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Electrosynthesis and characterizations of a multielectrochromic copolymer based on aniline and <i>o</i> -nitroaniline in visible-infrared region
摘要： An IR electrochromic ?lm constructed by copolymer of aniline and o-nitroaniline has been successfully prepared by cyclic voltammetry. The effects of polymerization of aniline and o-nitroaniline on electrochromic properties and optical properties were investigated by cyclic voltammetry, scanning electron microscopy, FTIR spectrometer, and UV–vis spectrophotometer. The results indicate that the ?lm can exhibit three colors (apple green, dark green, and dark blue) at different voltages of ?0.1, 0, and 0.8 V. Simultaneously, a fast response time (1.89 and 4.47 s), a high coloration ef?ciency, a signi?cant optical modulation (60% between ?0.1 and 0.8 V) and a large average emissivity range (Δε max = 0.203) are achieved for the new ?lm.
关键词： emissivity,aniline,electrochromism,copolymer,o-nitroaniline
更新于2025-09-10 09:29:36
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Bionic SiO2@Fc(COCH3)2 Core-Shell Nanostructure for Enhancing the Electrochromic Properties of Ferrocene
摘要： Although the properties of electrochromic materials (ECMs) have been enhanced using fabricated porous materials, the effect of materials porosity on such an enhancement remains unclear. Here, we report a novel ECMs with an adjustable pore hierarchy based on quasi-amorphous and ordered arrays of SiO2@Fc(COCH3)2. ECMs with different pore systems were generated by modifying Fc(COCH3)2 concentration and self-assembly temperature. The composition and core-shell structure of the SiO2@Fc(COCH3)2 nanospheres were confirmed through scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FT-IR) and EDX mapping. The influence of adjustable pore system on the electrochemical behavior was studied. Experimental results showed that the current density of the redox couple peaks of the quasi-amorphous porous SiO2@Fc(COCH3)2 films are considerably lower than those of the ordered porous films but are higher than those of the dense Fc(COCH3)2 films. At 550 nm, the transmittance variation of the quasi-amorphous porous SiO2@Fc(COCH3)2 film is 19 %, whereas that of the ordered porous film is 35 %. The coloration and bleaching times of the quasi-amorphous porous SiO2@Fc(COCH3)2 film are 17.1 s and 4.5 s, respectively, whereas those of the ordered porous film are only 16.5 s and 3.5 s, respectively. Furthermore, the porosities of the films are solved numerically by the finite-element method. For the ordered porous SiO2@Fc(COCH3)2 film, the porosity is 0.26, while the quasi-amorphous film became larger (0.31～ 0.41). This work is the first step in combining ferrocene derivative and colloidal crystal porous structures to develop a green, simple and efficient electrochromic process.
关键词： electrochromism,adjustable porosity,colloidal crystals,ferrocene derivatives,core-shell structure
更新于2025-09-09 09:28:46
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Multilayered Electrochromic Films of Metal Hexacyanoferrates Nanoparticles
摘要： Multi-layered thin films exhibiting electrochromism have been developed using sequential coating processes with water-dispersible nanoparticles of metal (Fe, Ni) hexacyanoferrates. To fabricate the multi-layered films, a simple method is developed to avoid re-dispersion of the water-dispersible film using a dip-washing process in aqueous solutions of metallic salt. On the one hand, the thickness of the multi-coated film of the nanoparticles of iron hexacyanoferrate (FeHCF: Prussian blue) is estimated to be 100 nm, 190 nm, 300 nm, and 420 nm for single, double, triple, and quadruple layers, respectively, and the optical absorbance of the multi-coated film shows dense color proportional to the number of coatings. On the other hand, the double-layered film composed of FeHCF and nickel hexacyanoferrate (NiHCF) layers of thicknesses estimated to be 110 nm and 840 nm, respectively, shows electrochromism among green, blue, and colorless, where green is the blend of the colors of FeHCF and NiHCF.
关键词： metal hexacyanoferrate,Prussian blue,electrochromism,multilayered film,spin-coating,nanoparticle
更新于2025-09-09 09:28:46
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Understanding perceived color through gradual spectroscopic variations in electrochromism
摘要： A bias-dependent in situ Raman scattering and UV–Vis absorption spectroscopic change has been correlated with the corresponding color change of an electrochromic device in an attempt to explain how to understand the relationship between actual perceived color and its absorption/transmittance spectra. For this, the bias across an electrochromic device was increased gradually, rather than abruptly turning ON and OFF, to see subtle variations in Raman and absorption spectra due to bias. Raman scattering establishes that viologen changes its oxidation state reversibly between two redox species (EV2? to EV??) as a result of bias-induced dynamic redox process. A gradual variation in Raman and absorption spectra, which shows maximum absorption corresponding to the yellow light, accompanies similar variation in color change of the device as visible by naked eye. These spectroscopic results are correlated with the perceived blue color, in the re?ected light, by the eye to understand the actual reason behind this. Maximum absorption of yellow light by the device resulting in blue appearance has been explained using the concept of additive and subtractive primary colors.
关键词： Viologen,Raman spectroscopy,UV–Vis,Electrochromism
更新于2025-09-09 09:28:46