Meta-Conjugated Electrochromic Polymers for High Transparency
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Solution Overview
Problem
Conventional conjugated electrochromic polymers have strong absorbance in the visible light region in their neutral state, leading to coloration, and when oxidized, they shift absorption to the near-infrared region, resulting in weak visible light absorption and limited optical contrast, which impairs their ability to manage solar heat gain effectively.
Innovation Solution
The development of electrochromic polymers with meta-conjugated linkers and aromatic moieties, which are partially conjugated at meta positions, allowing for high transparency in the neutral state and significant absorption in the visible and near-infrared regions upon oxidation, thereby enhancing optical contrast and solar heat management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional conjugated electrochromic polymers are used, then they provide electrochromic functionality, but they exhibit strong absorbance in the visible light region in the neutral state leading to coloration and limited optical contrast
Solution Approach 1:
The patent applies parameter changes by modifying the chemical structure of the polymer backbone, specifically introducing meta-conjugated linkers between aromatic moieties. This structural parameter change alters the electronic conjugation pattern, which shifts the absorption spectrum to achieve high transparency in the neutral state while maintaining strong absorption in the oxidized state, thereby resolving the contradiction between electrochromic functionality and optical contrast
Solution Approach 2:
The patent employs composite material design by creating a polymer with alternating aromatic moieties and meta-conjugated linkers. This composite structure combines the optical properties of aromatic units (which provide coloration upon oxidation) with the transparency-enhancing properties of meta-conjugated linkers, achieving both high optical contrast and effective solar heat gain control
2Illumination intensity
If the polymer films are made thick to enhance absorption, then the optical contrast improves, but the residue colors become more severe and the highest optical transmittance is limited
Solution Approach 1:
The patent changes the conjugation parameter of the polymer backbone by introducing meta-linkers, which fundamentally alters how absorption scales with thickness. Unlike conventional polymers where increased thickness amplifies both desired absorption and unwanted residue colors, the meta-conjugated structure ensures that thickness enhancement primarily improves optical contrast while maintaining high transmittance in the neutral state
3Temperature
If conventional ECPs are used, then they allow visible light passing through in the transmissive state, but they block near-IR light which is not effective for thermal management and control the solar-heat gain
Solution Approach 1:
The patent changes the absorption spectrum parameters of the polymer by implementing meta-conjugated linkers, which shifts the absorption characteristics to enable simultaneous control of both visible and near-infrared regions. This parameter modification allows the polymer to block near-IR light in the transmissive state while maintaining visible light transmission, achieving effective thermal management and solar heat gain control
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
These polymers achieve high optical contrast and transmittance, enabling effective solar heat management by being transparent in the neutral state and colored in the oxidized state, with the ability to tune color and maintain stability across multiple switching cycles.
Implementation Method 1
the electrochromic layer has transmittance of 40%-0.1% at a wavelength of 550 nm at an oxidized state of the electrochromic layer
Implementation Method 2
an electrochromic layer disposed over the first conducting layer, wherein the electrochromic layer comprises an electrochromic polymer
Data Source
AI summary
An electrochromic device includes: a first insulating substrate; a first conducting layer disposed over the first insulating substrate; an electrochromic layer disposed over the first conducting layer, wherein the electrochromic layer comprises an electrochromic polymer having a polymer backbone comprising one or more meta-conjugated linkers (MCLs) and one or more aromatic moieties (Ars), wherein each of the one or more MCLs is partially conjugated with one of the one or more Ars at a meta position of the one or more MCLs; an electrolyte layer disposed over the electrochromic layer; a second conducting layer disposed over the electrolyte layer; and a second insulating substrate disposed over the second conducting layer. A thickness of the electrochromic layer is from 10 nm to 1500 nm resulting in transmittance of 85%-99.9% at a wavelength of 550 nm at a neutral state of the electrochromic layer.