摘要 :
Electrochromic devices (ECDs) are electrochemical cells composed of thin films and electrolyte that have a property to change the color of transmitted light upon applied potential and,consequently, altering their transmittance and...
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Electrochromic devices (ECDs) are electrochemical cells composed of thin films and electrolyte that have a property to change the color of transmitted light upon applied potential and,consequently, altering their transmittance and reflectance. This property is useful not only for the display industry but also for windows in buildings because it can promote savings of energy spent on air conditioning and lighting. ECDs are composed of two electrodes (ITO coated glasses), an electrochromic layer (WO_3, Nb_2O_5, Prussian blue thin film etc.), a counter electrode (CeO_2-TiO_2 thin film),and an electrolyte that can be liquid, solid, or gel. As electrolyte the most interesting is gel because of its semi-solid state, volume and shape flexibility, good ionic conductivity, and in most cases simplicity in preparation. Gels can be obtained from synthetic and natural macromolecules such as polysaccharides, proteins, and DNA. These macromolecules can be used in their natural form or can be subjected to chemical or physical modifications such as crosslinking or plasticization processes. Different thin films and ECDs, beside the electrochemical characterization, were tested for their optical properties. It was found that the transmittance of thin films depends strongly on their composition. That of ECDs depends of both thin films and the electrolyte. For example, a 40.2% change between the colored and discolored states was observed for the ECD with gelatin-LiClO_4 and 35.2% for the ECD with agar-Eu(CF_3SO_3).
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Black-to-transmissive switching polymer electrochromic devices (ECDs) were designed using a set of spray-processable cathodically coloring polymers, a non-color-changing electroactive polymer poly(2,2,6,6-tetramethylpiperidinyIoxy...
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Black-to-transmissive switching polymer electrochromic devices (ECDs) were designed using a set of spray-processable cathodically coloring polymers, a non-color-changing electroactive polymer poly(2,2,6,6-tetramethylpiperidinyIoxy-4-yl methacrylate) (PTMA) as the charge-compensating counter electrode, and a highly conducting gel electrolyte (6.5 mS cm~(-1)). The color "black" was obtained by utilizing (1) individual copolymers absorbing across the visible spectrum, and (2) blends and bilayers of several polymer electrochromes with complementary spectral absorption. Neutral-state black and ink-like dark purple-blue (or "ink-black") donor—acceptor (DA) copolymers composed of the electron-donor 3,4-propylenediox-ythiophene (ProDOT) and the electron-acceptor 2,1,3-benzothiadiazole (BTD) building units, which possess relatively homogeneous absorption profiles across the visible spectrum, were chosen for their propensity to switch to transmissive states upon electrochemical oxidation. A blend of magenta and cyan polymers (PProDOT-(CH2OEtHx)2 and P(ProDOT-BTD-ProDOT), respectively) was produced with the goal of generating the same dark purple-blue color as that obtained with the "ink-black" DA copolymer. While the multi-polymer ECDs demonstrate high contrasts (up to 50%T), and switch from a saturated purple-blue color (L~* = 32, a~* = 13, b~* = —46) to a light green-blue transmissive state (L~* = 83, a~* = —3, b~* = —6), devices made with the DA electrochromic copolymers switch more than two times faster (0.7 s to attain 95% of the full optical change) than those involving the polymer blends (1.6 s), and exhibit more neutral achromatic colors (L~*=38, a~* = 5, b~*= —25 for the colored state and L~*= 87, a~* = — 3, b~* = -2 for the bleached state, correspondingly). The results obtained suggest that these materials should prove to be applicable in both transmissive- (window-type) and reflective-type ECDs.
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Asymmetric mono cationic 4,4'-bipyridiniums, 1-butyl-4,4'-bipyridinium bromide (BUBP) and 1-methyl-4,4'-bipyridinium iodide (MEBP) showed electrochromic properties from blue to transparent yellow. The electrochromic bipyridiniums,...
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Asymmetric mono cationic 4,4'-bipyridiniums, 1-butyl-4,4'-bipyridinium bromide (BUBP) and 1-methyl-4,4'-bipyridinium iodide (MEBP) showed electrochromic properties from blue to transparent yellow. The electrochromic bipyridiniums, BUBP and MEBP, were introduced to solid state electrochromic cells by using a solution of the bipyridinium, TiO_2, and polymer electrolyte composite. The 4,4'-bipyridinium derivatives was attached to TiO_2 nanoparticles and decreased aggregation of TiO_2 to afford EC dye-TiO_2 nanoparticles with average diameter smaller than 20 nm, as determined by FE-SEM. An all solid state electrochromic cells prepared from the dye-TiO_2 nanoparticles showed improved electrochromic response compared to that without TiO_2. Thus the cell from the BUBP-TiO_2 nanoparticles responded to a step potential of ±2 V within 7 sec with coloration efficiency of 117. The redox cyclability of the bipyridinium-TiO_2 nanoparticles cell was longer than that of the TiO_2 free cells. The enhanced properties were attributed to the conductivity and the large surface area of TiO_2 nanoparticles.
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Here we present an overview of an in situ method of electrochromic polymer characterization based on the CIE system of colorimetry. As illustrated here for PBuDOP (poly(3,4-butylenedioxypyrrole)), colorimetric analysis allows for ...
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Here we present an overview of an in situ method of electrochromic polymer characterization based on the CIE system of colorimetry. As illustrated here for PBuDOP (poly(3,4-butylenedioxypyrrole)), colorimetric analysis allows for precise understanding of color change and the accessible color states of an electrochromic polymer. This technique has proven to be a convenient method for the design and construction of electrochromic devices and promises to reduce trial and error in device construction while allowing for the fine-tuning and reproducibility of color.
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? 2022 Elsevier B.V.Three viologen derivatives: 1,1′- (4-indolyphenyl) -4,4′-bipyridine dihexafluorophosphate (2IV), 1,1′- (4-phenothiazinylphenyl) -4,4′- bipyridine dihexafluorophosphate (2PV) and 1,1′-(4-benzimidazolylpheny...
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? 2022 Elsevier B.V.Three viologen derivatives: 1,1′- (4-indolyphenyl) -4,4′-bipyridine dihexafluorophosphate (2IV), 1,1′- (4-phenothiazinylphenyl) -4,4′- bipyridine dihexafluorophosphate (2PV) and 1,1′-(4-benzimidazolylphenyl)-4,4′-bipyridine dihexafluorophosphate (2BV) were synthesized. The electrochemical and electrochromic properties of these viologen derivatives were investigated. The flexible and rigid electrochromic devices (ECD) were prepared by using the synthesized viologen derivatives as active materials. The structure of the device is ITO-PET (or ITO-glass)/ electrochromic gel film/ ITO-PET (or ITO-glass). The flexible and rigid ECDs exhibited reversible color changes under applied voltage. Upon applied voltage from 0.0 V to ?1.0 V, 2IV-based flexible ECD exhibited optical contrast 61.2% at 695 nm, 2PV-based flexible ECD exhibited optical contrast 60.8% at 715 nm and 2BV-based flexible ECD exhibited optical contrast 53.1% at 574 nm.
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摘要 :
Electrochromic effect has been discovered in many materials with a wide range of applications from visible to infrared, such as smart windows, electronic displays, infrared camouflage, and color‐changeable tactile sensor. However...
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Electrochromic effect has been discovered in many materials with a wide range of applications from visible to infrared, such as smart windows, electronic displays, infrared camouflage, and color‐changeable tactile sensor. However, conventional electrochromic materials cannot meet the growing demand for electrochromic performance in terms of optical contrast, response time, durability, color diversity, and flexibility, which slows down developments in this area. This is mainly due to the limited number and variety of electrochromic materials. In strong contrast, nanoarchitectonics of 2D materials with atomically thin thickness, large lateral size, and diversified series can be an effective way to address these issues and improve the electrochromic performances. This review highlights the recent achievements of emerging 2D electrochromic materials, namely covalent organic frameworks, coordination nanosheets, and transition metal carbides/nitrides/carbonitrides (MXenes). The structures, electrochromic performances and their structure–performance relationship, and future challenges of these materials have been systematically explored. This review can pave a new avenue for the promotion of the nanoarchitectonic 2D materials for the up‐scaled practical electrochromic applications.
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The spectroelectrochemical properties of manganese phthalocyanine (MnPc) thin films are studied. Cyclic voltammetry (CV) and UV-vis in situ spectroelectrochemistry were done to characterize the MnPc thin films. In this study, the ...
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The spectroelectrochemical properties of manganese phthalocyanine (MnPc) thin films are studied. Cyclic voltammetry (CV) and UV-vis in situ spectroelectrochemistry were done to characterize the MnPc thin films. In this study, the insertion of cations during the reduction of MnPc thin films is proposed. Two reversible redox pairs were observed at 0 and -0.9 V (vs. Ag|AgCl) as judged by CVs. According to the absorption spectral data, the reaction at 0 V is related to the transformation between [Mn~(III)Pc~(2-)] and [Mn~(II)Pc~(2-)], and the reaction at -0.9 V is attributed to the transformation between [Mn~(II)Pc~(2-)] and [Mn~IPc~(2-)]. The polychromic characteristics of MnPc thin films were also observed under different redox potentials and can be expressed as follows: 0.5 (light green) → -0.5 (green) → -0.9 (greenish blue) → -1.0 V (purple). The electrochromism of MnPc thin films for use in electrochromic devices (ECD) is also discussed. A complementary ECD, comprising a MnPc and polyaniline (PAni) thin film couple was constructed. This device was darkened and bleached using -1.0 and +1.0 V, respectively. The color of the device was changed from light green to green and the transmittance of the device varied from 60 to 17% at 550 nm.
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In this study, we fabricate a simple, low-cost, high-efficiency, and easy-to-design electrochromic device. Multi-layer graphene (MLG) samples were obtained by chemical vapor deposition method (CVD) at four different growth tempera...
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In this study, we fabricate a simple, low-cost, high-efficiency, and easy-to-design electrochromic device. Multi-layer graphene (MLG) samples were obtained by chemical vapor deposition method (CVD) at four different growth temperatures of 900, 950, 1000, and 1050 degrees C. Electrical and optical characterizations of MLG samples were carried out by transferring them to the polyvinyl chloride (PVC) surface by thermal lamination method. After the characterization of the samples the so called coplanar surface is produced in order to obtain an efficient electrochromic device consisting of a flexible graphene surface without an extra electrode Optical measurements show that threshold voltage for the change in the optical modulation is 2.5V in the near-infrared region and that there exists an increase of 60% just over 3V value. Also, in the electrical characterization studies, a decrease of up to approximately 50% of the layer resistance was seen.
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? 2022 Elsevier LtdNeutral state black electrochromics are prominent materials for smart applications such as displays, car rear views, e-papers etc. This work has aimed to obtain a neutral state black electrochromic polymer, by t...
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? 2022 Elsevier LtdNeutral state black electrochromics are prominent materials for smart applications such as displays, car rear views, e-papers etc. This work has aimed to obtain a neutral state black electrochromic polymer, by tuning the optical absorbance to whole visible region. Two monomers, 4,7-bis(5-(thiophen-2-yl)thiophen-2-yl)benzo[c] [1,2,5]thiadiazole (TTBTT) and 3,4-ethylenedioxythiophene (EDOT), were selected according to their complementary absorbance behaviors, and they were combined in the same polymer backbone via electrochemical copolymerization technique. Copolymerization was performed using three different monomer feed ratios (2:1, 1:1 and 1:2 (EDOT: TTBTT)). Even though all the copolymers exhibited dark to transmissive colors from neutral to oxidized states, changing the monomer feed resulted in different optical contrast, switching response and color hues for each copolymer. The higher optical contrast (from 17% to 27%) and faster switching response (from 3.6 s to 1.8 s) were recorded as EDOT unit increase in the copolymer chain. A dual type electrochromic device was also constructed using the copolymer and the resulting device was successfully changed its color from black to transmissive.
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3-Phenylthieno[3,2-b]thiophene, 3-(4-methoxyphenyl)thieno[3,2-b]thiophene and 3-(4-N,N-dimethylaminophenyl)thieno[3,2-b]thiophene were electropolymerized on ITO by applying constant potentials of 1.7,1.65, and 1.4 V, which had lig...
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3-Phenylthieno[3,2-b]thiophene, 3-(4-methoxyphenyl)thieno[3,2-b]thiophene and 3-(4-N,N-dimethylaminophenyl)thieno[3,2-b]thiophene were electropolymerized on ITO by applying constant potentials of 1.7,1.65, and 1.4 V, which had light transparent reddish yellow, brown and brownish yellow colors, respectively. Their electrochromic devices (ECD) were fabricated with PEDOT on ITO coated glass electrodes. Spectroelectrochemical and electrochromic properties of the devices were investigated in detail. A potential range of 0.0-1.6 V was found to be suitable for operating the devices between pinkish orange and transparent light blue colors. The maximum transmittance difference (%AT) of the ECDs were measured to be 4.5,7 and 3% and the time required to reach 95% of transmittance difference were 2, 1.85, and 1.8 s. They demonstrated good optical memory both in oxidized (with only transmittance changes of 1.5,1, and 2.5%) and reduced states (with almost no transmittance change).
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