多聚配合物法制备三氧化钨电致变色膜

本文采用多聚配合物法制备三氧化钨电致变色膜，浸涂液是在离子交换后的钨酸溶液中加入双氧水。在不同的温度处理下可得到非晶态和晶态氧化钨电致变色膜，对制得的膜进行了光学及电化学测定，并对材料热处理过程进行了红外分析，热重－差热分析，X射线衍射分析及扫描电镜形貌观察，实验表明，用该法制得的氧化钨膜其电致变色特性可与其它方法制备的膜相媲美。     

Highly Stable Ag–Au Core–Shell Nanowire Network for ITO-Free Flexible Organic Electrochromic Device

Solid and flexible electrochromic (EC) devices require a delicate design of every component to meet the stringent requirements for transparency, flexibility, and deformation stability. However, the electrode technology in flexible EC devices stagnates, wherein brittle indium tin oxide (ITO) is the primary material. Meanwhile, the inflexibility of metal oxide usually used in an active layer and the leakage issue of liquid electrolyte further negatively affect EC device performance and lifetime. Herein, a novel and fully ITO-free flexible organic EC device is developed by using Ag–Au core–shell nanowire (Ag–Au NW) networks, EC polymer and LiBF₄/propylene carbonate/poly(methyl methacrylate) as electrodes, active layer, and solid electrolyte, respectively. The Ag–Au NW electrode integrated with a conjugated EC polymer together display excellent stability in harsh environments due to the tight encapsulation by the Au shell, and high area capacitance of 3.0 mF cm⁻² and specific capacitance of 23.2 F g⁻¹ at current density of 0.5 mA cm⁻². The device shows high EC performance with reversible transmittance modulation in the visible region (40.2% at 550 nm) and near-infrared region ( − 68.2% at 1600 nm). Moreover, the device presents excellent flexibility ( > 1000 bending cycles at the bending radius of 5 mm) and fast switching time (5.9 s).     

Electrochromic Effect in Titanium Carbide MXene Thin Films Produced by Dip‐Coating

MXenes, a large family of 2D transition metal carbides and nitrides, have shown potential in energy storage and optoelectronic applications. Here, the optoelectronic and pseudocapacitive properties of titanium carbide (Ti₃C₂T_x) are combined to create a MXene electrochromic device, with a visible absorption peak shift from 770 to 670 nm and a 12% reversible change in transmittance with a switching rate of <1 s when cycled in an acidic electrolyte under applied potentials of less than 1 V. By probing the electrochromic effect in different electrolytes, it is shown that acidic electrolytes (H₃PO₄ and H₂SO₄) lead to larger absorption peak shifts and a higher change of transmittance than the neutral electrolyte (MgSO₄) (Δλ is 100 nm vs 35 nm and ΔT_{770 nm} is ≈12% vs ≈3%, respectively), hinting at the surface redox mechanism involved. Further investigation of the mechanism by in situ X‐ray diffraction and Raman spectroscopy reveals that the reversible shift of the absorption peak is attributed to protonation/deprotonation of oxide‐like surface functionalities. As a proof of concept, it is shown that Ti₃C₂T_x MXene, dip‐coated on a glass substrate, functions as both transparent conductive coating and active material in an electrochromic device, opening avenues for further research into optoelectronic and photonic applications of MXenes.     

Electrosynthesis of polyfuran in acetonitrile–boron trifluoride–ethyl ether mixture and its device application

Electrochemical polymerization of furan was achieved in acetonitrile/boron trifluoride/ethyl ether (CH₃CN/BF₃/EE) mixture in the presence of tetrabutylammonium tetrafluoroborate via constant potential electrolysis at 1.4 V versus Ag/AgCl. Electrochemical behavior of furan was investigated in the same solvent mixture of varying ratios, utilizing cyclic voltammetry. Free‐standing polyfuran (PFu) films were obtained in CH₃CN/BF₃/EE mixture (2/4/4; v/v/v) and characterized using FTIR spectroscopic technique. Spectroelectrochemical behavior of the PFu film was investigated by recording the electronic absorption spectra, in situ, in monomer‐free solution. It is observed that PFu film can be reversibly cycled between –0.1 V (gray) and + 0.6 V versus Ag‐wire (gray color); however, this behavior diminishes in the presence of water. Electrochromic device application of PFu film with poly(ethylene dioxythiophene) was also studied. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 871–876, 2007     

Tuning of electrochromic properties by copolymerization of monoalkoxythiophenes and dialkoxythiophenes

Monoalkoxysubstituted and dialkoxysubstitued thiophene monomers were synthesized by the nucleophilic substitution and transetherification reactions. Electrochemical homopolymerization of 3‐octyloxythiophene (OOT) and 3,4‐dioctyloxythiophene (DOOT), copolymerization of OOT with DOOT were performed via potentiodynamic and potentiostatic methods in the supporting electrolyte. Both the copolymer and homopolymers were characterized via cyclic voltammetry, scanning electron microscopy, gel permeation chromatography, and spectroelectrochemical analysis. In the redox process of the polymers, it was linear relationship between the peak current and the scanning rate in their cyclic voltammograms. The copolymer of P(OOT‐co‐DOOT) showed obvious change of color between red and bright blue in reduced and oxidized states, that has a great difference with the homopolymers. The morphology studies indicated that the electrochemical deposition of P(OOT‐co‐DOOT) proceeds via a mechanism of nucleation and two‐dimensional growth. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

A complementary electrochromic device based on polyaniline tethered polyhedral oligomeric silsesquioxane and poly(3,4-ethylenedioxythiophene)/poly(4-styrene sulfonic acid)

A high-contrast complementary electrochromic device based on polyaniline (PANI) tethered polyhedral oligomeric silsesquioxane (POSS) (POSS-PANI) and poly(3,4-ethylenedioxythiophene)/poly(4-styrene sulfonic acid) (PEDOT:PSS) is assembled. The electrochromic properties, cyclic voltammetry behavior and coloration efficiency of the device are studied. Due to the loosely packed structure, POSS-PANI gives rise to a significantly higher electrochromic contrast, coloration efficiency and faster switching speed than PANI. Despite its high contrast, the combination of POSS-PANI with PEDOT:PSS still shows synergy in terms of contrast enhancement, which can be attributed to the additional driving force for the diffusion of dopants into PEDOT:PSS provided by the dedoping of POSS-PANI.     

Synthesis and characterization of thiophene functionalized polystyrene copolymers and their electrochemical properties

Thiophene functionalized polystyrene samples (TFPS) were synthesized by atom transfer radical polymerization (ATRP) of styrene, followed by Suzuki coupling with 3‐thiophene (Th) boronic acid. Conducting graft polymer of TFPS with thiophene was achieved at 1.5 V in tetrabutylammonium tetrafluoroborate/dichloromethane (TBAFB/DM) by electrochemical methods. Spectroelectrochemical analysis of the resulting copolymers [P(TFPS‐co‐Th)] reflected electronic transitions at 449, 721 and 880 nm, revealing π ? π* transition, polaron and bipolaron band formation, respectively. We also successfully established the utilization of dual type complementary colored polymer electrochromic devices using P(TFPS‐co‐Th)/poly(3,4‐ethylenedioxythiophene (PEDOT) in sandwich configuration. The switching ability, stability and optical memory of the electrochromic device were investigated by UV–visible spectrophotometry and cyclic voltammetry. Device switches between brown and blue color with a switching time of 1.3 s were prepared with optical contrast (%ΔT) of 25 %. Copyright © 2005 Society of Chemical Industry     

Effects of surface porosity on tungsten trioxide(WO3) films’ electrochromic performance

In this paper, the correlation between the electrochromic performance and the surface morphology of the tungsten trioxide (WO₃) thin films sputtered by dc reactive magnetron sputtering with widely varying target-substrate distances was investigated. It is found that the optical density change (ΔOD) of films is strongly affected by the target-substrate distance. The coloration efficiency (CE) at 633 nm was also found to be sensitive to the target-substrate distance, with 16 cm²/C of film sputtered at 6 cm and 50 cm²/C at 18 cm. X-ray diffraction showed that the crystal structure of films was amorphous. By using atomic force microscope to identify the surface porosity of the sputtered WO₃ films, we found that the film at longer target-substrate distance was rough, porous, and having a cone-shaped columns morphology, thus offering a good electrochromic performance for opto-switching applications.     

Preparation of electrochromic Ni1−xO and TiO2 coatings from pigment dispersions and their application in electrochromic foil based devices

Thin (100–400 nm) electrochromic TiO₂ and Ni_1−xO coatings providing transmissive light modulation were made from an anatase pigment dispersion obtained by co-grinding nanocrystalline titanium particles (6–10 nm in size) with trisilanol heptaisobutylsilsesquioxane as dispersant, while Ni_1−xO based pigment dispersions were made by milling pre-prepared Ni_1−xO pigment with nickel oxyhydroxide (NiO_xH_y) dispersant. Dispersions were obtained by milling the pigments with zirconia beads of various sizes (0.1, 0.2 and 0.4 mm) and the particle size was determined with the dynamic light scattering technique (DLS). Pigment dispersions were deposited by spin-coating on glass and plastic (PET) film and thermally treated at 150 °C to obtain thin TiO₂ and Ni_1−xO pigment coatings. SEM and AFM were used for determination of the surface morphology, revealing their homogenous structure and low surface roughness (up to 20 nm). The optical transmittance and haze of the coatings deposited on glass and PET film were determined from the UV–vis spectra. Their electrochromic effect was analyzed by electrochemical charging/discharging the coatings in a LiClO₄/PC electrolyte. The results demonstrated a convenient, simple and robust technique for making “electrochromic paint” coatings. Pre-prepared TiO₂ and pigments were used for construction of foil-based electrochromic devices with transmissive modulation of light.     

On‐Substrate Preparation of an Electroactive Conjugated Polyazomethine from Solution‐Processable Monomers and its Application in Electrochromic Devices

An electroactive polyazomethine is prepared from a solution processable 2,5‐diaminothiophene derivative and 4,4′‐triphenylamine dialdehyde by spray‐coating the monomers on substrates, including indium tin oxide (ITO) coated glass and native glass slides. The conjugated polymer was rapidly formed in situ by heating the substrates at 120 °C for 30 min in an acid saturated atmosphere. The resulting immobilized polymer is easily purified by rinsing the substrate with dichloromethane. The on‐substrate polymerization is tolerant towards large stoichiometry imbalances of the comonomers, unlike solution step‐growth polymerization. The resulting polyazomethine is electroactive and it can be switched reversibly between its neutral and oxidized states both electrochemically and chemically without degradation. A transmissive electrochromic device is fabricated from the immobilized polyazomethine on an ITO electrode. The resulting device is successfully cycled between its oxidized (dark blue) and neutral (cyan/light green) states with applied biases of +3.2 and ‐1.5 V under ambient conditions without significant color fatigue or polymer degradation. The coloration efficiency of the oxidized state at 690 nm is 102 cm² C^?1.