Inclined Substrate Deposition of Nanostructured TiO2 Thin Films for DSSC Application

Nanostructured TiO₂ films were deposited onto Indium Tin Oxide (ITO) and glass substrates by dc reactive magnetron sputtering at different substrate inclination angles. The structural and optical properties of the deposited films were studied by X-ray diffraction, scanning electron microscopy and UV–Vis spectrophotometer, respectively. Dye-sensitized solar cells (DSSC) were assembled using these TiO₂ films as photoelectrodes and the effect of the substrate inclination angle in the preparing process of TiO₂ films on the DSSC conversion efficiency was studied.     

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.     

Influence of the substrate type on the microstructural,optical and electrical properties of sol–gel ITO films

Indium tin oxide (ITO) is recognized as the best transparent and conductive material [transparent conducting oxide (TCO)] until now and its properties are dependent on the preparation method. In the present work ITO films with In:Sn atomic ratio 9:1 were prepared by a sol–gel route on different substrates (microscope glass slides, microscope glass covered with one layer of SiO₂ and Si wafers) for TCO applications. The multilayer ITO films were obtained by successive deposition by the dip-coating method and the films were characterized from the structural, morphological, optical, and electrical points of view using X-ray diffraction, scanning electron microscopy, atomic force microscopy, spectroscopic ellipsometry and by Hall effect measurements, respectively. The results showed that the thickness, optical constants and carrier numbers depend strongly on the type of substrate, number of deposited layers and sol concentration. The optical properties of ITO films are closely related to their electrical properties. The enhancement of the conductivity was possible with the increase of crystallite size (which occurred after thermal treatment) and with the reduction of surface roughness.     

氮掺杂二氧化钛-氧化镍双层薄膜的光电致色特性

以金属钛为靶材、O2/N2/Ar混合气氛为溅射气体,在导电玻璃(ITO)表面磁控溅射一层薄膜,再经300-500℃退火处理制备了氮掺杂TiO2薄膜.采用X射线衍射(XRD)、X光电子能谱(XPS)、扫描电子显微镜(SEM)和紫外-可见吸收光谱等对薄膜的微观结构、光学特性和光电化学性能等进行了研究.进而采用化学沉积的方法在TiO2-xNx薄膜表面沉积上一层多孔NiO薄膜,研究表明,制备的ITO/TiO2-xNx/NiO双层薄膜具有明显的光电致色特性,400℃退火处理的氮掺杂TiO2薄膜具有最高的光电流响应,经氙灯照射1h后,薄膜从无色变成棕色,500nm波长处光透过率从79.0%下降至12.6%.     

高光学质量氮化碳薄膜的制备和表征

氮化碳(graphitic carbon nitride,g-CN)作为一种非金属半导体材料已被广泛应用于多种能源相关领域研究中。目前由于制备高质量g-CN薄膜的困难,大大限制了其在实际器件上的应用。本文中,我们报道了一种可制备高光学质量gCN薄膜的方法:即由三聚氰胺先通过热聚合制备本体g-CN粉末,再由本体g-CN粉末经过气相沉积在ITO导电玻璃或钠钙玻璃基底上制备g-CN薄膜。扫描电子显微镜和原子力显微镜的测量结果表明在ITO玻璃基底上形成的g-CN薄膜形貌结构均一且致密,厚度约为300nm。扫描电镜能量色散能谱和X射线光电子能谱测量结果表明在ITO玻璃基底上制备的g-CN薄膜的化学组成与本体g-CN粉末的化学组成基本一致。同时,我们发现制备的g-CN薄膜和本体g-CN粉末一样在光照射下可以有效降解亚甲基蓝染料。此外,我们还测量了制备的g-CN薄膜的稳态吸收光谱、稳态荧光光谱、荧光寿命和价带谱,并运用吸收光谱和价带谱数据确定了其能带结构。     

SnO2 thin films doped indium prepared by the sol–gel method: structure, electrical and photoluminescence properties

This paper reports on the preparation, characterization, electrical and optical properties of tin oxide (SnO₂) thin films doped indium prepared by the sol–gel method and deposited on glass substrates with dip coating technique. X-ray diffraction patterns showed an increase in the crystallinity of the films with increase in annealing temperatures. Atomic force microscopy analyses revealed an increase of grain growth with raise in annealing temperature. The film surface revealed positive skewness and kurtosis values less than 3 which make them favorable for OLEDs applications. The lowest resistivity (about 10^?7) was obtained for the ITO films annealed at 500 °C. These films acquire n-type conductivity due to the non-stoichiometric in the films like (interstitial tin atoms) and also due to low indium doping concentration. The optical properties of the films have been studied from transmission spectra. An average transmittance of >80 % in ultraviolet–visible region was observed for all the films. Optical band gap energy (E _gap) of ITO films was found to vary in the range of 3.69–3.81 eV with the increase in annealing temperature. This slight shift of E _gap to higher photon energies could be related to the crystalline nature of the films associated with the decrease in the defect concentration caused by annealing. Photoluminescence spectra of the films exhibited an increase in the emission intensity with increase in annealing temperature. The high temperature annealing would be expected to decrease the density of defects, improve the crystal orientation and reduce the traps for non-radiative transition and also increase the oxidation processes.     

Direct electrodeposition of PbTe thin films on n-type silicon

High quality lead telluride thin films were directly deposited onto n-type silicon (1 0 0) substrates by electrodeposition at room temperature. The deposition mechanism was studied using cyclic voltammetry. The films were characterized by scanning electron microscopy, energy dispersive X-ray, X-ray diffraction, and Fourier transform infrared spectroscopy. The results indicated that the deposited PbTe films exhibited a polycrystalline rock salt structure and good optical properties with a direct band gap of 0.31 eV.     

PEO掺杂氧化镍薄膜的溶胶-凝胶法制备及电致变色性能研究

以无水醋酸镍、乙醇为前驱液, 加入适量正丁醇及PEO2000等为稳定剂, 采用改进的溶胶-凝胶法制备了稳定的PEO2000纳米Ni(OH)₂复合溶胶体系, 采用旋涂法在ITO (In₂O₃∶Sn)导电玻璃上形成均匀的氧化镍薄膜. 研究了溶胶组分对成膜性能的影响, 采用TG-DSC分析、X射线衍射仪和扫描电镜, 研究了热处理过程中的结构变化和表面形貌. 循环伏安和可见光透过率测试表明该氧化镍薄膜具有良好的电致变色性能和阳极着色效应.     

Nanocrystalline TiO2/ZnO thin films: fabrication and application to dye-sensitized solar cells

Nanocrystalline TiO2 thin films composed of densely packed grains were deposited onto indium-doped tin oxide (ITO)-coated glass substrates at room temperature using a chemical bath deposition technique. A layer-by-layer (LbL) process was utilized to obtain a 1.418-microm-thick TiO2/ZnO structure. The TiO2 surface was super-hydrophilic, but its hydrophilicity decreased considerably after ZnO deposition. Other TiO2/ZnO films were studied to assess their suitability as photoelectrodes in dye-sensitized solar cells (DSSCs).     

Sol–Gel SiO2-ZrO2 Coatings for Optical Applications

SiO₂-ZrO₂ based nanostructured multilayers films have been prepared by sol–gel processing from metallorganic precursors by low temperature inorganic polymerization reactions. Simultaneous gelation of both precursors was realized. Homogeneous and transparent films were obtained at room temperature by dip- and spin-coating on glass and silicon wafer substrates. Samples with successively deposited layers (1–3 layers) and successive thermal treatments have been also studied. Each deposited layer was thermally treated for 1 h at 300°C. The coatings were characterized by XRD, spectroellipsometry (SE), UV-VIS spectroscopy and AFM methods. The influence of substrates, number of coatings and number of thermal treatments on the optical and structural properties of the films was established. The thickness of three deposited SiO₂-ZrO₂ layers is about 496 nm on glass substrates and 413 nm on the silicon wafer substrate. The films deposited on glass are more porous than those deposited on silicon. The properties of optical waveguide prepared from SiO₂-ZrO₂ layers on silicon substrates will be discussed.     

沉积电位对电沉积ZnS薄膜的影响

采用电沉积方法,在不同沉积电位条件下,在氧化锡铟(ITO)导电玻璃上沉积制备了ZnS薄膜,利用XRD、SEM和UV-VIS测试技术对在不同沉积电位所制备薄膜的晶相结构、表面微观形貌和光学性能进行了表征.研究结果表明:沉积电位在1.5 V—1.7 V范围内制备的ZnS薄膜呈非晶态,其可见光透过率从60 %降低到20 %,薄膜的光学带隙约为3.97 eV.在沉积电位为2.0 V条件下所沉积薄膜为ZnS结晶相和金属Zn混合相,薄膜透过率显著降低.     

New colorless substrates based on polynorbornene‐chlorinated polyimide copolymers and their application for flexible displays

Novel polynorbornene (PNB)‐polyimide (PI) copolymers were synthesized based on poly(N‐phenyl‐exo‐norbornene‐5,6‐dicarboximide) (PPhNI) and chlorinated PI (BPDA/TCDB). Polynorbornene copolymers (PNCs) with diverse compositions of anhydride were synthesized via ring opening metathesis polymerization (ROMP) of N‐phenyl‐exo‐norbornene‐5,6‐dicarboximide (PhNI) and exo‐7‐oxanorbornene‐5,6‐dicarboxylic anhydride(exo‐NA), followed by copolymerization through a reaction with aromatic dianhydride (3,3′,4,4′‐biphenyltetra‐carboxylic dianhydride, BPDA) and tetrachlorinated diamine (2,2′,5,5′‐tetrachlorobenzidine, TCDB). The copolymer (PNIC) films exhibited good optical transparency with a transmittance of around 70% at 400 nm and a good thermal stability with a glass transition temperature at 276–300 °C. These flexible films also resisted most organic solvents and chemicals, such as methanol, acetone, tetrahydrofuran, N‐methylpyrrolidone, ethyl acetate, hydrochloric acid, sodium hydroxide, and hydrogen peroxide, etc. Indium tin oxide (ITO) coated thin films were prepared at various substrate deposition temperatures with a radio frequency (r.f.) planar magnetron sputtering system. The ITO thin films that were deposited onto the PNIC copolymer substrates had good electrical and optical properties. An organic light‐emitting device (OLED) was fabricated using the PNIC copolymer substrate with a structure of PNIC08/ ITO (anode)/hole‐transporting layer (HTL)/emitting & electron‐transporting layer (EM&ETL)/aluminum (cathode). The flexible OLED fabricated on the ITO‐grown PNIC substrate exhibited a performance that was comparable to corresponding ITO‐grown glass substrates. Therefore, the ITO‐grown PNIC substrate could possibly be a promising candidate as a substrate for flexible displays. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1806–1814, 2010     

The influence of various deposition techniques on the photoelectrochemical properties of the titanium dioxide thin film

Thin sol–gel TiO₂ layers deposited on the conductive ITO glass by means of three various deposition techniques (dip-coating, inkjet printing and spray-coating) were used as photoanode in the three-compartment electrochemical cell. The thin TiO₂ films were treated at 450 °C and after calcination all samples possessed the crystallographic form of anatase. The relationship between surface structure and photo-induced conductivity of the nanostructured layers was investigated. It was found that the used deposition method significantly influenced the structural properties of prepared layers; mainly, the formation of defects and their quantity in the prepared films. The surface properties of the calcined layers were determined by XRD, Raman spectroscopy, SEM, AFM, UV–Vis analyses and by the optical microscopy. The photo-induced properties of nanoparticulate TiO₂/ITO photoanode were studied by electrochemical measurements combined with UV irradiation.     

Infrared reflection-absorption characterization of TiO2 films on ITO: detection of LO modes

By exploiting the high reflectivity of ITO substrates in the infrared and the detection of longitudinal optical (LO) modes provided by oblique incidence of radiation (Berreman effect), we showed that reflection-absorption experiments in the MID-IR can be successfully performed when thin inorganic oxide films deposited on ITO are used as samples. The samples we used were TiO₂ films deposited on ITO by a sol-gel method. After being annealed at different temperatures, the films presented different structures, which could be detected by the IR spectra. Cyclic voltammograms of the samples were also presented and correlated to the IR spectra. Since we expect that other inorganic oxides can yield similar results, this simple, non-destructive and inexpensive technique can be routinely used in an electrochemical laboratory.     

Synthesis and effect of post-deposition thermal annealing on morphological and optical properties of ZnO thin film

Zinc oxide thin films have been deposited on glass substrates by the chemical bath deposition method; a surfactant, cetyltrimethylammonium bromide (CTAB); was used as capping agent. The films were annealed at two different temperatures: 200 and 300 °C. The structural features were investigated by X-ray diffraction analysis which exhibited hexagonal wurtzite structures along with c-axis orientations. Crystallite size was estimated and found to be around 33–41 nm. The effect of post-deposition thermal annealing on the morphological and optical properties has been investigated by scanning electron microscopy and photoluminescence spectra at room temperature. The band gap energies of uncapped and CTAB-capped ZnO films were found to be 3.28 and 3.48 eV, respectively.     

Electrodeposition of micro- and nanocrystalline lead selenide from alkaline selenosulfate solutions

Cathodic electrodeposition of PbSe is carried out in aqueous alkaline selenosulfate (SeSO ₃ ^2? ) bath of lead complex ions at various conditions of electrolysis. Micro- and nanocrystalline PbSe thin films were grown onto glassy carbon (GC) substrates by potentiostatic and cyclic voltammetric (CV) methods respectively. Structure and surface morphology of thin films were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). X-ray diffraction indicates that the PbSe films have cubic structure without any impurities. The SEM micrograph showed the films cover GC substrate completely and consisted of irregular shaped grains.     

Properties and Photoelectrocatalytic Behaviour of Sol-Gel Derived TiO2 Thin Films

Titanium dioxide (TiO₂) thin films have been prepared on indium doped tin oxide (ITO) glass by sol-gel dip-coating method. Properties of the films were determined as a function of heat-treatment by X-ray diffraction, scanning electron microscopy and photoelectrochemical tests. The films heat-treated at higher temperatures show better crystallinity and photoresponse. The microscopic structure on the film after heat-treatment is attributed to the incorporation of organic polymer into the precursor solution. The performance of the electrodes treated at different temperature on photoelectrocatalytic degradation of methyl orange was investigated. The effect of applied potential and the ability of the electrode to be repeatedly used in photoelectrocatalytic degradation were also evaluated.     

Simple chemical route for nanorod-like cobalt oxide films for electrochemical energy storage applications

We used a simple chemical synthesis route to deposit nanorod-like cobalt oxide thin films on different substrates such as stainless steel (ss), indium tin oxide (ITO), and microscopic glass slides. The morphology of the films show that the films were uniformly spread having a nanorod-like structure with the length of the nanorods shortened on ss substrates. The electrochemical properties of the films deposited at different time intervals were studied using cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS). The film deposited after 20 cycles on ss gave the highest specific capacity of 67.6 mAh g^?1 and volumetric capacity of 123 mAh cm^?3 at a scan rate 5 mV s^?1 in comparison to 62.0 mAh g^?1 and 113 mAh cm^?3 obtained, respectively, for its counterpart on ITO. The film electrode deposited after 20 cycles on ITO gave the best rate capability and excellent cyclability with no depreciation after 2000 charge–discharge cycles.     

两种不同Pb源对PbSe纳米晶生长的影响

采用有机相合成法, 分别以PbO和醋酸铅[Pb(Ac)₂]作为铅源, 研究了在不同反应温度和反应时间下, 不同铅源对PbSe纳米晶生长的影响. 实验结果表明, 以PbO作为铅源, 油酸(OA)作为配体时, 在不同的反应温度下得到了球形PbSe纳米晶和截角八面体PbSe纳米晶; 选择Pb(Ac)₂作为铅源时, 在不同的温度下得到了PbSe纳米花和PbSe纳米星. 选择不同铅源得到的PbSe纳米晶形貌完全不同, 这主要是由于醋酸根的引入产生了不同的空间位阻, 引起纳米晶导向吸附并形成纳米花. 而随着反应温度的升高和反应时间的延长, 这些不同形貌的PbSe纳米晶最终会演变成纳米立方块, 这主要是由PbSe的晶体特性决定的.     

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。