Electrochemical Proton Intercalation in Vanadium Pentoxide Thin Films and its Electrochromic Behavior in the near-IR Region

This work examines the proton intercalation in vanadium pentoxide (V₂O₅) thin films and its optical properties in the near-infrared (near-IR) region. Samples were prepared via direct current magnetron sputter deposition and cyclic voltammetry was used to characterize the insertion and extraction behavior of protons in V₂O₅ in a trifluoroacetic acid containing electrolyte. With the same setup chronopotentiometry was done to intercalate a well-defined number of protons in the H_xV₂O₅ system in the range of x=0 and x=1. These films were characterized with optical reflectometry in the near-IR region (between 700 and 1700 nm wavelength) and the refractive index n and extinction coefficient k were determined using Cauchy ’s dispersion model. The results show a clear correlation between proton concentration and n and k.     

Sol-Gel Derived Hydrated Nickel Oxide Electrochromic Films: Optical, Spectroelectrochemical and Structural Properties

Electrochromic hydrated Ni-oxide films were prepared using a dip-coating technique from a nickel sulphate heptahydrate precursor in combination with glycerol, formamide and polyvinyalcohol. In-situ monochromatic (λ=400 nm) spectroelectrochemical measurements using a potential of −0.4 V to 0.8 V in 0.1M LiOH electrolyte revealed that the electrochromic efficiency was 23.5 cm²/C. The observed colouring/bleaching transmittance of a 100 nm thick film changed during potential cycling (20 cycles) by 45%. Ex-situ FT-IR absorption/reflection measurements performed at near-grazing incidence angle conditions (80°) confirmed transformation of as-deposited α-Ni(OH)₂ phase to β-Ni(OH)₂ at cathodic (bleached state) and β-NiOOH at anodic (coloured state) potentials during extended cycling (200 cycles). Clear evidence of the OH⁻ ions insertion and release of SO ₄ ²⁻ ions from the as-deposited films when soaked (0.5 hour) in 0.1M LiOH are given. These processes are accompanied by the transformation of the residual COO⁻ groups originating from the peptisation with glacial acetic acid into CO ₃ ²⁻ species residing in the films during extensive potential cycling.     

聚苯胺衍生物电致变色薄膜的制备与物性研究

采用循环伏安电化学沉积方式分别制备了聚邻甲氧基苯胺(1)和聚邻甲氧基苯胺/邻硝基苯胺(2)电致变色薄膜, 并通过UV-Vis、分光光度仪、场发射扫描电子显微镜(SEM)对其进行性能表征. 结果显示: 变色膜1在不同电压下能实现湖绿色(U＝－0.5 V)和淡紫色(U＝0.9 V)变化, 响应时间约15 s, 最大透光率变化(DT_max)约10% (500 nm)|变色膜2在不同电压下能实现橄榄绿色(U＝－0.9 V)和深酞蓝色(U＝1.4 V)变化, 响应时间约2 s, 最大透光率变化(DT_max)约为20% (497 nm)|SEM测试得到薄膜2的厚度约550 nm, 且不同颜色状态下其表面形貌及导电性能有较大的差别. 由以上结果可以看出: 电致变色薄膜2比1具有更快的响应速度和较好的颜色对比度, 因此薄膜2是更好的电致变色材料.     

甲胺铅碘前驱体薄膜放置过程中物质结构演变及对后续钙钛矿薄膜的影响

系统研究了甲胺铅碘(MAPbI_3)前驱体薄膜在室温大气中放置过程的物质结构变化过程,发现甲胺铅碘前驱体进一步生成了更多的MAPbI_3钙钛矿,大约220 min后MAPbI_3钙钛矿不再增加而且仍有前驱体。此外还分析了这种结构演变对后续钙钛矿薄膜热退火结果的影响,发现放置后的甲胺铅碘前驱体薄膜退火过程中的X射线衍射强度和紫外-可见吸收均比新制备的薄膜的低,而且通过原子力表面形貌图的对比发现,放置后的薄膜热退火后的薄膜晶体尺寸远小于新制备的甲胺铅碘前驱体薄膜热退火后的晶体尺寸,放置后的薄膜晶体尺寸约为0.2μm,新制备的薄膜晶体尺寸约为1.1μm。主要原因在于:甲胺铅碘前驱体薄膜由于在室温大气中放置过程中多生成了部分甲胺铅碘(MAPbI_3),因此晶体成核数量较多,晶粒数量增加,晶体存在较多缺陷,薄膜结晶度低,所以退火时X射线衍射强度和光谱强度较低,同时晶粒尺寸变小。研究为探讨甲胺铅碘钙钛矿生成机理提供了新的思路和方向,属于甲胺铅碘钙钛矿薄膜性质的基础性研究,对实际生产和工业应用有一定指导意义。     

Crystallization Behavior of SiO2-TiO2 Sol-Gel Thin Films

The aim of this work was to investigate the crystallization behavior of thin films of SiO₂−TiO₂ made by the sol-gel process as function of the TiO₂ content and the temperature and time of heat treatment. Precursor solutions were prepared by hydrolysis of TEOS (tetraethoxysilane) and TPOT (titaniums tetraisopropoxide). Multilayer films were spun on single crystal silicon wafers. The compositions studied were (on a molar percentage basis) 20TiO₂−80SiO₂, 30TiO₂−70SiO₂, 40TiO₂−60SiO₂ and pure TiO₂. The films were heat treated at different temperatures between 300°C and 1200°C, for different periods of time (30 s-90 h). The crystallization kinetics were followed by micro-Raman spectrometry. Grazing incidence X-ray diffraction showed that the films crystallized into one or both of two crystalline phase of TiO₂: anatase and rutile (for pure TiO₂ only). The volume fractions of the crystalline phase varied from very low values (<1%), up to 100%, for a TiO₂ sample heat treated at 800°C for 8 hours. The results show that the volume fraction of crystalline phase is strongly influenced by the heat treatment temperature and also, to a smaller extent, by the heat treatment time. The most important parameter, however, is the composition of the films: the higher their TiO₂ concentration, the lower is the crystallization temperature and the larger is the crystallized fraction.     

Ag/TCNQ薄膜中的传质行为研究

采用真空蒸发的方法在玻璃基板上交替蒸发Ag和TCNQ(四氰基对醌二甲烷), 形成不同厚度的双层膜, 经Ag的固体化学扩散与TCNQ反应, 形成金属有机络合物. 利用透射光谱作为表征, 研究了Ag的传质规律, 给出了60~110 ℃温度下的恒温传质系数k和对应的激活能, 并对传质机制进行了探讨.     

Effect of Annealing on the Electrical Properties of CuxS Thin Films

Copper sulphide CuS was deposited on three substrates; glass, Indium Tin Oxide (ITO) and Ti by using spray pyrolysis deposition (SPD). After depositing CuS thin films on the substrates at 200 °C, they were annealed at 50, 100, 150, and 200 °C for 1 hour. Structural measurements revealed covellite CuS and chalcocite Cu₂S phases for thin films before and after annealing at 200 °C with changes in intensities, and only covellite CuS phase for thin films after annealing at 50, 100, and 150 °C. Morphological characteristics show hexagonal-cubic crystals for the CuS thin film deposited on glass substrate and plates structures for films deposited on ITO and Ti substrates before annealing, these crystals became bigger in size and there were be oxidation and some agglomerations in some regions with formation of plates for CuS on glass substrate after annealing at 200 °C. For Hall Effect measurements, thin films sheet resistivity and mobility increased after annealing while the carrier concentration decreased. Generally, the thin film deposited on ITO substrate had the lowest resistivity and the highest carrier concentration before and after annealing. The thin film deposited on Ti substrate had the highest mobility before and after annealing, which makes it the best thin film for device performance. The objective of this research is to show the improvement of thin films electrical properties especially the mobility after annealing those thin films.     

退火温度对CdSe纳米薄膜的形成及光电性能影响

在室温下,采用循环伏安法在ITO上沉积CdSe纳米薄膜。利用X射线衍射仪(XRD)、场发射扫描电镜(FESEM)、原子力显微镜(AFM)、X射线光电子能谱分析(XPS)、紫外-可见(UV-VIS)分光光度计以及电化学工作站对不同温度退火后的CdSe纳米薄膜的晶体结构、形貌、光学性能、光电化学性能进行表征和测试。结果表明,退火温度对CdSe纳米薄膜的形貌和性能起到关键性作用。薄膜表面平整、厚度均匀,且由呈纳米颗粒状的立方相CdSe构成;经退火后,CdSe纳米颗粒出现不同程度的长大现象,Se含量随退火温度的升高而减少。紫外-可见吸收光谱表明随着退火温度的升高,CdSe纳米薄膜对可见光的吸收发生红移,表明禁带宽度逐渐减小,表现出量子尺寸效应。通过光电流测试表明随着退火温度的升高,CdSe薄膜的光电响应效应显著提高。     

退火温度对CdSe纳米薄膜的形成及光电性能影响

在室温下,采用循环伏安法在ITO上沉积CdSe纳米薄膜。利用X射线衍射仪(XRD)、场发射扫描电镜(FESEM)、原子力显微镜(AFM)、X射线光电子能谱分析(XPS)、紫外-可见(UV-VIS)分光光度计以及电化学工作站对不同温度退火后的CdSe纳米薄膜的晶体结构、形貌、光学性能、光电化学性能进行表征和测试。结果表明,退火温度对CdSe纳米薄膜的形貌和性能起到关键性作用。薄膜表面平整、厚度均匀,且由呈纳米颗粒状的立方相CdSe构成;经退火后,CdSe纳米颗粒出现不同程度的长大现象,Se含量随退火温度的升高而减少。紫外-可见吸收光谱表明随着退火温度的升高,CdSe纳米薄膜对可见光的吸收发生红移,表明禁带宽度逐渐减小,表现出量子尺寸效应。通过光电流测试表明随着退火温度的升高,CdSe薄膜的光电响应效应显著提高。     

Surface Morphology Evolution of a Thin Polymeric Supramolecular Film by Tuning Interactions

Summary: A polymeric supramolecule consisting of symmetric polystyrene‐block‐poly(4‐vinylpyridine) (PS‐b‐P4VP), dodecylbenzenesulfonic acid (DBSA), and 3‐pentadecylphenol (PDP) was formed by proton transfer and hydrogen bonding. The surface morphology of a thin film of the polymeric supramolecule has been investigated. The spherical PS microdomains embedded in a P4VP(DBSA)_1.0(PDP)_1.0 matrix are observed for the as‐cast film because the weight fraction, f_comb, of the P4VP(DBSA)_1.0(PDP)_1.0 blocks is much higher than that of PS as a result of the non‐covalent interactions of P4VP and DBSA and DBSA and PDP. Upon annealing the PS‐b‐P4VP(1:1)(DBSA)_1.0(PDP)_1.0 film at high temperatures, the hydrogen bonding between the DBSA and PDP diminishes, which leads to a change of overall morphology from an ordered sphere to a pitted structure.

AFM topographic image of a PS‐b‐P4VP(1:1)(DBSA)_1.0(PDP)_1.0 thin film.     

Effect of Platinum and Ruthenium Incorporation on Voltammetric Behavior of Nitrogen Doped Diamond‐Like Carbon Thin Films

Nitrogen doped diamond‐like carbon thin films with or without platinum and ruthenium incorporation (N‐DLC or PtRuN‐DLC) were deposited on highly conductive p‐Si substrates by DC magnetron sputtering to study the effect of Pt and Ru doping on the voltammetric performance of the N‐DLC films. The potential windows of these film electrodes were measured in different electrolytic solutions, such as H₂SO₄, HCl and KCl. The cyclic voltammograms obtained from the N‐DLC film electrodes in these solutions showed wide potential windows while the introduction of Pt and Ru into the film electrodes apparently narrowed down the potential windows due to their catalytic activities.     

Molecular Weight Effects on the Glass Transition and Confinement Behavior of Polymer Thin Films

Nanoscale polymer thin films exhibit strong confinement effects on T_g arising from free surfaces. However, the coupled influence of molecular weight (MW) and surface effects on T_g is not well understood for low MW film systems below the entanglement length. Utilizing atomistically informed coarse‐grained molecular dynamics simulations for poly(methyl methacrylate) (PMMA), it is demonstrated that the decrease in free‐standing film T_g with respect to bulk is more significant for low MW compared to high MW systems. Investigation of the local interfacial properties reveals that the increase in the local free volume near the free surface is greater for low MW, explaining the MW dependence of T_g‐confinement behaviors. These findings corroborate recent experiments on low MW films, and highlight the relationship between nanoconfinement phenomena and local free volume effects arising from free surfaces.

     

盘状多酸P_5W_(30)/阳离子聚电解质/氧化石墨烯杂化多层膜的电致变色性能

为了提高薄膜[PEI/P_5W_(30)]_(30)的电致变色性能,将具有大的二维尺寸和良好导电性的氧化石墨烯引入该薄膜中。通过层层自组装(LBL)技术构筑了基于盘状多酸K12.5Nal.5[Na P_5W_(30)O_(110)]·15H_2O(P_5W_(30))、氧化石墨烯(GO)的复合薄膜[PEI/P_5W_(30)/PEI/GO]_(30)(PEI:聚乙烯亚胺),并利用UV-Vis光谱对薄膜的组成及增长进行监测;通过原子力显微镜对薄膜的表面形貌进行考察,利用循环伏安法对薄膜电化学氧化还原性质进行研究;薄膜在外加氧化还原电位下呈现出无色/蓝色的可逆变化,电致变色响应时间在10 s以内;此外,薄膜在阶跃电位0.75 V/-0.75 V下循环150次,电致变色性能没有明显减弱,体现了薄膜良好的电致变色可逆性。氧化石墨烯的引入使薄膜[PEI/P_5W_(30)/PEI/GO]_(30)呈现出响应速度快、抗电疲劳强的电致变色性能,将在电致变色器件领域有广阔的应用前景。     

Synthesis and Characterization of Macroporous Tungsten Oxide Films for Electrochromic Application

Macroporous tungsten oxide films have been prepared by combining a nonhydrolytic sol-gel method with a molecular assembly templating strategy. The material has been prepared by hydrolysis of an ethanolic solution of tungsten ethoxide in the presence of polyethylene glycol (PEG), followed by calcination of the dip-coated films. AFM images indicated that an important morphological diversity can be obtained by simply varying the amount of PEG in the coating solution and the conditions of the heat-treatment. The formation of nanostructures of controlled shapes and patterns (fibrils or striped phases) with relatively uniform channel spacings is accounted for by strong hydrogen bonding interactions between the PEG and the partially hydrolyzed tungsten oxide oligomers. XRD and FTIR data showed that PEG delays the crystallization of WO₃. When compared to sol-gel prepared tungsten oxide fims prepared without PEG, the coloration efficiency of the macroporous films appears to be significantly improved especially in the near-infrared region.     

Improved Electrochromic Performance of Poly(3,4‐ethylenedioxythiophene) by Incorporating a Three‐Dimensionally Ordered Macroporous Structure

In this paper, three‐dimensionally ordered macroporous (3DOM) poly(3,4‐ethylenedioxythiophene) (PEDOT) films were electropolymerized from an ionic liquid, 1‐butyl‐3‐methylimidazolium hexafluorophosphate ([Bmim]PF₆). The electrochromic performances of the 3DOM PEDOT films were studied. The 3DOM films exhibited high transmittance modulation (41.2 % at λ=580 nm), high ionic fast switching speeds (0.7 and 0.7 s for coloration and bleaching, respectively), and enhanced cycling stability relative to that exhibited by the dense PEDOT film. The relationship between the declining behavior of the transmittance modulation and the nanostructure of the film was investigated. A three‐period decay process was proposed to understand the declining behavior. The 3D interconnected macroporous nanostructure is beneficial for fast ion and electron transportation, high ion accessibility, and maintenance of structure integrity, which result in enhanced cycling stability and fast switching speeds.     

Sol-Gel Synthesis of Vanadate-Based Thin Films as Counter Electrodes in Electrochromic Devices

V₂O₅-based thin films were prepared via the sol-gel method in order to obtain semiconductive films suitable as counter electrodes in electrochemical devices (e.g. electrochromic windows). Different metal precursors (nickel 2,4-pentanedionate, NiCl₂, BiCl₃, SbCl₃) were added, after dissolution, into the starting vanadium oxo-triisopropoxide solution in the presence of acetic acid as a chelating agent. Preventing different synthesis conditions due to the ambient moisture, the hydrolysis reaction was carried out in controlled acidic conditions. Stable sols were obtained and thin films were dipped on transparent substrates coated with a conductive layer (ITO, SnO₂:F). Different techniques were employed on as-prepared and heat treated (673 K) films, and the corresponding gels in order to characterize the microstructural, surface and electrochemical features of the samples. Better results were obtained for Ni/V oxides thin films: unless their charge capacity was not very high (10 mC/cm₂), their electrochemical stability was unchanged after 1000 cycles and their transmittance spectra showed high transparency (>80%) in all the visible region during both the intercalation and deintercalation steps. On the other hand, preliminary analysis on Sb/V mixed oxides showed a higher charge capacity but irreversible electrochemical reactions took place during the first working cycles.     

电沉积CuInSe2薄膜的热处理研究

报道了热处理对电沉积ＣｕＩｎＳｅ２薄膜的表观形貌、结构及光电性质的影响。     

LaNiO3衬底上Pb(ZrxTi1－x)O3铁电薄膜及梯度薄膜的制备和研究

报道了在镍酸镧 (LaNiO₃, 简称LNO)衬底上锆钛酸铅 [Pb(Zr_xTi_1－x)O₃, 简称PZT]铁电薄膜及其成分梯度薄膜的结构、介电性能、铁电性能以及热释电性能. 首先通过金属有机化合物热分解(MOD)法在Si(100)基片上制备出LaNiO₃, 薄膜, 再通过溶胶-凝胶(sol-gel)法, 在LNO/Si(100)衬底上制备出Pb(Zr_0.80Ti_0.20)O₃, [PZT(80/20)]和Pb(Zr_0.20Ti_0.80)O₃, [PZT(20/80)]铁电薄膜及其成分梯度薄膜. 经俄歇微探针能谱仪(AES)对制备的梯度薄膜进行了成分深度分析, 结果证实成分梯度的存在. 经XRD分析表明, 制备的梯度薄膜为四方结构和三方结构的复合结构, 但其晶面存在一定的结构畸变. 经介电频谱测试表明, 梯度薄膜的介电常数比每个单元的介电常数要大, 但介电损耗相近. 在10 kHz下, 梯度薄膜的介电常数和介电损耗分别为317和0.057. 经电滞回线的测试表明, 梯度薄膜的剩余极化强度比每个单元都大, 而矫顽场却明显较小. 梯度薄膜的剩余极化强度和矫顽场分别为29.96 μC•cm^-2 和54.12 kV•cm^－1. 经热释电性能测试表明, 室温下梯度薄膜的热释电系数为5.54×10-8 C•cm^－2•K^－1, 高于每个单元的热释电系数.