Plasma Modified V2O5/PEDOT Hybrid Based Flexible Electrochromic Devices

Vanadium oxide/poly (3,4‐ ethylenedioxythiophene)(V₂O₅‐PEDOT) hybrid materials were prepared in a rotating quartz plasma reactor via capacitively coupled radio frequency (RF 13.56 MHz) plasma. Thin films of V₂O₅‐PEDOT hybrid and V₂O₅ were obtained by electron beam evaporation technique onto flexible PET substrate for electrochromic devices (ECDs) applications. As a counter electrode, both RF magnetron sputtered MoO₃ onto ITO coated PET and only ITO coated PET electrodes were used. Characterizations of the films were carried out via using scanning electron microscopy‐energy dispersive X‐ray spectroscopy (SEM‐EDX) and X‐ray diffraction (XRD). Hybrid ECDs results showed that synergistic effect depending on improved stability between V₂O₅ and PEDOT. As a result, we developed all solid complementary electrochromic devices including V₂O₅, V₂O₅‐PEDOT and MoO₃ films. The electrochromic device characteristics such as electrochromic contrast, coloration efficiency, switching time were calculated from optical and electrochemical measurements. The highest coloration efficiency and optical contrast were obtained as 53 cm²/C and 17 % for V₂O₅‐PEDOT/MoO₃‐based ECD.     

High‐performance Flexible Complementary Electrochromic Device Based on Plasma Modified WO3 Nano Hybrids and V2O5 Nanofilm with Low Operation Voltages

Tungsten trioxide‐poly(3,4‐ethylenedioxythiophene) (WO₃‐PEDOT) and tungsten trioxide‐polyfuran (WO₃‐PFu) were prepared by rf rotating plasma polymerization. Electrochromic hybrid thin films were fabricated onto flexible polyethylene terephthalate (PET)/ indium tin oxide (ITO) film using electron beam evaporation method. In order to deeply characterize all films, scanning electron microscopy‐energy dispersive X‐ray spectroscopy (SEM‐EDS) and electrochemical impedance spectroscopy (EIS) techniques were used. The counter electrode effect on plasma modified WO₃ nano hybrids‐based electrochromic devices (ECDs) was evaluated. By incorporating flexible vanadium pentoxide (V₂O₅) film as counter electrode, complementary ECDs were constructed through combining the hybrid flexible films (WO₃‐PEDOT, WO₃‐PFu) as working electrodes, which exhibit highly efficient electrochromic performance with low voltage operation. Especially, WO₃‐PEDOT/V₂O₅‐based ECD owns a high optical modulation of 61.5 % at 750 nm driven by −1.0 V (coloration) and +1 V (bleaching) with fast response times (coloration time: 13.58 s, bleaching time: 8.07 s) and a high coloration efficiency of 527 cm² C⁻¹. This study can supply useful and efficient avenue for designing flexible complementary electrochromic device for energy‐saving flexible electronics.     

Electrochromic properties of MoO<Subscript>3</Subscript> thin films derived by a sol–gel process

Molybdenum trioxide (MoO₃) films were deposited on ITO/Glass substrates by the sol–gel method using a spin-coating technique and heat treated at various temperatures under different ambient atmosphere. Effects of the process parameters on the electrochromic properties of MoO₃ films were studied using cyclic voltammetry (CV) in a propylene carbonate (PC) non-aqueous solution containing 1 M lithium perchlorate (LiClO₄). Electrochromic MoO₃ film on lithium intercalation was investigated by in-situ transmittance measurement during the CV process. The MoO₃ films showed reversible recharge ability on Li⁺/e⁻ intercalation/deintercalation. Experimental results revealed that the heat-treatment temperature, the ambient atmosphere, and the thickness will have the string influence on the electrochromic properties of MoO₃ thin films. X-ray diffraction (XRD) results show that the amorphous MoO₃ films can be obtained with the heat-treatment temperature below 300 °C in O₂ ambient atmosphere. The optimum electrochromic MoO₃ film, with a thickness of 130 nm, exhibits a maximum transmittance variation (ΔT%) of 30.9%, an optical density change (ΔOD) of 0.213, an intercalation charge (Q) of 8.47 mC/cm², an insertion coefficient x in Li _x MoO₃ was 0.21 and a coloration efficiency (η) of 25.1 cm²/C between the colored and bleached states at a wavelength (λ) of 550 nm.     

染料敏化TiO2/WO3薄膜电池的光电变色

The light-to-electricity conversion process of the TiO2 nanostructured electrode sensitized by a dye was investigated using the photoelectrochemical method in this paper. At the same time, the WO3 thin film was electrodeposited on conducting glass. The results showed that the dye-sensitized nanoporous TiO2 film has the properties of energy conversion, along with good electrochromic properties of electrodeposited MoO3 thin film. A self-powered smart window was achieved by combining a dye-sensitized nanoporous TiO2 film as the photovoltaic layer and an electrodeposited WO3 film as the electrochromic layer. This window changed from being almost transparent to blue spontaneously under illumination, and thus could modulate light transmittance.     

Electrochromic properties of WO<Subscript>3</Subscript> and WO<Subscript>3</Subscript>:P thin films

WO₃ and WO₃:P (5 mol% H₃PO₄) thin films were prepared using the sol-gel route and the electrochromic properties of the films were investigated using in situ spectroelectrochemical methods. The measurements were performed in propylene carbonate solution with 0.1 M LiClO₄ as electrolyte. During the cathodic polarization at –0.8 V a blue coloration is observed with a reversible variation between 14% and 84% of the transmittance at λ=633 nm. The kinetics for the bleaching process is faster for the WO₃:P film than for the undoped WO₃ film. Electronic Publication     

Enhancement of electrochemical properties of MoO<Subscript>3</Subscript> nanobelts electrode using PEG as surfactant for lithium battery

Molybdenum trioxide (MoO₃) has attracted considerable attention due to their typical two-dimensional layered structure consisting of double layers of edge- and vertex-sharing MoO₆ octahedral being weakly held together by van der Waals bonds. These MoO₃ nanostructures and their polymer composites are currently drawing interest for the potential applications of Li batteries, supercapacitors, and other electrochemical as well as electrochromic display devices. In this paper, we report the synthesis of MoO₃ nanobelts and polyethylene glycol (PEG) surfactant MoO₃ nanobelts by hydrothermal method. Structure and morphology of the samples were investigated by X-ray diffraction, Fourier transform spectroscopy, scanning electron microscopy, and transmission electron microscopy (TEM). The pure MoO₃ nanobelts show an initial specific capacity of 275 mAh g⁻¹, whereas the 0.5 mol% PEG surfactant MoO₃ nanobelts show 307 mAh g⁻¹ at constant current density of 30.7 mA g⁻¹ with the 1.0–3.0 V vs. Li/Li⁺ potential range. It was found that PEG surfactant MoO₃ nanobelts show not only a high initial specific capacity but also show better cyclic performance compared with that of pure MoO₃ nanobelts. The PEG surfactant MoO₃ nanobelts show stability and improvement of the specific capacity due to decreasing the length, width, and thickness of the nanobelts by surface reaction. Electrochemical impedance spectroscopy reveals that the PEG surfactant MoO₃ nanobelts exhibit low electrode resistance compared with pure MoO₃ nanobelts.     

Electrochromic properties of sputtered TiO2 thin films

TiO₂ thin films were deposited on ITO/Glass substrates by the rf magnetron sputtering in this study. The electrochromic properties of TiO₂ films were investigated using cyclic voltammograms (CV), which were carried out on TiO₂ films immersed in an electrolyte of 1 M LiClO₄ in propylene carbonate (PC). As- deposited TiO₂ thin film was amorphous, while the films post-annealed at 300~600°C contained crystallized anatase and rutile. With the increase of the annealing temperature, the surface roughness of film increased from 1.232 nm to 1.950 nm. Experimental results reveal that the processing parameters of TiO₂ thin films will influence the electrochromic properties such as transmittance, ion-storage capacity, inserted charge, optical density change, coloration efficiency and insertion coefficient.     

WO<Subscript>3</Subscript> thin film coating from H<Subscript>2</Subscript>O-controlled peroxotungstic acid and its electrochromic properties

We prepared PTA coating solution by hot plate evaporation, N₂ bubbling evaporation, and rotary evaporation. N₂ bubbling and rotary evaporation are very efficient way to synthesize PTA which reduces the synthesis process time to 1/5, compared to hot plate evaporation method. Another strong point is that N₂ bubbling and rotary evaporation make it possible to control excess hydrogen peroxide and water contents in PTA. The PTA formula were WO₃·0.13H₂O₂·10.0H₂O for hot plate method, WO₃·0.16H₂O₂·7.1H₂O for N₂ bubbling method, and WO₃·0.15H₂O₂·3.00H₂O for rotary evaporation method. Thermal analysis and mass spectroscopy analysis show that water is evaporated at around 100 °C and hydrogen peroxide is dissociated at the range of 150 and 250 °C. Amorphous phase of WO₃ thin film prepared from rotary evaporated PTA solution has the best electrochromic property, light transmission difference from 91% at its bleached state and 5.5% colored state, and charge density of 22 mC/cm². It is thought that the control of excess hydrogen peroxide and water contents in PTA is very important to enhance the electrochromic properties of WO₃ thin film.     

Hydrothermal synthesis,characterization, and photocatalytic performance of W-doped MoO<Subscript>3</Subscript> nanobelts

Orthorhombic MoO₃ and W-doped MoO₃ nanobelts were successfully synthesized by a hydrothermal method. The effect of W dopant on the photocatalytic performance of W-doped MoO₃ nanobelts was studied. The phase, morphology, and oxidation state of the products were characterized by X-ray diffraction analysis, Fourier-transform infrared and Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. In this research, MoO₃ and W-doped MoO₃ exhibited the same phase and morphology of orthorhombic nanobelts with growth along the [001] direction, including detection of Mo⁶⁺, O^2?, and W⁶⁺ in the 3 mol% W-doped MoO₃ sample. The photocatalytic performance of the as-synthesized MoO₃ and W-doped MoO₃ nanobelts was monitored through photodegradation of methylene blue (MB) under visible radiation. W-doped MoO₃ nanobelts showed better photocatalytic performance than pure MoO₃. The 3 mol% W-doped MoO₃ photocatalyst exhibited very good visible-light-driven activity for photodegradation of MB, as high as 99 % within 60 min.     

X-Ray Analysis of Multi-Films for Electrochromic Device Application

Multilayer films based on tungsten oxide (WO₃), ITO (indium tin oxide) and CdS were deposited mainly by reactive dc magnetron sputtering onto glass substrates for electrochromic application. The thin films were analyzed by means of XPS (X-ray photoelectron spectroscopy), GIXD (grazing incidence X-ray diffraction) and XRD (X-ray diffraction). XRD and XPS results confirmed that the films were WO₃, CdS and ITO, respectively. The surface and interface of the CdS/ITO bi-layered film was studied by GIXD in different incidence angles. Detailed results about the amorphous characterization of the films during room temperature growth and post annealing are given.     

Preparation of MoO3/Pt electrodes by electrodeposition for a direct methanol fuel cell

MoO₃/Pt binary catalysts with various Mo/Pt ratios were prepared by an electrodeposition method for use as the anode in a direct methanol fuel cell. Pt was electrodeposited onto indium tin oxide (ITO) substrate, and then MoO₃ was electrodeposited from an Mo-peroxo electrolyte on the top of Pt with different deposition times. The crystallinity of synthesized films was analyzed by X-ray diffraction (XRD), and the oxidation state of both the platinum and molybdenum were determined by X-ray photoelectron spectroscopy (XPS) analyses. Scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM/EDS) was employed to investigate the surface morphology and composition. The catalytic activity and stability for methanol oxidation were measured using cyclic voltammetry and chronoamperometry in a mixture of 0.5 M H₂SO₄ and 0.5 M CH₃OH aqueous solution. Electrocatalytic activity for CO oxidation was also evaluated in a 0.5-M H₂SO₄ solution. The addition of a proper amount of MoO₃ was found to significantly improve both the catalytic activity and stability for methanol oxidation.     

Improved photovoltaic performance from high quality perovskite thin film grown with the assistance of PC<Subscript>71</Subscript>BM

The strategy of sequentially spin-coating a perovskite film from the perovskite precursor and an electron transporting layer of [6,6]-phenyl-C₇₁-butyric acid methyl ester (PC₇₁BM) is developed to simplify the fabrication procedure of perovskite solar cells. X-ray diffraction and scanning electron microscopy indicate that PC₇₁BM film on perovskite layer can retard the evaporation of dimethyl sulfoxide (DMSO) efficiently, thus prolonging the transformation of intermediate phase to perovskite crystals, leading to a high quality perovskite thin film. The solar cells with the structure of indium tin oxides (ITO)/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/CH₃NH₃PbI₃/PC₇₁BM/bathocuproine (BCP)/Ag made from this simplified method exhibit a higher efficiency (12.68%) than those from the conventional one-step method (9.49%).     

Electrochromic and photoelectrochromic properties of sol–gel derived tungsten trioxide/titania composite thin films

Tungsten trixoide/titania (WO₃-titania) composite thin films with W/Ti molar ratios of 100/0, 98/2, 96/4, 94/6 92/8 and 90/10 were prepared on fluorine-doped tin oxide conducting glass, and their electrochromic (EC) and photoelectrochromic (PEC) performances were investigated in this study. The composite thin films were synthesized by sol–gel process using peroxotungstic acid and titanium (IV) n-butoxide as the precursors. The surface morphology and composition of the composite thin films were characterized using scanning electron microscope with energy dispersive spectrometer. Electrochemical experiments with in situ spectroscopic measurement were employed to study the EC properties of the composite thin films. It was found that the presence of titania in the WO₃ matrix might slightly decreases its EC performance. PEC cells using the composite thin films as the working electrode and a sputtered semitransparent platinum thin film on ITO as the counter electrode were fabricated and their PEC performances were investigated. The device using composite thin film prepared from sol solution with a W/Ti molar ratio of 96/4 exhibited the best PEC performance.     

Synthesis and characterization of chemically grown electrochromic tungsten oxide

Tungsten oxide thin films, which are cathodic coloration materials that are used in electrochromic devices, were prepared by a chemical growth method and their electrochromic properties were investigated. The thin films of WO₃ were deposited onto electrically conducting substrates: fluorine doped tin oxide coated glass (FTO) with sheet resistance of about 10 Ω/cm. Transparent, uniform and strongly adherent thin film samples of WO₃ were studied for their structural, morphological, optical and electrochromic properties. The XRD data confirmed the monoclinic crystal structure of WO₃ thin films. The direct band gap Eg for the films was found to be 2.95 eV which is good for electrochromic device application. The electrochromism of WO₃ thin film was evaluated in 0.5 M LiClO₄/propylene carbonate for Li⁺ intercalation. Electrochromic properties of WO₃ thin films were studied with the help of Cyclic Voltammetry (CV), Chronoamperometry (CA) and Chronocoulometry (CC) techniques.     

Mussel‐Inspired Polydopamine Coating for Flexible Ternary Resistive Memory

In recent years, numerous organic molecules and polymers carrying various functional groups were synthesized and used in fabrication of wearable electronic devices. Compared to previous materials that suffer from poisonousness, stiffness and complex film fabrication, we circumvent above matters by taking advantage of mussel‐inspired polydopamine as our active material to realize resistive random access memories (RRAMs). Polydopamine thin films were grown on indium tin oxide glass catalyzed by Cu₂SO₄/H₂O₂ and characterized by Fourier infrared spectroscopy (FT‐IR), UV/Vis spectroscopy and scanning electron microscopy. The Al/Polydopamine film/ITO devices possess ternary memory behavior with good ternary device yield with two threshold voltages around 1.50 V and 3.50 V, long data retention over 10⁴ s of continuous reading or 10⁴ pulse reading. The two resistance switchings are attributed to defects functioning as charge traps and the formation of conductive filaments. A flexible device based on Al/polydopamine film/ITO/polyethylene terephthalate retains its ternary memory behavior after being bent with a bending radius of 1.54 cm and bending cycles up to 5000, demonstrating good compatibility and flexibility of polydopamine.     

Ag/WO3纳米复合膜的制备及其电致变色性质和器件的研究

通过真空镀膜方法制备的纳米Ag薄膜均匀致密, 表面光滑. 然后通过电化学方法在Ag纳米薄膜上沉积一层三氧化钨(WO3), 制备纳米Ag/WO3复合膜. 并在此基础上构筑五层式玻璃/ITO/纳米Ag-WO3复合膜/固态电解质/聚(3-甲基噻吩)/ITO/玻璃电致变色器件. 实验结果表明, 与传统的WO3膜相比, 纳米Ag/WO3复合膜具有更好的电化学活性、更高的对比度、更短的响应时间, 以及更好的稳定性. 由该复合膜组装的电致变色器件工艺简单, 电致变色性能良好.     

离子液体中聚3-己基噻吩的制备及电致变色性质和器件的研究

以室温离子液体1-丁基-3-甲基咪唑六氟磷酸盐[BMIM]PF₆为溶剂及支持电解质,通过电化学方法制备聚(3-己基噻吩)(PHexT)膜。采用循环伏安法和扫描电子显微镜,对膜的电化学性质及形貌结构进行表征。同时通过紫外可见光谱、计时电流、计时库仑以及计时吸收曲线等方法研究聚合物膜的光谱电化学和电致变色特性,并在此基础上制备PHexT膜的电致变色器件。实验结果表明,在离子液体中制备的PHexT膜光滑致密,掺杂态时为蓝色,脱掺杂时为桔红色,并且具有高的颜色对比度 (40%),较短的响应时间 (2.5 s) 和高的电致变色着色效率 (230cm²/C),该膜制成的固态电致变色器件具有很好的电致变色性能和长的循环寿命。     

In Situ XANES Studies on Extracted Copper from Scrap Cu/ITO Thin Film in an Ionic Liquid Containing Iodine/Iodide

Copper is coated on indium-tin-oxide (ITO) thin film to improve its electrical resistivity. In order to recycle the scrap Cu/ITO thin film, an ionic liquid (1-butyl-3-methyl imidazolium hexafluorophosphate ([C₄mim][PF₆])) containing iodine/iodide (IL-I) was used to extract copper at 303, 343, 413, 374, and 543 K. The extraction efficiency of copper from the scrap Cu/ITO thin film was >99% with IL-I. Using XRD, crystal In₂O₃ was found on the regenerated ITO thin film which had a resistivity similar to that of unused ITO thin film. Using X-ray absorption near edge structural (XANES) spectroscopy, at least two paths for the extraction of copper from the Cu/ITO thin film into IL-I were identified. Path I: Copper is stripped from the scrap Cu/ITO thin film and then interacts with I₃⁻ in the IL-I to form nano CuI. The nano CuI further interacts with I⁻. Path II: Copper interacts with I₃⁻ on the surface of the Cu/ITO thin film to form nano CuI. The nano CuI is further stripped into the IL-I to interact with I⁻. During extraction, the nanoparticle size could be increased in the IL-I by conglomeration due to fewer coordinating anions and decrease in the viscosity of IL-I at high temperatures. Furthermore, nanoparticle growth was affected by [PF₆]⁻ of the IL-I determined via ³¹P NMR.     

Fabrication of a novel Li<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>MoO<Subscript><Emphasis Type="Italic">y</Emphasis></Subscript> film modified electrode and its application as an electrochemical sensor of iodate

A novel organic gel film modified electrode was simply and conveniently fabricated by casting Li_xMoO_y and polypropylene carbonate (PPC) onto the surface of a gold electrode. The cyclic voltammetry and amperometry studies demonstrated that the Li_xMoO_y film modified electrode has a high stability and a good electrocatalytic activity for the reduction of iodate. In amperometry, a good linear relationship between the steady current and the concentration of iodate was obtained in the range from 3×10^–7 to 1×10^–4 mol L^–1 with a correlation coefficient of 0.9997 and a detection limit of 1×10^–7 mol L^–1.     

Selective skeletal isomerization of alkanes over partially reduced MoO<Subscript>3</Subscript>

The surface area and the pentane isomerization activity of Pt/MoO₃ were enlarged by H₂ reduction. The enlargements was observed only when the reduction proceeded through the formation of hydrogen molybdenum bronze, H_xMoO₃. The catalytic activities of H₂-reduced MoO₃ with different noble metals for pentane isomerization and 2-propanol dehydration depended on the ability of noble metal to produce the H_xMoO₃ phases. H₂-reduced Pt/MoO₃ was more active for pentane isomerization than Pt/H, and its activity was comparable to that of Pt/HZSM-5. In heptane isomerization, H₂-reduced Pt/MoO₃ exhibited a lower activity than Pt/H, although heptane was isomerized very selectively. Strong adsorption of heptane onto H₂-reduced Pt/MoO₃ is likely to be a reason for its lower heptane isomerization activity.