Nanoporous nickel oxide thin films and its improved electrochromic performance: Effect of thickness

Electrochromic properties of chemically bath deposited nanoporous NiO thin films were investigated as a function of film thickness using Ni sulphate precursor, aqueous ammonia and potassium persulphate as complexing and oxidizing agents respectively. The films were characterized for their structural, morphological, optical and electrochromic properties using X-ray diffraction, scanning electron microscopy, FT-IR spectroscopy, cyclic voltammetry, chronoamperometry and optical transmittance studies. X-ray diffraction patterns show that the films are polycrystalline, consisting of NiO cubic phase. Infrared spectroscopy results show the presence of free hydroxyl ion and water in NiO thin films. SEM micrographs revealed nanoporous nature composed of interconnected nanoporous network, forming well defined 3D nano envelopes. The optical band gap energy was found to be decreased from 3.22 to 2.80 eV with increasing film thickness. The electrochromic properties of all the films were investigated in aqueous (KOH) and non aqueous (LiClO₄-PC) electrolyte by means of cyclic voltammetry (CV), chronocoulometry (CC) and optical studies. The transmittance modulations or optical density differences during the coloring/bleaching process were found to be increased with the film thickness. This increment in optical differences led to an increase in coloration efficiency (CE) to about 95 cm²/C, which is two times more than that observed in KOH and response time of 2.9 s for bleaching (reduction) and 3.5 s for coloration (oxidation) observed for the film deposited at 60 min with excellent electrochemical stability up to 3000 c/b cycles in LiClO₄-PC electrolyte.     

PREPARATION OF STAR NETWORK PEG-BASED GEL POLYMER ELECTROLYTES FOR ELECTROCHROMIC DEVICES

An amorphous,colorless,and highly transparent star network polymer with a pentaerythritol core linking four PEG-block polymeric arms was synthesized from the poly(ethylene glycol)(PEG),pentaerythritol,and dichloromethane by Williamson reaction.FTIR and ~1H-NMR measurement demonstrated that the polymer repeating units were C[CH_2-OCH_2O-(CH_2CH_2O)_m-CH_2O-(CH_2CH_2O)_n-CH_2O]_4.The polymer host held well mechanical properties for pentaerythritol cross-linking.The gel polymer electrolytes based on Lithium...     

Synthesis and electrochromic properties of polyimides with pendent benzimidazole and triphenylamine units

Five novel near-infrared electrochromic aromatic polyimides(PIs) with pendent benzimidazole group were synthesized from 4,4'-diamino-4'-(1-benzylbenzimidazol-2-yl)triphenylamine(named as DBBT) with five different dianhydrides via two-step polymerization process, respectively. The maximum UV-Vis absorption bands of these PIs locate at about 335 nm for solid films due to the π-π* transitions. A reversible pair of distinct redox peaks, that were associated with a noticeable color change from original yellow to blue, was observed in the cyclic voltammetry(CV) test. A new absorption peak emerged at 847 nm in near-infrared(NIR) region with increasing voltage in UV-Vis-NIR spectrum, which indicates that PI can be used as NIR electrochromic material. These novel PIs have good electrochemical stability, appropriate energy levels for the highest occupied molecular orbital(HOMO) and the lowest unoccupied molecular orbital(LUMO), in the range of-5.17 e V to-5.20 e V and-2.14 e V to-2.26 e V(versus the vacuum level) determined by cyclic voltammetry method. These values basically consisted with the results of quantum chemical calculation. These polyimides can be used as novel electrochromic and hole transportation materials.     

Flexible Electrochromic Poly(thiophene-furan) Film via Electrodeposition with High Stability

Flexible electrochromic(EC) materials have an urgent demand in the current electronic equipment market due to their technological interest and applications. However, at present, few flexible EC devices developed by industry exist due to some problems and challenges still to be solved such as flexibility. In this work, we have successfully synthesized a novel thiophene-furan(TFu) monomer via Stille coupling reaction,and facilely electrochemically polymerized in a neutral Bu_4 NPF_6-CH_2Cl2 electrolyte system to afford the corresponding poly(thiophene-furan)(PTFu) polymer film with good flexibility. The electrochemical and photoelectrochemical analyses of the as-prepared PTFu demonstrate that it has achieved the improved EC performance compared with pure polyfuran and polythiophene polymers, and as a result it possesses favorable EC parameters manifested as a reasonable ΔT(32.1%), faster response(1.38 s), excellent coloration efficiency(CE, 300.9 cm²·C^-1), and after a continuous redox process up to 2000 s, its optical stability can be maintained at 96%, and even after 3000 s, it can still be maintained at 80%. In addition, the successful assembly of the electrochromic device of PTFu film can easily realize the reversible conversion of the color from orange to gray. All these systematic studies suggest that the as-prepared flexible PTFu film is a promising candidate for EC materials and has great potential interest for versatile EC applications.     

多色显示电致变色聚合物叠层复合薄膜的可控制备

在氧化铟锡透明导电玻璃(ITO)电极上电化学聚合依次得到聚4,4',4″-三[4-(2-联噻吩基)苯基]胺(PTBTPA)和聚3,4-乙烯二氧噻吩(PEDOT)薄膜, 从而可控制备出叠层复合薄膜. 由红外光谱(FTIR)和场发射扫描电镜(SEM)表征了复合薄膜. 紫外-可见吸收光谱和电化学测试结果表明, 相对于PTBTPA薄膜(中性态橙色到氧化态深灰色)与PEDOT薄膜(中性态深蓝色到氧化态浅蓝色)的颜色变化, 叠层复合薄膜在不同的电压下能够展现出从橙色→蓝色→墨绿色的颜色变化, 并保持了较好的电化学活性和光学对比度. 这主要源于中性态吸收光谱和颜色显示互补的电致变色材料的选择. 本文提供了一种简单有效的制备多色乃至全色显示的电致变色材料的方法, 该方法同样适用于其它聚合物电致变色材料体系.     

PAMPSLi/P(MMA-VAc)为基体的聚合物电解质

将聚(2-丙烯酰胺-2-甲基丙磺酸锂)(PAMPSLi)和聚(甲基丙烯酸甲酯-醋酸乙烯酯)[P(MMA-VAc)]与LiClO₄共混, 制备了复合聚合物电解质膜. 用FTIR, TG, XRD, DMA, SEM及电化学交流阻抗和机械性能测试对聚合物及其电解质膜的结构和性能进行了表征. 结果表明, PAMPSLi与P(MMA-VAc)共混后结晶状态发生变化, 交联网络变得密实, 提高了热稳定性和拉伸强度, 聚合物电解质膜含有较多微孔结构, 孔径为5~10 μm; 在20 ℃时, 当n(MMA)∶n(VAc)=2∶8, m(PAMPSLi)∶m[P(MMA-VAc)]=5∶95, m(LiClO₄)∶m(copolymer)=15∶85时, 聚合物电解质膜电导率可达到1.68×10^-3 S/cm, 且电导率未出现随LiClO₄含量的进一步增加而下降的现象. 将此电解质用于全固态电致变色显示器件表现出了优良的性能. 对加入PAMPSLi后聚合物电解质膜电导率和热稳定性提高的原因进行了初步探讨.     

MoO_3电致变色薄膜的XPS研究

近年来 ,随着人们提倡节能和使用洁净能源 ,无机电致变色材料在建筑物采光控制系统和反射率可调表面的应用研究 ,已成为材料领域的一个新热点 .WO3、 MoO3等过渡金属氧化物薄膜具有良好的电致变色效应 ,是人们研究的重点 .其中 MoO3的电致变色效果要好于 IrO2、 TiOx、 CoO及 NiOx等电致变色材料 [1],而且它在可见光区有比 WO3更柔和的色彩 ,使人眼更易于适应其颜色变化 .着色态的 MoO3称为钼青铜 ,其开路记忆也好于钨青铜 [2].故 MoO3电致变色薄膜是极有潜力用于实用化的电致变色器件 .MoO3薄膜常用的制备方法有真空蒸 发、化学气…     

Cyclic voltammetric studies of Prussian blue and viologens within a paper matrix for electrochromic printing applications

The apparent redox response of Prussian blue (PB, iron(III) hexacyanoferrate(II)) within a paper matrix is similar to that found in conventional liquid electrolyte voltammetry using a PB-modified electrode; however part of the response is from PB which adsorbs onto the glassy carbon (GC) working electrode. Application of a Nafion® coating to the PB-impregnated paper matrix prevents transfer of PB to the GC surface. In contrast to the PB system, the redox response of the 1,1′-dimethyl-4,4′-bipyridilium (MV, methyl viologen) system, where both redox states examined are soluble, is confined wholly to the paper matrix. For the case of 1,1′-diheptyl-4,4′-bipyridilium (HV, heptyl viologen), the electrogenerated insoluble radical cation salt adsorbs onto the GC electrode, the KCl-impregnated paper acting simply as the electrolyte medium. PB can be electrogenerated within a paper matrix, with the possible application in monochrome electrochromic printing systems.     

Proton-conducting zirconium phosphate/poly(vinyl acetate)/glycerine gel electrolytes

This work reports on a proton gel electrolyte composed of zirconium phosphate (ZP) particles suspended in a poly(vinyl acetate)/glycerine matrix. The material was studied by X-ray powder diffraction, differential scanning calorimetry, impedance spectroscopy, and spectrophotometry. It had a proton conductivity of 1–0.1 mS/cm at room temperature and remained stable and transparent up to at least 110 °C; it therefore appears suitable for uses in electrochromic devices. The structure of the ZP powder and of the gel is discussed in terms of water removal from interplanar spaces by heating or exfoliation. It is suggested that an exfoliation of the layered structure of ZP by intercalation of glycerine produces a dispersion of ZP nanoparticles in the poly(vinyl acetate)/glycerine matrix.     

Electrochemical and electrochromic properties of novel aromatic poly(amine-amide)s derived from N,N′-bis(4-carboxyphenyl)-N,N′-diphenyl-1,4-phenylenediamine

A series of novel triphenylamine-containing aromatic poly(amine-amide)s were prepared from the dicarboxylic acid, N,N′-bis(4-carboxyphenyl)-N,N′-diphenyl-1,4-phenylenediamine, and various diamines by direct phosphorylation polycondensation. All the poly(amine-amide)s were amorphous, soluble in a variety of organic solvents, and could be solution cast into transparent, tough, and flexible films with good mechanical properties. They had useful levels of thermal stability associated with relatively high glass-transition temperatures (195-280 °C). These polymers exhibited strong UV-Vis absorption bands at 330-346 nm and their photoluminescence showed maximum bands around 516-535 nm in NMP solution. The hole-transporting and electrochromic properties are examined by electrochemical and spectroelectrochemical methods. Cyclic voltammograms of the poly(amine-amide)s prepared by casting polymer solution onto an indium-tin oxide (ITO)-coated glass substrate exhibited two reversible oxidative redox couples at potential 0.73-0.78 V and 1.12-1.18 V, respectively vs Ag/AgCl in acetonitrile solution. All the poly(amine-amide)s exhibited excellent reversibility of electrochromic characteristics by continuous ten cyclic scans between 0.0 and 1.40 V, with a color change from original pale yellowish neutral form to the green and then to blue oxidized forms.