Meta-Conjugated Electrochromic Polymers for Residual Color Control
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Solution Overview
Problem
Conventional conjugated electrochromic polymers (ECPs) exhibit strong absorbance in the visible light region in their neutral state, leading to residual colors and limited optical contrast, which affects their ability to manage solar-heat gain effectively.
Innovation Solution
The development of electrochromic polymers with meta-conjugated linkers and aromatic moieties that are transparent in the neutral state and absorb in the visible and near-infrared regions upon oxidation, achieving high optical contrast and transmittance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional conjugated electrochromic polymers are used, then the polymer structure provides electrochromic functionality, but the polymer exhibits strong absorbance in the visible light region in the neutral state leading to residual colors and limited optical contrast
Solution Approach 1:
The polymer structure is segmented into distinct functional units: meta-conjugated linker units (MCL) and aromatic moiety units (Ac). This segmentation allows the neutral state to have interrupted conjugation (high transparency) while the oxidized state enables charge delocalization across these segments (colored state), achieving high optical contrast without residual colors
Solution Approach 2:
The patent changes the conjugation parameter by using meta-conjugated linkers instead of fully conjugated structures. This parameter change results in interrupted conjugation in the neutral state (transparent) versus delocalized conjugation in the oxidized state (colored), eliminating residual colors and achieving superior optical contrast
2Illumination intensity
If the polymer films are made thick to enhance coloring, then the absorption in the colored state increases, but the residue colors become more severe and optical contrast is negatively impacted
Solution Approach 1:
The segmented structure with meta-conjugated linkers ensures that even in thick films, the neutral state maintains interrupted conjugation throughout, preventing residual color accumulation. The colored state achieves strong absorption through oxidized charge delocalization across the segmented units, maintaining high optical contrast regardless of film thickness
3Adaptability or versatility
If conventional ECPs are used, then the neutral state blocks visible light and allows near-IR light passing through, but this combination is not effective for thermal management and control the solar-heat gain
Solution Approach 1:
The meta-conjugated electrochromic polymer achieves multi-functionality by simultaneously controlling both visible and near-infrared light transmission in the colored state. This universal light blocking capability enables effective thermal management and solar-heat gain control, unlike conventional ECPs that only control visible light
Solution Approach 2:
The patent changes the optical properties parameter by achieving broad-spectrum absorption (visible and near-IR) in the oxidized state through the meta-conjugated structure. This parameter change enables the polymer to function as both an optical modulator and a thermal management material, improving energy efficiency
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 new polymers enable synchronized control of visible and near-IR light transmission, enhancing optical contrast and transmittance, and improving thermal management through better solar-heat gain control.
Implementation Method 1
electrochromic polymers that comprise meta-conjugated linkers and aromatic moieties, which present a high transparency in the visible light region in the neutral state. The polymers become highly absorbing in the visible light and near-infrared region and thus colored when their films are being oxidized
Data Source
AI summary
An electrochromic polymer includes a formula ofMCL represents a meta-conjugated linker, and Ac represents an aromatic moiety. The disclosed electrochromic polymer has an absorption onset equal to or smaller than 420 nm in a neutral state and has absorption in visible and/or near-infrared wavelengths in an oxidized state, thus the disclosed electrochromic polymer shows a high transparency and a high optical contrast when used in electrochromic devices.