Tunable surface plasmon resonance frequencies of monodisperse indium tin oxide nanoparticles by controlling composition,size, and morphology

Monodisperse indium tin oxide nanoparticles (ITO NPs) with high crystallinity have been synthesized by the rapid thermal injection method and the seed-mediated growth method. We demonstrate that the surface plasmon resonance (SPR) frequencies of ITO NPs can be manipulated from 1,600 to 1,993 nm in near-infrared band by controlling the composition, size, and morphology. The doping Sn concentration in ITO NPs could be controlled via changing the %Sn in the initial feed from 0% to 30%. The shortest SPR wavelength at 1,600 nm with 10% Sn doping concentration indicates highest free electron carrier concentration in ITO NPs, which has direct relationship with doping Sn⁴⁺ ions. Furthermore, we demonstrate that the SPR peaks can also be tuned by the size of ITO NPs in the case of uniform doping. Besides, compared with the ITO NPs, single crystalline ITO with nanoflower morphology synthesized through the one-pot method exhibit SPR absorption peak features of red-shifting and broadening.     

Effect of stabilizer on synthesis of indium tin oxide nanoparticles

Indium tin oxide nanoparticles with shapes varying from sphere to cubic were synthesized by controlling the ratio of the concentrations of the protective polymer (PVP) to indium tin oxide precursor in their preparation by co-precipitation. Transmission electron microscopy was used to determine the size and shape. The XPS spectra of the particles revealed that the atomic ratios of In:Sn and (In + Sn):O are 10.0:1.0 and 1.0:1.5, respectively for both of the spheres and the cubes. X-ray diffraction study showed that these particles have the same crystalline structure. Thus, it is shown that the formation of the various shapes of the ITO particles could be achieved by using different ratios of protective polymer instead of varying the protective polymer or the sintering process.     

Effects of linker molecules on the attachment and growth of gold nanoparticles on indium tin oxide surfaces

As a linker molecule to attach gold nanoparticles (AuNPs) on indium tin oxide (ITO) surfaces, cysteamine was examined together with well-known 3-mercaptopropyltrimethoxysilane (MPTMS) and 3-aminopropyltrimethoxysilane (APTMS). Systematic comparisons of AuNPs’ nanostructures formed on ITO were carried out after the room temperature treatment in an ethanol solution of linker molecules followed by the attachment of AuNPs using (i) one-step immersion into the 20-nm Au colloidal solution or (ii) two-step immersion, i.e., a seed-mediated growth treatment. Consequently, in case (i), it was found that APTMS was most effective for denser and homogeneous attachment of AuNPs on ITO surfaces with keeping the dispersion. With the MPTMS or cysteamine linkers in case (i), AuNPs aggregated on the ITO surfaces, and the attached amount of AuNPs were larger with the MPTMS linker. In contrast, in case (ii), nanostructural growth of AuNPs was possible with MPTMS or cysteamine using the seed-mediated growth, while the growth of AuNPs was significantly suppressed with the APTMS linker. Because quite different results were obtained between APTMS and cysteamine, it was found that the attachment and nanostructural growth of AuNPs on the organic linker layers cannot be simply governed by the functional groups, -NH₂, on the outer surfaces.     

粒径均匀的氧化铟粉末的研制

以金属铟，硫酸，氨水为原料，通过工艺条件的选择，制备出过滤性良好的氢氧化铟沉淀物。该沉淀物经过干燥，煅烧不需将氧化物粉碎就可以得到粉末状氧化铟。最佳工艺条件为：反应液中铟离子初始浓度调节在70g/L以下，碱添加量为铟含量的3－4倍；沉淀反应温度控制在90℃以上。     

Indium tin oxide nanoparticles as anode for light‐emitting diodes

Thin films of indium tin oxide (ITO) nanoparticles have been investigated as anode materials for polymer light‐emitting diodes. A luminance efficiency (0.13 cd/A), higher than that (0.09 cd/A) obtained in a control devices fabricated on conventional commercial ITO anodes were found. The thin films were made by spin coating of a suspension followed by annealing. The ITO nanoparticle films have a stable sheet resistance of 200 Ω/sq, and an optical transmittance greater than 86% over the range of 400–1000 nm. Their textural property is also reported. These results demonstrate that ITO nanoparticle can form a high efficient reproducible anode material. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3125–3129, 2006     

Photocatalytic properties of visible-light enabling layered titanium oxide/tin indium oxide films

Visible-light enabling titanium oxide/tin indium oxide (TiO₂/ITO) thin films deposited on unheated glass slides with prolonged deposition duration were investigated in this study. Structural properties characterized by X-ray diffraction (XRD), Raman spectra and scanning electron microscopy (SEM) showed typical polycrystalline structure with primary anatase phase along with elongated pyramid-like grains lying on the film surface and densely packed columnar structure from cross-sectional profile. The XRD preferential peak of (2 1 1) and the Raman peak intensity at 640 cm⁻¹ dramatically increased without noticeable broadening and shift as the deposition time was prolonged beyond 2 h. This implies that more perfectly crystalline structure, less internal stress, and comparatively larger grains were obtained by this technique. The Ti2p_3/2 and O1s XPS peaks shifted toward higher binding energy suggest that the local chemical state was influenced by the prolonged deposition duration in the film, which resulted in red shift of absorption threshold into visible-light region. Under ultra-violet (UV) and visible-light illumination, the visible-light enabling film exhibited the best photocatalytic activity on MB degradation with the rate-constant of about 0.231 h⁻¹. Hydrophilic conversion rate was estimated to be 8.14 × 10⁻³ deg⁻¹ min⁻¹ and long-term UV-induced hydrophilicity of 10° in the dark storage up to 72 h was observed. In addition to its inherent characteristics of the layered TiO₂/ITO structure on hole/electron separation, all these could be attributed to more perfectly formed crystalline structure, densely packed columnar crystals and the surface roughness along with its enlarged surface area.     

氧化铟的制备及制备条件对其结构与性质的影响

介绍了六种氧化铟的制备方法,其中以铟的气相沉积法和直流磁控溅射法制备氧化铟具有较大的优势,这两种方法工艺和技术也比较成熟。此外还介绍了制备条件对氧化铟的微观结构和性质的影响,以及根据对制备参数分析确定最佳制备条件,制备条件在氧化铟的制备过程中起着非常关键的作用。     

Synthesis of polypyrrole/indium tin oxide nanocomposites via miniemulsion polymerization

Polypyrrole/indium tin oxide nanocomposites were synthesized via in situ miniemulsion polymerization of pyrrole monomer in the presence of indium tin oxide nanoparticles. Different nanocomposites were synthesized by different loadings of nano indium tin oxide. The morphology and nanoparticles distribution of the nanocomposites were characterized by electron microscopy. The results of XRD and TEM analysis showed that indium tin oxide nanoparticles were well placed in the polymeric structure of latex. FTIR analysis was used for the characterization of synthesized polypyrrole and its nanocomposites. TGA analysis was performed to investigate the thermal behavior of pristine polypyrrole and its nanocomposites. Conductivities of nanocomposites were measured by 4-point probe method and compared to the neat polymer.     

采用磁控溅射法在细菌纤维素膜上制备高性能的铟锡氧化物薄膜

Microbial cellulose (MC) membranes produced by Acetobacter xylinum NUST4.1,were used as flexible substrates for the fabrication of transparent indium tin oxide (ITO) electrodes.Transparent and conductive ITO thin films were deposited on MC membrane at room temperature using radio frequency (RF) magnetron sputtering.The optimum ITO deposition conditions were achieved by examining crystalline structure,surface morphology and op-toelectrical characteristics with X-ray diffraction (XRD),scanning electron microscopy (SEM),atomic force mi-croscopy (AFM),and UV spectroscopy.The sheet resistance of the samples was measured with a four-point probe and the resistivity of the film was calculated.The results reveal that the preferred orientation of the deposited ITO crystals is strongly dependent upon with oxygen content (O2/Ar,volume ratio) in the sputtering chamber.And the ITO crystalline structure directly determines the conductivity of ITO-deposited films.High conductive [sheet resis-tance ～120 Ω·square-1 (Ω·sq-1)] and transparent (above 76%) ITO thin films (240 nm thick) were obtained with a moderate sputtering power (about 60 W) and with an oxygen flow rate of 0.25 ml·min-1 (sccm) during the deposi-tion.These results show that the ITO-MC electrodes can find their potential application in optoelectrical devices.     

氧化铟纳米粉制备及表征研究

以无机盐为原料，采用液相沉淀法制备纳米氧化铟粉体。研究了沉淀反应条件及沉淀后处理等对纳米氧化铟粉体质量的影响，利用TG-DSC、FT-IR、XRD、SEM和EDS等分析手段对所制纳米氧化铟粉体的结构、粒度、形貌、成分等进行了表征。结果表明：该法制备的氧化铟纳米粉具有立方晶系结构、纯度较高、颗粒均匀呈球形、分散性良好、平均粒径为50nm左右。     

液相共沉淀法制备氧化铟锡超细粉体材料的研究进展

介绍了液相共沉淀法制备氧化锢超细锡粉体材料的工艺,分析了沉淀剂、反应物的浓度、煅烧的温度和时间、分散剂等四个因素对制备过程及产物的影响。按照三氧化铟和二氧化锡的质量比为9∶1选用铟盐和锡盐；用氨水、尿素或碳酸铵作沉淀剂,并且沉淀剂不同,反应时应控制的pH值和反应时间也不同；反应物In~(3+)的浓度0．2mol／L时可得到接近纳米级的超细氧化铟锡粉体材料；700～800℃煅烧3～5h,可使前驱物成为球状,其团聚现象也可以得到综合平衡；分散剂为硫酸铵、硅烷偶联剂KH570等,对其分散机理作了简要的分析。     

Fast switching electrochromism from colloidal indium tin oxide in tungstate-based thin film assemblies

Layer-by-layer assembly was used to alternately deposit tungstate anions with cationic poly(4-vinylpyridine-co-styrene) to generate electrochromic thin films that transit from transparent to dark blue in their oxidized and reduced states, respectively. Tungstate is a good electrochromic material because it is completely colorless in its deposited state, while most other electrochromic materials exhibit some type of color in the absence of an applied voltage. Despite its advantages, tungstates are plagued by long switching time (>30 s), which is common amongst ceramic electrochromics, due to lack of electrical conductivity in at least one of the two states. In an effort to decrease switching time, indium tin oxide (ITO) nanoparticles were incorporated into these tungstate-based assemblies. In the absence of ITO, these films take 30-60 s to completely switch and exhibit reduced contrast with each switch. ITO-containing films, with ITO in every other bilayer, fully switch in 14 s and do not exhibit the same drift in transmittance with repeated switching. ITO allows these films to maintain electrical conductivity in both states, which is the source of this faster, more stable switching. With further optimization, this combination of fast switching and high contrast makes these films promising for use in smart windows and flexible displays.     

Spray-combustion synthesis of indium tin oxide nanopowder

Nanocrystalline indium tin oxide (ITO) powders were prepared by a novel spray combustion method. Using single-drop study equipment, we studied the thermodynamics of the combustion reaction. The reaction can be ignited at air temperature as lower as 171.3°C when using urea and glucose as composite fuel. Once the reaction is ignited, the combustion temperature can surge to above 500°C, generating nanocrystalline ITO powders with grain size about 40 nm. Footages from high-speed camera demonstrated that the reaction is in three-step: moderate beginning, violent middle, and decaying end. It is also noticed that the ignition is very sensitive to the air temperature, even 0.2°C minus deviation may fail the combustion. The combustion reaction is self-sustainable, which saves the energy supply. And the low ignition temperature means the combustion reaction can be carried out in a conventional spray dryer. Our results provide a feasible way to mass production of nanocrystalline ITO powders, which as a methodology, may be extended to the production of other oxide nanopowders.     

Structural,thermal, micromechanical and electrical study of polyimide composite thin films incorporating indium tin oxide

Studies of composite films incorporating inorganic materials are of immense importance for current technological applications. Polyimide (PI) composite thin films incorporating indium tin oxide (ITO) at various weight ratios were processed using an in situ generation approach. The resultant product was imidized up to 350 °C to test the ability of the material to endure high temperatures without affecting the host matrix. The morphological behaviour of the PI/ITO composite films was investigated using Fourier transform infrared, scanning electron microscopy and atomic force microscopy characterization techniques. The degrees of crystallinity and ITO particle size within the PI matrix were studied using X‐ray diffraction. The thermal, structural and electrical properties were analysed using thermogravimetric analysis, differential scanning calorimetry, UV‐visible spectroscopy and the four‐probe technique. The micromechanical properties of the composites were evaluated in terms of tensile strength, tensile modulus and elongation. An overall improvement in the properties of the composite films was observed in comparison to those of pure PI. The synergistic improvement in the composite films is associated with the interaction mechanism between ITO and PI, where ITO becomes dispersed and interacts within the PI matrix. This leads to a decrease in available free‐space volume and increases the surface enrichment providing reinforcement to the matrix. Copyright © 2010 Society of Chemical Industry     

Effect of surface roughness and surface modification of indium tin oxide electrode on its potential response to tryptophan

The effect of surface modification of indium tin oxide (ITO) electrode on its potential response to tryptophan was investigated for ITO substrates with different surface roughness. It was found that a small difference in surface roughness, between ∼1 and ∼2 nm of R_a evaluated by atomic force microscopy, affects the rest potential of ITO electrode in the electrolyte. A slight difference in In:Sn ratio at the near surface of the ITO substrates, measured by angle-resolved X-ray photoelectron spectrometry and Auger electron spectroscopy is remarkable, and considered to relate with surface roughness. Interestingly, successive modification of the ITO surface with aminopropylsilane and disuccinimidyl suberate, of which essentiality to the potential response to indole compounds we previously reported, improved the stability of the rest potential and enabled the electrodes to respond to tryptophan in case of specimens with R_a values ranging between ∼2 and ∼3 nm but not for those with R_a of ∼1 nm. It was suggested that there are optimum values of effective work function of ITO for specific potential response to tryptophan, which can be obtained by the successive modification of ITO surface.     

Structure deformation of indium oxide from nanoparticles into nanostructured polycrystalline films by in situ thermal radiation treatment

A microstructure deformation of indium oxide (In₂O₃) nanoparticles by an in situ thermal radiation treatment in nitrous oxide plasma was investigated. The In₂O₃ nanoparticles were completely transformed into nanostructured In₂O₃ films upon 10 min of treatment time. The treated In₂O₃ nanoparticle sample showed improvement in crystallinity while maintaining a large surface area of nanostructure morphology. The direct transition optical absorption at higher photon energy and the electrical conductivity of the In₂O₃ nanoparticles were significantly enhanced by the treatment.     

Self-catalytic crystal growth,formation mechanism,and optical properties of indium tin oxide nanostructures

In-Sn-O nanostructures with rectangular cross-sectional rod-like, sword-like, and bowling pin-like morphologies were successfully synthesized through self-catalytic growth. Mixed metallic In and Sn powders were used as source materials, and no catalyst layer was pre-coated on the substrates. The distance between the substrate and the source materials affected the size of the Sn-rich alloy particles during crystal growth in a quartz tube. This caused In-Sn-O nanostructures with various morphologies to form. An X-ray photoelectron spectroscope and a transmittance electron microscope with an energy-dispersive X-ray spectrometer were used to investigate the elemental binding states and compositions of the as-synthesized nanostructures. The Sn doping and oxygen vacancies in the In₂O₃ crystals corresponded to the blue-green and yellow-orange emission bands of the nanostructures, respectively.     

聚乙烯吡咯烷酮对纳米氧化铟锡表面修饰研究

以纯金属铟和五水氯化锡为原料,采用化学沉淀法制备氧化铟锡,用聚乙烯吡咯烷酮对铟锡氧化物进行表面修饰。用XPS、XRD、IR和TEM等对表面修饰的ITO纳米粉体进行结构和性能表征,并进行了分散性试验和电学性质的测试,结果表明：所制的ITO纳米粉体呈近似球形,平均粒径为20nm左右,无明显团聚,且结晶性良好;PVP成功链接到ITO纳米粉体表面,达到了表面修饰的作用,在分散溶剂中能稳定存在且不影响其导电性能。     

Nucleation effects on structural and optical properties of electrodeposited zinc oxide on tin oxide

Zinc oxide was electrodeposited from oxygenated aqueous solutions of zinc chloride at 80 C on tin oxide covered glass substrates. A new activation treatment for the substrate is established. This consists in the initial formation, in the deposition solution, of a thin metallic zinc layer (5–50 nm) converted to ZnO by in situ reoxidation. Variable densities of nucleation centers (with values approaching 10¹⁰ cm^–2) are formed by this treatment. This allows control of the formation of a zinc oxide layer ranging from open deposits of isolated crystallites to compact and homogeneous layers. Compact layers have high specular transmission below the band gap value (3.5 eV), whereas open films exhibit extensive light scattering. The shapes of the current–time curves during deposition are discussed in terms of nucleation and structural effects. A possible influence of the semiconducting properties of the films is pointed out.