Preparation of indium tin oxide targets with a high density and single phase structure by normal pressure sintering process

The present work mainly describes the technology for preparing indium-tin oxide （ITO） targets by cold isostatic pressing （CIP） and normal pressure sintering process. ITO powders were produced by chemical co-precipitation and shaped into an ITO green compact with a relative density of 60% by CIP under 300 MPa. Then, an ITO target with a relative density larger than 99.6% was obtained by sintering this green compact at 1550℃ for 8 h. The effects of forming pressure, sintering temperature and sintering time on the density of the target were inves- tigated. Also, a discussion was made on the sintering atmosphere.

Preparation of Indium Tin Oxide Films on Polycarbonate substrates by Radio-frequency Magnetron Sputtering

Indium tin oxide（ITO）thin films（100±10nm）were deposited on PC（polycarbonate）and glass substrates by rf（radio-frequency）mannetron spuutering.The oxygen content of the ITO films was changed by variation of the sputtering gas composition.All the other deposition parameters were kept constant.The sheet resistance.optical transmittance and microstructure of ITO films were investigated using a four-point probe.spectrophotometer,X-ray diffractometer（XRD）and atomic force microscope（AFM）.Sheet resistances for the ITO films with optical transmittance more than 75% on PC substrates varied from 40Ω/cm^2 to more than 104 Ω/cm^2 with increasing oxygen partial pressure from O to about 2%.The same tendeney of sheet resistances increasing with increasing oxygen partial pressure was observed on glass substrates.The X-ray diffraction data indicated polycrystalline filns with grain orientations predominantly along（440）and （422）directions.The intensities of （440）and （422）peaks increased slightly with the increase of oxygen partial pressure both on PC and glass substrates.The AFM images show that the ITO films on PC substrates were dense and uniform.The average grain size of the films was about 40nm.

Electrical and optical properties of indium tin oxide/epoxy composite film

The electrical and optical properties of the indium tin oxide （ITO）/epoxy composite exhibit dramatic variations as functions of the ITO composition and ITO particle size. Sharp increases in the conductivity in the vicinity of a critical volume fraction have been found within the framework of percolation theory. A conductive and insulating transition model is extracted by the ITO particle network in the SEM image, and verified by the resistivity dependence on the temperature. The dependence of the optical transmittance on the particle size was studied. Further decreasing the ITO particle size could further improve the percolation threshold and light transparency of the composite film.

Synthesis and sintering of indium tin oxide nanoparticles by citrate-nitrate combustion method

Spherical indium tin oxide （ITO） nanoparticles were synthesized by combustion method using citric acid as fuel and nitrates as oxidizer. The obtained ITO nanoparticles were characterized by TG-DSC, FT-IR, XRD, BET, TEM, and SEM. The ITO nanoparticles grew steadily with the increase of heat treatment temperature, and the 700~C calcined particles had a crystallite size of 25.3 nm and a specific surface area of 26.1 m2.g i The avoidance of chlorine ions in the synthesis process decreases particle agglomeration and promotes powder densification. The 900~C sintered pellet had a density of 67.6% of theoretical density （TD） and increased steadily to 97.3% for the 1400℃ sintered ceramics, respectively.

Effect of Sn^(4+) content on properties of indium tin oxide nanopowders

Indium tin oxide(ITO)nanopowders were prepared by a modified chemical co-precipitation process.The influence of different SnO2 contents on the decomposition behavior of ITO precursors,and on the phase and morphology of ITO precursors and ITO nanopowders were studied by X-ray diffractometry,transmission electron microscopy and differential thermal and thermogravimetry analysis methods.The TG-DSC curves show that the decomposition process of precursor precipitation is completed when the temperature is close to 600 ℃and the end temperature of decompositionis somewhat lower when the doping amount of SnO2 is increased.The XRD patterns indicate that the solubility limit of Sn4+ relates directly to the calcining temperature. When being calcined at 700℃,a single phase ITO powder with 15%SnO2(mass fraction)can be obtained.But,when the calcining temperature is higher than 800℃,the phase of SnO2 will appear in ITO nanopowders which contain more than 10%SnO2.The particle size of the ITO nanopowders is 15-25 nm.The ITO nanoparticles without Sn have a spherical shape,but their morphology moves towards an irregular shape when being doped with Sn4+.

Microstructure Study on Nano-phase Powder of Indium Tin Oxide

hemical co-precipitation method was used to prepare indium tin hydroxide. Indium tin hydroxide has the structure of cubic crystal. The cubic crystal structure transformed to amorphous after heat treatment at 250℃ for 1 h. When the heat treatment temperature was higher than 280℃, the amorphous transformed to cubic crystal structure. After heat treatment at 600℃ for 1 h, the particle size of indium tin oxide is 8～20 nm. The weight ratio of In∶Sn is near 9∶1. Its granule has spherical shape. The dispersity is good.

Enhanced performance in organic photovoltaic devices with a KMnO_4 solution treated indium tin oxide anode modification

The properties of poly（3-hexylthiophene）：（6,6）-phenyl C61 butyric acid methyl ester （P3HT：PCBM） organic pho- tovoltaic devices （OPVs） with an indium tin oxide （ITO） anode treated by a KMnO4 solution are investigated. The optimized KMnO4 solution has a concentration of 50 rag/L, and ITO is treated for 15 min. The modification of ITO anode results in an enhancement of the power conversion efficiency （PCE） of the device, which is responsible for the increase of the photocurrent. The performance enhancement is attributed to the work function modification of the ITO substrate through the strong oxygenation of KMnO4, and then the charge collection efficiency is improved.

Work Function Enhancement of Indium Tin Oxide via Oxygen Plasma Immersion Ion Implantation

Indium tin oxide （ITO） transparent conducting film was treated with oxygen plasma immersion ion implantation （PIII）. X-ray photoelectron spectroscopy （XPS） was employed to characterize the effect. The results suggested that the oxygen content in the surface was increased and maintained for more than 50 h compared with traditional plasma-treated samples. Meanwhile, the work function of ITO estimated by comparing the peak shift in the XPS diagram suggested a corresponding increase by more than 1 eV.

Improvement of the light output and contact resistance of InGaN-based light-emitting diodes based on tantalum-doped indium tin oxide as p-type electrodes

This paper reports that highly transparent and low resistance tantalum-doped indium tin oxide （Ta-doped ITO） films contacted to p-type GaN have been prepared by the electron-beam evaporation technique. The Ta-doped ITO contacts become Ohmic with a specific contact resistance of $／sim 5.65／times 10^{ - 5}$$／Omega ／cdot$cm$^{2}$ and show the transmittance of $／sim $98% at a wavelength of 440nm when annealed at 500／du. Blue light emitting diodes （LEDs） fabricated with Ta-doped ITO p-type Ohmic contact layers give a forward-bias voltage of 3.21V at an injection current of 20mA. It further shows that the output power of LEDs with Ta-doped ITO contacts is enhanced 62% at 20mA in comparison with that of LEDs with conventional Ni/Au contacts

Fabrication and Properties of DC Magnetron Sputtered Indium Tin Oxide on Flexible Plastic Substrate

Indium tin oxide （ITO） thin films deposited on flexible polyethylene terephthalate （PET） substrates at low temperature by DC magnetron sputtering from an In-Sn （90-10 wt pct） alloy target were studied. The correla- tion between deposition conditions and ITO property was systematically investigated and characterized. These as-deposited ITO films were used as the anode contact for flexible organic light-emitting diodes （FOLEDs）. The fabricated FOLEDs with a structure of PET/ITO/NPB （50 nm）/Alq （20 nm）/Mg：Ag （100 nm） showed a maximum luminance of 2125 cd/m^2 at 13 V.

Work Function Optimization Technology of Indium Tin Oxide Films

Indium tin oxide(In_(2)O_(3)∶Sn)film is one of the most potential materials in the field of semiconductor industry.However,untreated In2O3∶Sn film has a low work function which can result in a high energy barrier that hinders the passage of carriers through the interface,thus leading to poor overall performance of directly prepared devices.In this study,crystalline transparent conductive In_(2)O_(3)∶Sn films were prepared by plasma exposure assisted magnetron sputtering under room temperature.Based on multiple testing methods,it can be found that the low temperature crystallization characteristics of In_(2)O_(3)∶Sn film were enhanced and the work function was effectively improved after Ar^(+)plasma exposure.The increase of the work function of In_(2)O_(3)∶Sn film was due to the increment of Sn⁃O bond on the surface brought by the transition from low oxidation state Sn^(2+)to high oxidation state Sn^(4+)under the action of high exposure.

Enrichment by air classification of indium components from In-containing scrap powders scraped by sand-blasting chamber shields of sputter coaters

Raw scrap powders containing 10 wt.% In were recovered by sand-blasting chamber shields of sputter coaters and used as a sole source of indium components for both sieving and air-classification. Sieving was performed first as a feasibility test, and enrichment of indium component was possible up to 19 wt.% with a mesh size of 635. With this experimental basis, the raw scrap powders were air-classified into 12 lots according to the revolution per minute （r/min） of a single horizontally arranged classifying wheel： 4000, 6000, 8000, 10000, 12000, and 14000 r/rain. The particle cut size varied from 56 to 5 μm with turbo wheel speeds corresponding to 4000 to 14000 r/min, respectively, and enrichment of indium component was possible in fine overflow fractions at all turbo wheel speeds while the indium components were not concentrated in all of the coarse underflow fractions. The grade of the indium components became higher with decreasing particle size of the air-classified scrap powders, with the highest grade obtained in the fine overflow fraction with a turbo wheel speed of 14000 r/min. The amount of indium in the fine overflow fractions varied between 15.9 wt.% and 31.5 wt.%. All in all, the grade or purity of the indium component improved rather significantly from 15.9 wt.% to 31.5 wt.% by air-classification, but this also resulted in overall decrease in recovery rate from 99.33% to 49.64%. Therefore, enrichment and separation of indium should be optimized for maximum recovery and grade of the indium components, which can be used as raw materials in the subsequent electro-refining processes.

Optical transparent metamaterial structure for microwave-infrared-compatible camouflage based on indium tin oxide

A visible transparent metamaterial absorber was designed and fabricated with ultrabroadband microwave absorption and low infrared emissivity to meet the increasing demand for multispectral compatible camouflage. The absorber was fabricated with a low-infrared emissive layer at the top, a microwave-absorbing layer in the middle, and a reflective layer at the bottom, which were separated by polymethyl methacrylate plates. The absorber showed an average visible transmittance of 55%, infrared emissivity of ~0.37, and effective microwave absorption bandwidth of 32.1 GHz with a total thickness of 3.0 mm. Furthermore,microwave absorption exhibited wide-angle stability and polarization insensitivity characteristics. The mechanism of microwave attenuation was further explored through effective electromagnetic parameters as well as surface current, electric field, magnetic field, and energy loss density distributions. The experimental results were consistent with those of the simulations and calculations, indicating the potential of the designed metamaterial absorber for future applications in multispectral compatible camouflage.

Novel seed-assisted synthesis of indium tin oxide submicro-cubes and their resistivity

Indium tin oxide films,an important n-type semiconductor oxide,show great prospects in optoelectronic device applications.Consequently,as a key raw material of targets for sputtering films,it is important to prepare low-resistivity indium tin oxide powders.Herein,low-resistivity indium tin oxide submicro-cubes are synthesized by a seed-assisted coprecipitation method.The effects of seed content,In^(3+)concentration,aging time,reaction temperature and calcination temperature on resistivity were investigated by single factor and orthogonal experiments.To ensure reliability and reproducibility of data,each experiment was repeated three times and resistivity of each sample was measured three times to obtain average value.The results indicated that optimal sample was matched with cubic phase In_(2)O_(3).The single-crystal indium tin oxide particles exhibited a regular cubic shape with a size of nearly 500 nm and low resistivity of 0.814Ω·cm.Compared with particles prepared by the conventional coprecipitation method,indium tin oxide submicro-cubes showed good dispersion.The presence of seed particles provided nucleation sites with lower energy barriers and promoted formation of submicro-cubes.The face-to-face contact among particles and good dispersion contributed to electron transfer,resulting in lower resistivity.The seed-assisted synthesis provides a novel way to prepare low-resistivity indium tin oxide submicro-cubes.

Ultra-high extinction-ratio light modulation by electrically tunable metasurface using dual epsilon-near-zero resonances

The lossy nature of indium tin oxide(ITO) at epsilon-near-zero(ENZ) wavelength is used to design an electrically tunable metasurface absorber. The metasurface unit cell is constructed of a circular resonator comprising two ITO discs and a high dielectric constant perovskite barium strontium titanate(BST) film. The ENZ wavelength in the accumulation and depletion layers of ITO discs is controlled by applying a single bias voltage. The coupling of magnetic dipole resonance with the ENZ wavelength inside the accumulation layer of ITO film causes total absorption of reflected light. The reflection amplitude can achieve ~84 d B or ~99.99% modulation depth in the operation wavelength of 820 nm at a bias voltage of-2.5 V. Moreover, the metasurface is insensitive to the polarization of the incident light due to the circular design of resonators and the symmetrical design of bias connections.

Fully Printed High‑Performance n‑Type Metal Oxide Thin‑Film Transistors Utilizing Coffee‑Ring Effect

Metal oxide thin-films transistors(TFTs)produced from solution-based printing techniques can lead to large-area electronics with low cost.However,the performance of current printed devices is inferior to those from vacuum-based methods due to poor film uniformity induced by the“coffeering”effect.Here,we report a novel approach to print highperformance indium tin oxide(ITO)-based TFTs and logic inverters by taking advantage of such notorious effect.ITO has high electrical conductivity and is generally used as an electrode material.However,by reducing the film thickness down to nanometers scale,the carrier concentration of ITO can be effectively reduced to enable new applications as active channels in transistors.The ultrathin(~10-nm-thick)ITO film in the center of the coffee-ring worked as semiconducting channels,while the thick ITO ridges(>18-nm-thick)served as the contact electrodes.The fully inkjet-printed ITO TFTs exhibited a high saturation mobility of 34.9 cm2 V^(−1) s^(−1) and a low subthreshold swing of 105 mV dec^(−1).In addition,the devices exhibited excellent electrical stability under positive bias illumination stress(PBIS,ΔV_(th)=0.31 V)and negative bias illuminaiton stress(NBIS,ΔV_(th)=−0.29 V)after 10,000 s voltage bias tests.More remarkably,fully printed n-type metal–oxide–semiconductor(NMOS)inverter based on ITO TFTs exhibited an extremely high gain of 181 at a low-supply voltage of 3 V,promising for advanced electronics applications.

Sputtering under Mild Heating Enables High-Quality ITO for Efficient Semi-Transparent Perovskite Solar Cells

Semi-transparent perovskite solar cells(ST-PSCs)are promising in building-integrated photovoltaics(BIPVs)and tandem solar cells(TSCs).One of the keys to fabricate high-performance ST-PSCs is depositing efficient transparent electrodes.Indium tin oxide(ITO)is an excellent transparent conductive oxide with good light transmittance and high conductivity.However,the high sheet resistance of ITO sputtered at room temperature leads to the low fill factor(FF)and poor power conversion efficiency(PCE)of the ST-PSCs.Here,we study the effect of the sputtering temperature on the properties of ITO and the performance of ST-PSCs.We find that when the sputtering temperature increases from the room temperature to 70℃,the crystallinity of the sputtered ITO gradually improves.Therefore,the sheet resistance decreases and the corresponding device performance improves.However,once the sputtering temperature further increases over 70℃,the underlying hole transport layer will be damaged,leading to poor device performance.Therefore,the optimized mild heating temperature of 70℃is applied and we obtain ST-PSCs with a champion PCE of 15.21%.We believe this mild heating assisted sputtering method is applicable in fabricating BIPVs and TSCs.

A Cost-Effective Co-precipitation Method for Synthesizing Indium Tin Oxide Nanoparticles without Chlorine Contamination

Indium tin oxide （ITO） nanoparticles with crystallite size of 12.6 nm and specific surface area of 45.7 m 2 ·g-1 were synthesized by co-precipitation method.The indium solution was obtained by dissolving metal indium in HNO3.The tin solution was obtained by dissolving metal tin in HNO3 and followed by stabilizing with citric acid.The free of chlorine ions in the synthesis process brought several advantages：shortening the synthesis time,decreasing the particle agglomeration,decreasing the chlorine content in the ITO nanoparticles and improving the particle sinterability.This is the first time to report the synthesis of ITO nanoparticles free from chlorine contamination without using the expensive metal alkoxides as starting materials.

Influence of Annealing Temperature on the Microstructure and Electrical Properties of Indium Tin Oxide Thin Films

Indium tin oxide （ITO） thin films were prepared on alumina ceramic substrates by radio frequency magnetron sputtering. The samples were subsequently annealed in air at temperatures ranging from 500 to 1,100 ℃ for 1 h. The influences of the annealing temperature on the microstructure and electrical properties of the ITO thin films were investigated, and the results indicate that the as-deposited ITO thin films are amorphous in nature. All samples were crystallized by annealing at 500 ~C. As the annealing temperature increases, the predominant orientation shifts from （222） to （400）. The carrier concentration decreases initially and then increases when the annealing temperature rises beyond 1,000 ℃. The resistivity of the ITO thin films increases smoothly as the annealing temperature increases to just below 900 ℃. Beyond 900 ℃, however, the resistivity of the films increases sharply. The annealing temperature has a significant effect on the stability of the ITO/Pt thin film thermocouples （TFTCs）. TFTCs annealed at 1,000 ℃ show improved high- temperature stability and Seebeck coefficients of up to 77.73 pV/℃.

Electrophoretic deposition of a supercapacitor electrode of activated carbon onto an indium-tin-oxide substrate using ethyl cellulose as a binder

A transparent energy storage device is an essential component for transparent electronics.The increasing demand for high-power devices stimulates the development of transparent supercapacitors with high power density.A transparent electrode for such supercapacitors can be assembled via the electrophoretic deposition of an active material powder with a binder onto a transparent substrate.The properties of the binder critically influence the electrochemical behavior and performance of the resulting electrode.Ethyl cellulose(EC)is known as an eco-friendly,transparent,flexible,and inexpensive material.Here,we fabricated an electrode film with EC binder via electrophoretic deposition on an indium tin oxide(ITO)substrate instead of using the conventional polytetrafluoroethylene(PTFE)binder.The assembled electrodes with EC and PTFE were compared to investigate the feasibility of EC as a binder from different perspectives,including homogeneity,wettability,electrochemical behavior,and mechanical stability.The EC enabled the formation of a homogeneous film composed of smaller particles and with a higher specific capacitance compared with films prepared with PTFE.The annealing improved the adhesion strength of the EC because of its glass transition;however,its hydrophobic nature limited utilization of the active material for charge storage.Subsequent electrochemical activation improved the wettability of the electrode,resulting in an increased capacitance of 60 F g^(-1).Furthermore,even with the lower wettability of EC compared with that of PTFE,better rate performance was possible with the EC electrode.The increased mechanical stability after the annealing process ensured an excellent cycle life of 95%capacitance retention for 15,000 cycles.