Nanostructured Indium Tin Oxide Films Research Articles

ZnS:Mn electroluminescent display based on nanostructured indium tin oxide films

Thin-film electroluminescent (TFEL) displays have found applications in various industries and areas due to their unique advantages, where high brightness, a wide temperature range, and reliability are crucial. However, despite their benefits, they also face certain limitations and challenges. TFEL displays typically demand relatively high operating voltages. Total internal reflection in the multilayered structure can significantly impede light extraction from the display. In this study, we propose an optimization of the TFEL display structure to enhance light extraction efficiency and reduce operating voltage. Nanostructured indium tin oxide films, obtained by electron beam evaporation on a heated substrate, were utilized to amplify the electric field in a phosphor layer and to create a non-regular light-scattering relief that effectively breaks internal reflection conditions within the display structure. As a result, the display brightness at operating voltage increased by more than 1.5 times.

Study of annealing temperatures on electrical conductivity and optical properties of nanostructure ITO film as deposited by ion assisted e-beam evaporation

In this research, the electrical and optical properties of nanostructured Indium Tin Oxide (ITO) films were investigated. The ITO films were deposited by ion assisted e-beam evaporation with the glancing angle deposition (GLAD) technique on commercial ITO substrates, followed by annealing treatment. The results of crystal structure showed that the nanostructured ITO films are polycrystalline and cubic bixbyite structure (222). The sheet resistance and average transmission at the visible region were 12.17 W sq−1 and 89 %, respectively. The films presented the lowest resistivity and good transparency, where the sheet resistance and an average transmittance were 11.21 W sq−1 and 91% after annealing. The omnidirectional characteristics for a wide range of incident angle (0 − 80°) of nanostructured ITO film which was annealed at 300 °C had higher optical transmission than films without annealing. This work eventually proved that the plasma treatments have effectively promoted the performance of the dye-sensitized solar cells and confirmed their potentials in the real-world applications.

Pulsed Laser Deposition of Indium Tin Oxide Thin Films on Nanopatterned Glass Substrates

Indium tin oxide (ITO) thin films were grown on nanopatterned glass substrates by the pulsed laser deposition (PLD) technique. The deposition was carried out at 1.2 J/cm2 laser fluence, low oxygen pressure (1.5 Pa) and on unheated substrate. Arrays of periodic pillars with widths of ~350 nm, heights of ~250 nm, and separation pitches of ~1100 nm were fabricated on glass substrates using UV nanoimprint lithography (UV-NIL), a simple, cost-effective, and high throughput technique used to fabricate nanopatterns on large areas. In order to emphasize the influence of the periodic patterns on the properties of the nanostructured ITO films, this transparent conductive oxide (TCO) was also grown on flat glass substrates. Therefore, the structural, compositional, morphological, optical, and electrical properties of both non-patterned and patterned ITO films were investigated in a comparative manner. The energy dispersive X-ray analysis (EDX) confirms that the ITO films preserve the In2O3:SnO2 weight ratio from the solid ITO target. The SEM and atomic force microscopy (AFM) images prove that the deposited ITO films retain the pattern of the glass substrates. The optical investigations reveal that patterned ITO films present a good optical transmittance. The electrical measurements show that both the non-patterned and patterned ITO films are characterized by a low electrical resistivity (<2.8 × 10−4). However, an improvement in the Hall mobility was achieved in the case of the nanopatterned ITO films, evidencing the potential applications of such nanopatterned TCO films obtained by PLD in photovoltaic and light emitting devices.

Study of the Effective Refractive Index Profile in Self-Assembling Nanostructured ITO Films

The optical characteristics and structural features of self-assembling nanostructured indium–tin oxide (ITO) films deposited onto substrates heated above 400°C are studied. Estimations of the distribution profiles of the material and effective refractive index in the films under study are obtained by computer simulation of a medium having spectral dependences of light transmission and reflection coefficients closest to those observed in the experiment. These results are in good agreement with scanning electron microscopy data for these films and make it possible to not only confirm the gradient character of such coatings but also restore some of its features. The further overgrowth of voids in self-assembling nanostructured films by means of the deposition of an additional material amount by magnetron sputtering at room temperature leads to a variation in the effective refractive index profile in them. Thus, it is possible to form transparent conductive films with an efficient refractive index profile adjusted for specific tasks. Adjustment of the refractive index profile in self-assembled ITO films acquires a special value for designing coatings with specified properties by virtue of a limited set of transparent conductive materials.

Photocathode Chromophore–Catalyst Assembly via Layer-By-Layer Deposition of a Low Band-Gap Isoindigo Conjugated Polyelectrolyte

Low band-gap conjugated polyelectrolytes (CPEs) can serve as efficient chromophores for use on photoelectrodes for dye-sensitized photoelectrochemical cells. Herein is reported a novel CPE based on poly(isoindigo-co-thiophene) with pendant sodium butylsulfonate groups (PiIT) and its use in construction of layer-by-layer (LbL) chromophore–catalyst assemblies with a Pt-based H+ reduction catalyst (PAA-Pt) for water reduction. A novel Stille polymerization/postpolymerization ion-exchange strategy was used to convert an organic-soluble CPE to the water-soluble poly(isoindigo-co-thiophene). The anionic PiIT polyelectrolyte- and polyacrylate-stabilized Pt-nanoparticles (PAA-Pt) were codeposited with cationic poly(diallyldimethylammonium) chloride (PDDA) onto inverse opal (IO), nanostructured indium tin oxide film (nITO) (IO nITO) atop fluorine doped tin oxide (FTO), by using LbL self-assembly. To evaluate the performance of novel conjugated PiIT//PAA-Pt chromphore–catalyst assemblies, interassembly hole transfe...

Organosilane-functionalization of nanostructured indium tin oxide films.

Fabrication and organosilane-functionalization and characterization of nanostructured ITO electrodes are reported. Nanostructured ITO electrodes were obtained by electron beam evaporation, and a subsequent annealing treatment was selectively performed to modify their crystalline state. An increase in geometrical surface area in comparison with thin-film electrodes area was observed by atomic force microscopy, implying higher electroactive surface area for nanostructured ITO electrodes and thus higher detection levels. To investigate the increase in detectability, chemical organosilane-functionalization of nanostructured ITO electrodes was performed. The formation of 3-glycidoxypropyltrimethoxysilane (GOPTS) layers was detected by X-ray photoelectron spectroscopy. As an indirect method to confirm the presence of organosilane molecules on the ITO substrates, cyclic voltammetry and electrochemical impedance spectroscopy (EIS) were also carried out. Cyclic voltammograms of functionalized ITO electrodes presented lower reduction-oxidation peak currents compared with non-functionalized ITO electrodes. These results demonstrate the presence of the epoxysilane coating on the ITO surface. EIS showed that organosilane-functionalized electrodes present higher polarization resistance, acting as an electronic barrier for the electron transfer between the conductive solution and the ITO electrode. The results of these electrochemical measurements, together with the significant difference in the X-ray spectra between bare ITO and organosilane-functionalized ITO substrates, may point to a new exploitable oxide-based nanostructured material for biosensing applications. As a first step towards sensing, rapid functionalization of such substrates and their application to electrochemical analysis is tested in this work. Interestingly, oxide-based materials are highly integrable with the silicon chip technology, which would permit the easy adaptation of such sensors into lab-on-a-chip configurations, providing benefits such as reduced size and weight to facilitate on-chip integration, and leading to low-cost mass production of microanalysis systems.

Engineered omnidirectional antireflection ITO nanorod films with super hydrophobic surface via glancing-angle ion-assisted electron-beam evaporation deposition

Growths of the indium tin oxide (ITO) nanorod films have been demonstrated by ion-assisted electron-beam evaporation with the glancing-angle deposition technique based on variation in deposition rate. Investigations have been performed on nanostructured ITO films deposited on ITO-coated commercial substrates in comparison to bare substrates. The physical microstructures have been investigated by grazing-incident X-ray diffraction (GIXRD), field-emission scanning electron microscopy (FE-SEM), and high-resolution transmission electron microscopy (HR-TEM). The electrical, optical, and hydrophobic properties were characterized by four-point probe measurements, UV–Vis–NIR spectrophotometry with angle-dependent technique, and contact angle goniometry, respectively. The results indicated that physical morphologies and nanorod diameters of ITO nanorod films were heavily influenced, and thus could be controlled, by deposition rate. The primary reason was self-annealing effect which occurred during film deposition and was crucial factor towards surface diffusion and film crystallinity. From the optical examinations, ITO nanorods deposited on the ITO-coated glasses exhibited significant improvements on transparent conductive oxide (TCO) properties from reference samples. The proposed ITO materials could therefore function as omnidirectional anti-reflection materials and super hydrophobic surface. This work have also proved that the ITO nanorods prepared by the electron-beam evaporation with the GLAD technique was highly promising for solar cell and optoelectronic applications.

Fabrication and characterization of nanostructured indium tin oxide film and its application as humidity and gas sensors

This paper reports the synthesis and characterization of nanocrystalline indium tin oxide (ITO) and its application as humidity and gas sensors. The structure and crystallite size of the synthesized powder were determined by X-ray diffraction. The minimum crystallite size was found 5 nm by Debye–Scherrer equation and confirmed by transmission electron microscopy image. Optical characterizations of ITO were studied using UV–visible absorption spectroscopy and Fourier transforms infrared spectroscopy. Thermal analysis was carried out by differential scanning calorimetry. Further, the ITO thin film was fabricated using sol–gel spin coating method. The surface morphology of the fabricated film was investigated using scanning electron microscopy images. For the study of humidity sensing, the thin film of ITO was exposed with humidity in a controlled humidity chamber. The variations in resistance of the film with relative humidity were observed. The average sensitivity of the humidity sensor was found 0.70 MΩ/%RH. In addition, we have also investigated the carbon dioxide (CO2) and liquefied petroleum gas sensing behaviour of the fabricated film. Maximum sensitivity of the film was ~17 towards CO2. Its response and recovery times were ~5 and 7 min respectively. Sensor based on CO2 is 97 % reproducible after 3 months of its fabrication. Better sensitivity, small response time and good reproducibility recognized that the fabricated sensor is challenging for the detection of carbon dioxide.

Enhancement of light extraction efficiency of organic light emitting diodes using nanostructured indium tin oxide

Improved outcoupling efficiency of organic light emitting diodes (OLEDs) is demonstrated by incorporating a nanostructured indium tin oxide (NSITO) film between a conducting anode and a glass substrate. NSITO film was fabricated using rf-sputtering at oblique angle (85°). Significant reduction in refractive index and improved transmission of NSITO film was observed. OLEDs were then fabricated onto NSITO film to extract the ITO-glass waveguided modes. Extraction efficiency was enhanced by 80% without introducing any detrimental effects to operating voltage, current density, and angular invariance of emission spectra of OLEDs.

Nanostructured indium-tin-oxide films fabricated by all-solution processing for functional transparent electrodes

We investigated nanostructured indium-tin-oxide (ITO) films fabricated by all-solution processing of ITO nanoparticles and a nanoimprint lithography technique. The nanostructured ITO film with one-dimensional periodicity has low sheet resistance of ~200 Ω/sq, high optical transparency of ~80%, and specific transmission spectra due to light diffractions. By using this ITO film as a transparent electrode and an alignment layer of nematic liquid crystals (LCs), we successfully demonstrate the electro-optic performance of LC devices. This functional transparent electrode can give rise to new photonic devices with nanostructures.