Sublayer Counter Electrode for Electrochromic Color Stability
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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 color transition, durability, and commercial viability.
Innovation Solution
The development of electrochromic devices with a counter electrode layer comprising multiple sublayers with different compositions and morphologies, including nickel tungsten oxide sublayers with varying concentrations of tantalum, niobium, or tin, which enhance color quality, switching performance, and longevity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-layer counter electrode is used, then the device structure is simple, but the color quality and switching performance are insufficient
Solution Approach 1:
The counter electrode is divided into multiple sublayers (first sublayer, second sublayer, third sublayer) with different compositions and functions. The first sublayer contains nickel tungsten oxide, the second sublayer contains nickel tungsten oxide with additional metals (tantalum, niobium, or tin), and the third sublayer contains nickel tungsten oxide, creating a segmented structure that improves color quality and switching performance while maintaining reasonable device complexity
Solution Approach 2:
Different sublayers are designed with specific local compositions optimized for their positions: the first sublayer provides baseline electrochromic performance, the second sublayer with added metals enhances color quality and stability, and the third sublayer provides additional functional benefits. This local quality differentiation resolves the contradiction by improving performance where needed without unnecessarily complicating the entire structure
2Reliability
If the counter electrode uses complex multi-sublayer composition, then color quality and lifespan are improved, but manufacturing complexity increases
Solution Approach 1:
The patent systematically varies compositional parameters (metal ratios, additional metal concentrations) and deposition parameters (thickness of each sublayer, deposition conditions) to optimize performance. By controlling these parameters during fabrication, the patent achieves improved color quality and lifespan while maintaining a manufacturing process that, though multi-step, follows established electrochromic device fabrication methodologies
Solution Approach 2:
The counter electrode employs composite materials strategy by combining nickel tungsten oxide with additional metals (tantalum, niobium, or tin) in specific sublayers. This composite approach improves device reliability and color quality while using materials and deposition techniques that are compatible with existing manufacturing capabilities, thus balancing performance improvement with manufacturing feasibility
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 achieves improved color quality, extended lifespan, and efficient switching performance by optimizing the composition and morphology of the counter electrode layer, leading to more reliable and effective electrochromic devices.
Implementation Method 1
a counter electrode layer also disposed on or over the substrate, the counter electrode layer including (a) a first sublayer including a first anodically tinting material, and (b) a second sublayer including a second anodically tinting material
Implementation Method 2
The optical property is typically one or more of color, transmittance, absorbance, and reflectance. One well known electrochromic material, for example, is tungsten oxide (WO3). Tungsten oxide is a cathodic electrochromic material in which a coloration transition, transparent to blue, occurs by electrochemical reduction.
Implementation Method 3
The gradient (if present) is typically in a direction that is normal to the plane of the counter electrode. In various embodiments, the composition is heterogeneous with respect to the concentration of one or more metals in the counter electrode material.
Implementation Method 4
the first and second anodically tinting materials have different compositions but each include an oxide of at least one transition metal
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.