High-Transparency Electrochromic Polymers for Dual-Spectrum Light Blocking
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Solution Overview
Problem
Conventional conjugated electrochromic polymers (ECPs) have strong absorbance in the visible light region in their neutral state, leading to residual colors and limited optical contrast, and they shift to near-infrared absorption upon oxidation, which is ineffective for thermal management and solar-heat gain control.
Innovation Solution
The development of electrochromic polymers with a polymer backbone comprising meta-conjugated linkers (MCLs) and aromatic moieties (Ars), which are partially conjugated at meta positions, allowing the polymers to be transparent in the neutral state and colored in the oxidized state, synchronizing visible and near-infrared light blocking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional conjugated electrochromic polymers are used, then the polymers are colored in the neutral state, but the optical contrast is limited due to residual colors and the polymers block visible light effectively
Solution Approach 1:
The patent changes the chemical structure parameter of the polymer by introducing meta-conjugated linkers (MCLs) between aromatic moieties. This structural modification alters the electronic conjugation pattern, shifting the absorption characteristics so that the neutral state becomes transparent while the oxidized state absorbs visible light, thereby achieving high optical contrast without residual colors
Solution Approach 2:
The patent creates a composite polymer structure combining meta-conjugated linkers (such as benzene rings or heterocyclic units) with aromatic moieties (such as thiophene, carbazole, or indole units). This composite molecular architecture enables simultaneous achievement of high transparency in neutral state and strong visible light absorption in oxidized state, resolving the contradiction between optical contrast and residual colors
2Illumination intensity
If conventional electrochromic polymers shift absorption to near-infrared region upon oxidation, then the polymers become transmissive in visible light, but thermal management and solar-heat gain control are ineffective
Solution Approach 1:
The patent modifies the absorption spectrum parameter by designing meta-conjugated polymers that absorb in the visible region (400-700 nm) when oxidized, rather than shifting to near-infrared. This parameter change enables the polymer to block both visible light and near-infrared radiation simultaneously, achieving effective thermal management and solar-heat gain control while maintaining visible light transmittance in the neutral state
3Illumination intensity
If the polymer films are made thick to improve optical contrast, then the optical contrast increases, but the highest optical transmittance in the neutral state is limited
Solution Approach 1:
The patent changes the optical property parameter by developing meta-conjugated polymers with extremely low absorption coefficients in the neutral state. This allows thick films (up to several micrometers) to maintain high transparency (T > 90%) in the neutral state, while the same thickness provides strong visible light absorption and high optical contrast (>80%) in the oxidized state, thus resolving the trade-off between optical contrast and transmittance
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 electrochromic polymers achieve high optical contrast and transmittance, enabling effective thermal management and solar-heat gain control by being transparent in the neutral state and absorbing near-infrared light in the oxidized state.
Implementation Method 1
the polymers become highly absorbing in the visible light and near-infrared region and thus colored when their films are being oxidized
Implementation Method 2
synchronizing visible and near-infrared light blocking
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, 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. The electrochromic layer includes an electrochromic polymer having a polymer backbone comprising one or more meta-conjugated linkers (MCLs) and one or more aromatic moieties (Ars). 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. The thickness of the electrochromic layer is from 10 nm to 5800 nm resulting in transmittance of 70%-99.9% at a wavelength of 550 nm at a neutral state of the electrochromic layer.