Multi-layer polymeric cathode for high contrast electrochromic devices
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Solution Overview
Problem
Existing electrochromic devices face challenges in achieving commercially acceptable levels of contrast and aesthetic appearance, particularly when using inorganic electrodes, which can limit their functionality in applications such as architectural windows and vehicle transparencies.
Innovation Solution
The use of a multi-layer polymeric cathode comprising two cathodically coloring polymers with an ionic liquid positioned between the polymeric anode and cathode, where the first polymer provides excellent adhesion and the second polymer enhances contrast and film smoothness, improving the device's performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-layer polymeric cathode is used, then the device structure is simpler, but the contrast and aesthetic appearance are insufficient
Solution Approach 1:
The cathode is divided into multiple layers, each with specific functions: the first layer (polymer matrix) provides adhesion and structural support, while the second layer (conjugated polymer) provides the electrochromic contrast function. This segmentation allows each layer to be optimized independently, achieving high contrast without excessive overall complexity.
Solution Approach 2:
The multi-layer cathode uses composite material structure where different polymeric materials are combined: a polymer matrix material for structural integrity and adhesion, combined with an electrochromic conjugated polymer material for optical contrast. This composite approach achieves properties that neither material could provide alone.
2Device complexity
If the second polymer is applied directly onto the substrate, then the structure is simpler, but the film smoothness and contrast are reduced
Solution Approach 1:
The first polymer layer acts as an intermediary between the substrate and the second electrochromic polymer layer. This intermediate layer provides a controlled surface that enables the second polymer to form a smooth, uniform film with better adhesion, achieving manufacturing precision that would be difficult to obtain by direct deposition onto the substrate.
Solution Approach 2:
The first polymer layer is deposited first to prepare the surface in advance. This preliminary action creates an optimal substrate surface for subsequent polymer deposition, ensuring smooth film formation and good adhesion before the functional electrochromic layer is applied.
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 configuration enhances the contrast and aesthetic appearance of electrochromic devices, offering improved functionality and performance compared to conventional devices, particularly in applications requiring high visibility and transparency.
Implementation Method 1
electrochromic materials that change color in a reversible manner as a result of the application of an electrical potential
Implementation Method 2
An ionic liquid is position between the polymeric anode and polymeric cathode
Data Source
AI summary
An electrochromic device includes a first substrate spaced from a second substrate. A first transparent conductive electrode is formed over at least a portion of the first substrate. A polymeric anode is formed over at least a portion of the first conductive electrode. A second transparent conductive electrode is formed over at least a portion of the second substrate. In one aspect of the invention, a multi-layer polymeric cathode is formed over at least a portion of the second conductive electrode. In one non-limiting embodiment, the multi-layer cathode includes a first cathodically coloring polymer formed over at least a portion of the second conductive electrode and a second cathodically coloring polymer formed over at least a portion of the first cathodically coloring polymer. An ionic liquid is positioned between the anode and the cathode.