In2O3 SnO2 Research Articles

Fabrication of selective and highly sensitive triethylamine gas sensor using In2O3–SnO2 hollow nanospheres in room temperature activated by UV irradiation

Introducing a groundbreaking solution, a room-temperature (RT, 25 °C) gas sensor addresses complexities in conventional sensors, promising enhanced performance. Synthesized through hydrothermal and thermal calcination processes, SnO2 hollow nanospheres (HNs) are integrated with In2O3 components to bolster sensing capabilities. The sensor detects triethylamine (TEA) gas upon UV light irradiation, owing to its unique surface properties and SnO2–SnO2 and SnO2–In2O3 homo- and heterojunctions. This results in unparalleled sensitivity to TEA gas (Ra/Rg = 34–100 ppm) and an exceptional limit of detection (3.98 ppt), attributed to photo-ionized O2− ions' heightened reactivity. The study proposes superior sensors backed by comprehensive analyses, demonstrating their performance improvements and underlying mechanisms. The optimized sensor design, based on In2O3-appended SnO2 HNs, presents exceptional selectivity, pattern recognition for low TEA gas concentrations, humidity resistance, and reliability under UV irradiation.

Effect of deposition parameters on optical and electrical properties of ZnO–In2O3–SnO2 thin films

A combinatorial study was carried out using a magnetron sputtering system to determine suitable ternary compositions of ZnO–In2O3–SnO2 (ZITO) thin films for optoelectronic applications. Samples were obtained on glass substrates via the co-sputtering of high purity oxide targets. Parameters such as the sputtering gas pressure, deposition time and substrate temperature were studied as the process variables and their effects on the composition, optical, and electrical properties of the thin films were examined in detail. The results have revealed that the samples deposited under a sputtering gas pressure of 10 mTorr and deposition time of 45 min in the Zn-rich region presented the best optical properties (max. 84%), whereas In-rich compositions exhibited better electrical properties (min. 14 Ω/□). More specifically, 61.7 at.% Zn, 31.4 at.% In, and 6.9 at.% Sn was determined as the most suitable ZITO composition for various optoelectronic applications. In addition, the increase in deposition temperature enhanced the optoelectronic properties of the thin film samples as well as their crystal quality.

Low-Temperature Deposited Highly Flexible In–Zn–V–O Transparent Conductive Electrode for Perovskite Solar Cells

Inorganic–organic hybrid perovskite solar cells (PSCs) typically embrace Sn-doped In2O3 (ITO) and F-doped SnO2 (FTO) as transparent electrodes, which are rigid and brittle, retarding the commercialization of flexible PSCs (FPSCs). Here, we fabricated flexible amorphous transparent V-doped In–Zn–O (IZVO) thin films with varied concentrations of V atoms at room temperature. The impacts of V concentration on the chemical, electrical, and optical properties of IZVO thin films were thoroughly investigated. The incorporation of V into IZO was demonstrated to suppress the formation of oxygen vacancies and thus reduce the carrier concentration in IZO. The IZVO thin film affords the best electrode performance with an optimum V concentration of 0.46 atom %. In contrast to the conventional ITO transparent electrodes that require a high processing temperature, the amorphous transparent IZVO electrode deposited at a low temperature without any heating and postannealing process showed a low sheet resistance (∼22.6 Ω/□), high conductivity (∼2210 S/cm), high optical transmittance (∼88.8%), and in particular, excellent mechanical flexibility and fatigue robustness. Therefore, the amorphous transparent IZVO electrode-based perovskite solar cells (PSCs) showed superior performance (14.57%) compared to the amorphous ITO electrode-based PSCs (11.96%), due to the significantly improved short-circuit current density (JSC), open-circuit voltage (VOC), and fill factor (FF). Moreover, the IZVO electrode-based FPSC device retained 77% of its initial power conversion efficiency (PCE) after 100 bending cycles, while the PCE of the amorphous ITO electrode-based FPSC dropped by 80% after only 30 bending cycles. Combining the excellent mechanical flexibility and fatigue robustness, the flexible amorphous IZVO electrode shows great potential for highly efficient flexible photovoltaic applications.

Synthesis and Sensor Characteristics of Nanoscale Thin Films in the In2O3–SnO2 and Y2O3–TbOx(CeOx) Systems

(In2O3)0.95(SnO2)0.05, (TbOх)0.50(Y2O3)0.50, and (CeO2)0.80(Y2O3)0.20 single-phase cubic solid solution xerogels and nanocrystalline powders have been synthesized via coprecipitation of hydroxides. Using these powders as precursors, nanoscale film electroconductive materials on a corundum substrate have been produced by screen printing. The highest speed of sensor response to ozone is attributed to In0.95Sn0.05O1.5 films, reaching 8–10 s at a temperature of 473 K. (TbOх)0.50(Y2O3)0.50 thin film is found to be sensitive to changes in the concentrations of (CO + CO2) (the sensitivity coefficient S = 25.11) and ozone (S = 3.16–7.94). (CeO2)0.80(Y2O3)0.20 film exhibits a sensor response to (CO + CO2) (S = 3.10). This study opens up the prospects of using the obtained nanopowders and relevant thin films as materials for resistive gas sensors operating at oxygen pressures of 103–104 Pa.

Tuning the optical bandgap in multi-cation compound transparent conducting-oxides: The examples of In2ZnO4 and In4Sn3O12

Transparent conducting oxides such as the bixbyite In2O3 and rutile SnO2 systems have large disparities between the optical and fundamental bandgaps, ΔEgOF, because selection rules forbid dipolar transitions from the top of the valence band to the conduction-band minimum; however, the optical gaps of multi-cation compounds with the same chemical species often coincide with their fundamental gaps. To explain this conundrum, we have employed density-functional theory to compute the optical properties of multi-cation compounds, In2ZnO4 and In4Sn3O12, in several crystal structures. We show that a recently proposed mechanism to explain the disparity between the optical and fundamental gaps of M2O3 (M = Al, Ga, and In) applies also to other binary systems and to multi-compounds. Namely, a gap disparity will arise if the following three conditions are satisfied: (i) the crystal structure has inversion symmetry; (ii) the conduction-band minimum is formed by the cation and O s-orbitals; and (iii) there is strong p-d coupling and weak p-p in the vicinity of the valence-band maximum. The third property depends critically on the cationic chemical species. In the structures with inversion symmetry, Zn (Sn) strengthens (weakens) the p-d coupling in In2ZnO4 (In4Sn3O12), enhancing (reducing) the gap disparity. Furthermore, we have also identified a In4Sn3O12 structure that is 31.80 meV per formula unit more stable than a recently proposed alternative model.

Subsolidus phase relationships in the Al2O3–SnO2–ZnO ternary system at 1200 °C in air

We report the subsolidus phase relationships in the Al2O3–SnO2–ZnO ternary system at 1200 °C in air. The phases and lattice parameters of samples were analyzed by powder X-ray diffraction (XRD). Only one type of solid solutions was found in this ternary system, which is Al-substituted zinc stannate spinel ternary compounds of Zn2-xSn1-xAl2xO4-type solid solutions with the solubility limit of x ≈ 0.045 at 1200 °C in air. In comparison with In2O3–SnO2–ZnO and Ga2O3–SnO2–ZnO ternary systems previously reported, the solubility limit of Al3+ (≈4.5 mol %) in the Zn2-xSn1-xAl2xO4-type solid solution is much smaller than those of In3+ and Ga3+ in Zn2SnO4 for the substitution of the Sn4+ site, where In3+ and Ga3+ solubility limits are 90 and 100 mol % at 1275 °C and 1250 °C, respectively, in air. In addition, unlike previous report, no solid solution was found to exist more than 0.5 mol% of Zn2+ in Al2O3 at 1200 °C in air. On the basis of our experimental data, we were able to construct the subsolidus phase diagram of the Al2O3–SnO2–ZnO ternary system at 1200 °C in air.

Structural and Optical Characteristics of Zn-Rich In2O3–SnO2–ZnO (ITZO) Thin Films Prepared by Radio Frequency Magnetron Sputtering

Structural and Optical Characteristics of Zn-Rich In₂O₃–SnO₂–ZnO (ITZO) Thin Films Prepared by Radio Frequency Magnetron Sputtering

A stand-alone flat-plane lighting device in a diode structure employing highly crystalline SWCNTs as field emitters

We have developed and fabricated a visible-light flat plane-emission device in a simple diode structure composed of a cathode containing high crystallized single-walled carbon nanotubes (SWCNTs) dispersed in an organic In2O3–SnO2 precursor solution and a non-ionic surfactant. The SWCNTs were annealed at a high temperature of 1300K in a low-vacuum atmosphere of 10−1Pa to obtain highly crystalline SWCNTs as field emitters. The anode, on the other hand, was fabricated with phosphors coated by ITO film and assembled with the cathode in a cavity separated by glass plates by a stable assembling process to produce a stand-alone flat plane-emission panel, with a stable and high vacuum of under 10−4Pa. This device with its diode structure has a low driving voltage, stable current fluctuation, and low energy loss with electron emission in the cathode electrode. Furthermore, the brightness for power consumption, which is an important factor when comparing luminescent devices, was over 10,000cd/m2 with low power consumption of under 1.0W when using a white phosphor in the simple diode panel. This cathode device in a flat plane-emission panel has the potential to provide a new means of everyday lighting in daily life.

Preparation and characterization of oil-soluble In2O3 nanoparticles and In2O3-SnO2 nanocomposites and their calcined thin films

Oil-soluble In2O3 nanoparticles and In2O3–SnO2 nanocomposites were prepared in oleylamine via decomposition of metal acetylacetonate precursors. Thin films of In2O3 and In2O3–SnO2 were obtained by spin-coating solutions of the oil-soluble In2O3 nanoparticles and In2O3–SnO2 nanocomposites onto substrates and then calcining them. Transmission electron microspectroscopy, scanning electron microspectroscopy, atomic force microspectroscopy, X-ray diffraction, ultraviolet–visible absorption, and photoluminescence spectroscopy were used to investigate the properties of the nanoparticles and thin films. The In2O3 nanoparticles were cubic-phased spheres with a diameter of ~8 nm; their spectra exhibited a broad emission peak centered at 348 nm. The In2O3–SnO2 nanocomposites were co-particles composed of smaller In2O3 particles and larger SnO2 particles; their spectra exhibited a broad emission peak at 355 nm. After the In2O3–SnO2 nanocomposites were calcined at 400°C, the obtained thin films were highly transparent and conductive, with a thickness of 30–40 nm; the surfaces of the thin films were smooth and crack-free.

Highly sensitive and humidity-independent ethanol sensors based on In2O3 nanoflower/SnO2 nanoparticle composites

As an ethanol sensing material, the composites of In2O3–SnO2 were composed of In2O3 microflowers and SnO2 nanoparticles.

Phase Stability and Optoelectronic Properties of the Bixbyite Phase in the Gallium–Indium–Tin–Oxide System

X‐ray diffraction techniques were used to determine the phase boundaries of the In2O3 solid solution phase in the Ga2O3–In2O3–SnO2 ternary system. The effects of Ga and Sn content on the unit cell dimensions of the bixbyite phase were calculated by a linear regression fit, the results of which indicate the two substitutive cations have opposite and independent effects on the lattice parameter. These results suggest that the cations do not strongly interact with each other in the crystal. Measurements of optoelectronic properties were also taken on single‐phase bulk specimens within the solid solution to establish their dependence on composition. As anticipated, Sn doping yields corresponding increases in conductivity, reduction in the absolute value of Seebeck coefficient, and increase in optical band gap. In contrast, these properties are not significantly affected by varying Ga content, confirming that Ga behaves as an isovalent dopant at the low doping levels involved.

Plannar light source using a phosphor screen with single-walled carbon nanotubes as field emitters.

We developed and successfully fabricated a plannar light source device using a phosphor screen with single-walled carbon nanotubes (SWCNTs) as field emitters in a simple diode structure composed of the cathode containing the highly purified and crystalline SWCNTs dispersed into an organic In2O3-SnO2 precursor solution and a non-ionic surfactant. The cathode was activated by scratching process with sandpaper to obtain a large field emission current with low power consumption. The nicks by scratching were treated with Fourier analysis to determine the periodicity of the surface morphology and designed with controlling the count number of sandpapers. The anode, on the other hand, was made with phosphor deliberately optimized by coverage of ITO nanoparticles and assembled together with the cathode by the new stable assembling process resulting to stand-alone flat plane-emission panel. The device in a diode structure has a low driving voltage and good brightness homogeneity in that plane. Furthermore, field emission current fluctuation, which is an important factor in comparing luminance devices too, has a good stability in a simple diode panel. The flat plane-emission device employing the highly purified and crystalline SWCNTs has the potential to provide a new approach to lighting in our life style.

Trimethylamine sensors with enhanced anti-humidity ability fabricated from La0.7Sr0.3FeO3 coated In2O3–SnO2 composite nanofibers

In2O3–SnO2 composite nanofibers are synthesized via an electrospinning method and coated with La0.7Sr0.3FeO3 nanoparticles. Trimethylamine sensors are fabricated from the coated nanofibers and investigated at various conditions of different humidity. High response and short response/recovery times are obtained at 80°C. The response is around 8.1 to 1ppm trimethylamine, and the response and recovery times are about 1 and 6s, respectively. Especially, the sensors show good humidity-resistant ability. The response only decreases to 6.3 for 1ppm trimethylamine at 85% RH (25°C). These characteristics would make the sensors good candidates for trimethylamine detection in practical applications.

Indium–tin nanoscaled oxides synthesized under hydrothermal supercritical and postannealing pathway: Phase dynamics and characterization

With the aim of synthesizing the mixed nanoparticle system xIn2O3–(1−x)SnO2 over all molar concentration range 0 ≤ x ≤ 1, Δx = 0.1, we performed hydrothermal supercritical experiments on indium–tin hydrogel resulted from InCl3–SnCl4 water solution. Nanophases isostructural with InOOH and SnO2 were obtained by hydrothermal reaction at 400 °C, in the molar concentration range of 0.1 ≤ x ≤ 0.7; at x = 0.8 and x = 0.9 only one phase, isostructural with InOOH, was observed. Samples calcined at 500 °C with x in the range of 0.2 ≤ x ≤ 0.7 contain a nanoscaled phase isostructural with rhombohedral In2O3 and a second one isostructural with tetrahedral SnO2. At x = 0.8 and x = 0.9 only one phase isostructural with rhombohedral In2O3 appears: rhombohedral ITO phase. The determined band gap energies could recommend the rhombohedral ITO structure for visible light photocatalytic applications. The phase dynamics together with the concentration range for existence of the solid solutions in the InOOH–SnO2 and In2O3–SnO2 composite semiconducting nanoparticle systems have been evidenced and discussed.

Properties of a field emission lighting plane employing highly crystalline single-walled carbon nanotubes fabricated by simple processes

We developed a new cathode for a visible ray flat plane-emission device formed from a mixture of highly crystalline single-walled carbon nanotubes (SWNTs) dispersed into an organic In2O3–SnO2 precursor solution and a non-ionic surfactant. A thin film field emission cathode having highly homogeneously dispersed SWNTs was able to be fabricated with low driving voltage, high electron emission homogeneity in the plane, and high brightness efficiency by employing a simple scratching process for the film.The turn-on field of a diode using the optimized cathode was 1.2V/μm, with the brightness homogeneity in that plane being within 5% against the averaged brightness in the lighting plane. Favorable brightness homogeneity from the lighting device to control the content of SWNTs in the coated film was achieved by employing highly crystalline SWNTs. Furthermore, brightness efficiency and emission life-time, which are important factors when comparing luminance devices, totaled more than 70lm/W and over 5000h until reaching the half time against the initial field emission current density.This flat plane-emission device has the potential to provide a new approach to lighting in everyday life as it contributes to energy saving through its low power consumption.

High-Performance Thin Film Transistor with Amorphous In2O3–SnO2–ZnO Channel Layer

We have developed a high-mobility and high-processability oxide semiconductor using amorphous In2O3–SnO2–ZnO (a-ITZO) as the channel material. An a-ITZO thin-film transistor (TFT) was fabricated by a back-channel-etch process. Its field effect mobility was more than 20 cm2 V-1 s-1 and its subthreshold swing was 0.4 V s-1, which makes it a promising candidate for next-generation TFTs.

High-Performance Thin Film Transistor with Amorphous In2O3–SnO2–ZnO Channel Layer

High-Performance Thin Film Transistor with Amorphous In₂O₃–SnO₂–ZnO Channel Layer

Improvement of the open circuit voltage by modifying the transparent indium–tin oxide front electrode in amorphous n–i–p solar cells

ABSTRACTAt the front contact of thin film silicon solar cells, the junction between the p‐doped window layer and the n‐type transparent electrode results in a barrier that must be surmounted by the charge carriers. The barrier height is governed by the work‐function difference of these two materials. For different compositions of the well known In2O3–SnO2 (ITO) system, we find that higher oxygen partial pressure during sputter deposition increases the work function of the deposited films. Over the same range of oxygen partial pressures, ITO electrodes with low tin content applied to n–i–p type thin film silicon solar yield a gain in VOC by up to 40 mV. Copyright © 2011 John Wiley & Sons, Ltd.

Multi Junction Solar Cells Stacked with Transparent and Conductive Adhesive

We propose a polyimide transparent adhesive layer dispersed with In2O3–SnO2 (ITO) conductive particles (polyimide-ITO) to be used in the mechanical stacking of solar cells. A 20-µm-thick polyimide-ITO layer had a high transmissivity from 78 to 80% for wavelengths ranging from 500 to 1000 nm and a low connecting resistivity of 2.3 Ω cm2 at minimum. The fabrication of stacked cell consisting of a top hydrogenated amorphous silicon (a-Si:H) p–i–n cell and a bottom hetero-junction with an intrinsic thin-layer (HIT)-type silicon cell was demonstrated using an intermediate polyimide-ITO layer. A high open circuit voltage of 1.34 V was experimentally obtained. Simultaneous electric power generation from the top and bottom solar cells was achieved.

Highly porous metal oxide polycrystalline nanowire films with superior performance in gas sensors

In this work, we report for the first time a simple two-step route to fabricate a novel porous metal oxide film composed of polycrystalline nanowires with ultra-small nanoparticles, good interconnectivity between nanoparticles, and a high density of ultra-fine nanopores. The as-prepared metal oxide films combine the advantages of small crystal size, high surface-to-volume ratio, and one-dimensional-nanowire-induced unique charge transport paths (with correspondingly high interconnectivity). Taking In2O3 as an example, porous In2O3 films, composed of polycrystalline In2O3 nanowires with ultra-small nanocrystals (less than 10 nm) and a high density of ultra-fine nanopores (1.6–3.1 nm), have shown very high sensitivity and good reproducibility towards ethanol gas, which are 10–20 times higher than for In2O3 octahedra and commercial SnO2 thick films. The response/recovery speeds of the as-prepared porous In2O3 films are also 5–6 times higher than for In2O3 octahedra, SnO2 nanobelts, and commercial SnO2 thick films. We believe that such metal oxide flexible films made from highly porous nanowires will replace their traditional thick film counterparts, not only in gas sensors but also in other functional devices, such as batteries, supercapacitors, solar cells, etc.