Indium tin oxide (ITO) is a ternary composition of indium, tin and oxygen in varying proportions. Depending on the oxygen content, it can either be described as a ceramic or alloy. Indium tin oxide is typically encountered as an oxygen-saturated composition with a formulation of 74% In, 18% O2, and 8% Sn by weight. Oxygen-saturated compositions are so typical, that unsaturated compositions are termed oxygen-deficient ITO. It is transparent and colorless in thin layers, while in bulk form it is yellowish to grey. In the infrared region of the spectrum it acts as a metal-like mirror.
Indium tin oxide is one of the most widely used transparent conducting oxides because of its two main properties: its electrical conductivity and optical transparency, as well as the ease with which it can be deposited as a thin film. As with all transparent conducting films, a compromise must be made between conductivity and transparency, since increasing the thickness and increasing the concentration of charge carriers increases the material's conductivity, but decreases its transparency.
Thin films of indium tin oxide are most commonly deposited on surfaces by physical vapor deposition. Often used is electron beam evaporation, or a range of sputter deposition techniques.
ITO is a mixed oxide of indium and tin with a melting point in the range 1526–1926 °C (1800–2200 K, 2800–3500 °F), depending on composition. The most commonly used material has a composition of ca In4Sn. The material is a n-type semiconductor with a large bandgap of around 4 eV. ITO is both transparent to visible light and has a relatively high electrical conductivity. These properties are utilized to great advantage in touch-screen applications such as mobile phones.
Indium tin oxide (ITO) is an optoelectronic material that is applied widely in both research and industry. ITO can be used for many applications, such as flat-panel displays, smart windows, polymer-based electronics, thin film photovoltaics, glass doors of supermarket freezers, and architectural windows. Moreover, ITO thin films for glass substrates can be helpful for glass windows to conserve energy.
ITO green tapes are utilized for the production of lamps that are electroluminescent, functional, and fully flexible.Also, ITO thin films are used primarily to serve as coatings that are anti-reflective and for liquid crystal displays (LCDs) and electroluminescence, where the thin films are used as conducting, transparent electrodes.
ITO is often used to make transparent conductive coating for displays such as liquid crystal displays, flat panel displays, plasma displays, touch panels, and electronic ink applications. Thin films of ITO are also used in organic light-emitting diodes, solar cells, antistatic coatings and EMI shieldings. In organic light-emitting diodes, ITO is used as the anode (hole injection layer).
ITO films deposited on windshields are used for defrosting aircraft windshields. The heat is generated by applying voltage across the film.
ITO is also used for various optical coatings, most notably infrared-reflecting coatings (hot mirrors) for automotive, and sodium vapor lamp glasses. Other uses include gas sensors, antireflection coatings, electrowetting on dielectrics, and Bragg reflectors for VCSEL lasers. ITO is also used as the IR reflector for low-e window panes. ITO was also used as a sensor coating in the later Kodak DCS cameras, starting with the Kodak DCS 520, as a means of increasing blue channel response.
ITO thin film strain gauges can operate at temperatures up to 1400 °C and can be used in harsh environments, such as gas turbines, jet engines, and rocket engines.
Because of high cost and limited supply of indium, the fragility and lack of flexibility of ITO layers, and the costly layer deposition requiring vacuum, alternative methods of preparing ITO and alternative materials are being investigated.
Alternative materials can also be used. Several transition metal dopants in indium oxide, particularly molybdenum, give much higher electron mobility and conductivity than obtained with tin.Doped binary compounds such as aluminum-doped zinc oxide (AZO) and indium-doped cadmium oxide have been proposed as alternative materials. Other, inorganic alternatives include aluminum, gallium or indium-doped zinc oxide (AZO, GZO or IZO).
Carbon nanotube conductive coatings are a prospective replacement.
As another carbon-based alternative, films of graphene are flexible and have been shown to allow 90% transparency with a lower electrical resistance than standard ITO.Thin metal films are also seen as a potential replacement material. A hybrid material alternative currently being tested is an electrode made of silver nanowires and covered with graphene. The advantages to such materials include maintaining transparency while simultaneously being electrically conductive and flexible.
Inherently conductive polymers (ICPs) are also being developed for some ITO applications.Typically the conductivity is lower for conducting polymers, such as polyaniline and PEDOT:PSS, than inorganic materials, but they are more flexible, less expensive and more environmentally friendly in processing and manufacture.
In order to reduce indium content, decrease processing difficulty, and improve electrical homogeneity, amorphous transparent conducting oxides have been developed. One such material, amorphous indium-zinc-oxide maintains short-range order even though crystallization is disrupted by the difference in the ratio of oxygen to metal atoms between In2O3 and ZnO. Indium-zinc-oxide has some comparable properties to ITO. °C, which allows for important processing steps common in organic solar cells. The improvement in homogeneity significantly enhances the usability of the material in the case of organic solar cells. Areas of poor electrode performance in organic solar cells render a percentage of the cell's area unusable.The amorphous structure remains stable even up to 500
ITO has been popularly used as a high-quality flexible substrate to produce flexible electronics.However, this substrate's flexibility decreases as its conductivity improves. Previous research have indicated that the mechanical properties of ITO can be improved through increasing the degree of crystallinity. Doping with silver (Ag) can improve this property, but results in a loss of transparency. An improved method that embeds Ag nanoparticles (AgNPs) instead of homogeneously to create a hybrid ITO has proven to be effective in compensating for the decrease in transparency. The hybrid ITO consists of domains in one orientation grown on the AgNPs and a matrix of the other orientation. The domains are stronger than the matrix and function as barriers to crack propagation, significantly increasing the flexibility. The change in resistivity with increased bending significantly decreases in the hybrid ITO compared with homogenous ITO.
ITO is typically deposited through expensive and energy-intensive processes that deal with physical vapor deposition (PVD). Such processes include sputtering, which results in the formation of brittle layers.[ citation needed ] An alternative process that uses a particle-based technique, is known as the tape casting process. Because it is a particle-based technique, the ITO nano-particles are dispersed first, then placed in organic solvents for stability. Benzyl phthalate plasticizer and polyvinyl butyral binder have been shown to be helpful in preparing nanoparticle slurries. Once the tape casting process has been carried out, the characterization of the green ITO tapes showed that optimal transmission went up to about 75%, with a lower bound on the electrical resistance of 2 Ω·cm.
Using ITO nanoparticles imposes a limit on the choice of substrate, owing to the high temperature required for sintering. As an alternative starting material, In-Sn alloy nanoparticles allow for a more diverse range of possible substrates.A continuous conductive In-Sn alloy film is formed firstly, followed by oxidation to bring transparency. This two step process involves thermal annealing, which requires special atmosphere control and increased processing time. Because metal nanoparticles can be converted easily into a conductive metal film under the treatment of laser, laser sintering is applied to achieve products' homogeneous morphology. Laser sintering is also easy and less costly to use since it can be performed in air.
For example, using conventional methods but varying the ambient gas conditions to improve the optoelectronic propertiesas, for example, oxygen plays a major role in the properties of ITO.
There has been numerical modeling of plasmonic metallic nanostructures have shown great potential as a method of light management in thin-film nanodisc-patterned hydrogenated amorphous silicon (a-Si:H) solar photovoltaic (PV) cells. A problem that arises for plasmonic-enhanced PV devices is the requirement for 'ultra-thin' transparent conducting oxides (TCOs) with high transmittance and low enough resistivity to be used as device top contacts/electrodes. Unfortunately, most work on TCOs is on relatively thick layers and the few reported cases of thin TCO showed a marked decrease in conductivity. To overcome this it is possible to first grow a thick layer and then chemically shave it down to obtain a thin layer that is whole and highly conductive.
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The main concern about ITO is the cost. ITO can be priced several times more highly than aluminium zinc oxide (AZO). AZO is a common choice of transparent conducting oxide (TCO) because of cost and relatively good optical transmission performance in the solar spectrum. However, ITO does consistently defeat AZO in almost every performance category including chemical resistance to moisture. ITO is not affected by moisture, and it can survive in a copper indium gallium selenide solar cell for 25–30 years on a rooftop.
While the sputtering target or evaporative material that is used to deposit the ITO is significantly more costly than AZO, the amount of material placed on each cell is quite small. Therefore, the cost penalty per cell is quite small too.
The primary advantage of ITO compared to AZO as a transparent conductor for LCDs is that ITO can be precisely etched into fine patterns.AZO cannot be etched as precisely: It is so sensitive to acid that it tends to get over-etched by an acid treatment.
Another benefit of ITO compared to AZO is that if moisture does penetrate, ITO will degrade less than AZO.
The role of ITO glass as a cell culture substrate can be extended easily, which opens up new opportunities for studies on growing cells involving electron microscopy and correlative light.
ITO can be used in nanotechnology to provide a path to a new generation of solar cells. Solar cells made with these devices have the potential to provide low-cost, ultra-lightweight, and flexible cells with a wide range of applications. Because of the nanoscale dimensions of the nanorods, quantum-size effects influence their optical properties. By tailoring the size of the rods, they can be made to absorb light within a specific narrow band of colors. By stacking several cells with different sized rods, a broad range of wavelengths across the solar spectrum can be collected and converted to energy. Moreover, the nanoscale volume of the rods leads to a significant reduction in the amount of semiconductor material needed compared to a conventional cell.
Inhalation of indium tin oxide may cause mild irritation to the respiratory tracts and should be avoided. If exposure is long-term, symptoms may become chronic and result in benign pneumoconiosis. Studies with animals indicate that indium tin oxide is toxic when ingested, along with negative effects on the kidney, lung, and heart.
During the process of mining, production and reclamation, workers are potentially exposed to indium, especially in countries such as China, Japan, the Republic of Korea, and Canadaand face the possibility of pulmonary alveolar proteinosis, pulmonary fibrosis, emphysema, and granulomas. Workers in the US, China, and Japan have been diagnosed with cholesterol clefts under indium exposure. Silver nanoparticles existed in improved ITOs have been found in vitro to penetrate through both intact and breached skin into the epidermal layer. Un-sintered ITOs are suspected of induce T-cell-mediated sensitization: on an intradermal exposure study, a concentration of 5% uITO resulted in lymphocyte proliferation in mice including the number increase of cells through a 10-day period.
A new occupational problem called indium lung disease was developed through contact with indium-containing dusts. The first patient is a worker associated with wet surface grinding of ITO who suffered from interstitial pneumonia: his lung was filled with ITO related particles.These particles can also induce cytokine production and macrophage dysfunction. Sintered ITOs particles alone can cause phagocytic dysfunction but not cytokine release in macrophage cells; however, they can intrigue a pro-inflammatory cytokine response in pulmonary epithelial cells. Unlike uITO, they can also bring endotoxin to workers handling the wet process if in contact with endotoxin-containing liquids. This can be attributed to the fact that sITOs have larger diameter and smaller surface area, and that this change after the sintering process can cause cytotoxicity.
Because of these issues, alternatives to ITO have been found.
The etching water used in the process of sintering ITO can only be used for a limited numbers of times before disposed. After degradation, the waste water should still contain valuable metals such as In, Cu as secondary resource as well as Mo, Cu, Al, Sn and In which can pose a health hazard to human beings.
Organic electronics is a field of materials science concerning the design, synthesis, characterization, and application of organic small molecules or polymers that show desirable electronic properties such as conductivity. Unlike conventional inorganic conductors and semiconductors, organic electronic materials are constructed from organic (carbon-based) small molecules or polymers using synthetic strategies developed in the context of organic and polymer chemistry. One of the promised benefits of organic electronics is their potential low cost compared to traditional inorganic electronics. Attractive properties of polymeric conductors include their electrical conductivity that can be varied by the concentrations of dopants. Relative to metals, they have mechanical flexibility. Some have high thermal stability.
Conductive polymers or, more precisely, intrinsically conducting polymers (ICPs) are organic polymers that conduct electricity. Such compounds may have metallic conductivity or can be semiconductors. The biggest advantage of conductive polymers is their processability, mainly by dispersion. Conductive polymers are generally not thermoplastics, i.e., they are not thermoformable. But, like insulating polymers, they are organic materials. They can offer high electrical conductivity but do not show similar mechanical properties to other commercially available polymers. The electrical properties can be fine-tuned using the methods of organic synthesis and by advanced dispersion techniques.
Organic semiconductors are solids whose building blocks are pi-bonded molecules or polymers made up by carbon and hydrogen atoms and – at times – heteroatoms such as nitrogen, sulfur and oxygen. They exist in form of molecular crystals or amorphous thin films. In general, they are electrical insulators, but become semiconducting when charges are either injected from appropriate electrodes, upon doping or by photoexcitation.
Nanoparticle are particles between 1 and 100 nanometres (nm) in size with a surrounding interfacial layer. The interfacial layer is an integral part of nanoscale matter, fundamentally affecting all of its properties. The interfacial layer typically consists of ions, inorganic and organic molecules. Organic molecules coating inorganic nanoparticles are known as stabilizers, capping and surface ligands, or passivating agents. In nanotechnology, a particle is defined as a small object that behaves as a whole unit with respect to its transport and properties. Particles are further classified according to diameter.
A dye-sensitized solar cell is a low-cost solar cell belonging to the group of thin film solar cells. It is based on a semiconductor formed between a photo-sensitized anode and an electrolyte, a photoelectrochemical system. The modern version of a dye solar cell, also known as the Grätzel cell, was originally co-invented in 1988 by Brian O'Regan and Michael Grätzel at UC Berkeley and this work was later developed by the aforementioned scientists at the École Polytechnique Fédérale de Lausanne until the publication of the first high efficiency DSSC in 1991. Michael Grätzel has been awarded the 2010 Millennium Technology Prize for this invention.
PEDOT:PSS or poly(3,4-ethylenedioxythiophene) polystyrene sulfonate is a polymer mixture of two ionomers. One component in this mixture is made up of sodium polystyrene sulfonate which is a sulfonated polystyrene. Part of the sulfonyl groups are deprotonated and carry a negative charge. The other component poly(3,4-ethylenedioxythiophene) or PEDOT is a conjugated polymer and carries positive charges and is based on polythiophene. Together the charged macromolecules form a macromolecular salt.
Hybrid solar cells combine advantages of both organic and inorganic semiconductors. Hybrid photovoltaics have organic materials that consist of conjugated polymers that absorb light as the donor and transport holes. Inorganic materials in hybrid cells are used as the acceptor and electron transporter in the structure. The hybrid photovoltaic devices have a potential for not only low-cost by roll-to-roll processing but also for scalable solar power conversion.
Indium(III) oxide (In2O3) is a chemical compound, an amphoteric oxide of indium.
Rhodium(III) oxide (or Rhodium sesquioxide) is the inorganic compound with the formula Rh2O3. It is a gray solid that is insoluble in ordinary solvents.
Printed electronics is a set of printing methods used to create electrical devices on various substrates. Printing typically uses common printing equipment suitable for defining patterns on material, such as screen printing, flexography, gravure, offset lithography, and inkjet. By electronic industry standards, these are low cost processes. Electrically functional electronic or optical inks are deposited on the substrate, creating active or passive devices, such as thin film transistors; capacitors; coils; resistors. Printed electronics is expected to facilitate widespread, very low-cost, low-performance electronics for applications such as flexible displays, smart labels, decorative and animated posters, and active clothing that do not require high performance.
Organic photovoltaic devices (OPVs) are fabricated from thin films of organic semiconductors, such as polymers and small-molecule compounds, and are typically on the order of 100 nm thick. Because polymer based OPVs can be made using a coating process such as spin coating or inkjet printing, they are an attractive option for inexpensively covering large areas as well as flexible plastic surfaces. A promising low cost alternative to conventional solar cells made of crystalline silicon, there is a large amount of research being dedicated throughout industry and academia towards developing OPVs and increasing their power conversion efficiency.
Ultrasonic nozzles are a type of spray nozzle that uses high frequency vibration produced by piezoelectric transducers acting upon the nozzle tip that will create capillary waves in a liquid film. Once the amplitude of the capillary waves reaches a critical height, they become too tall to support themselves and tiny droplets fall off the tip of each wave resulting in atomization.
An organic solar cell (OSC) or plastic solar cell is a type of photovoltaic that uses organic electronics, a branch of electronics that deals with conductive organic polymers or small organic molecules, for light absorption and charge transport to produce electricity from sunlight by the photovoltaic effect. Most organic photovoltaic cells are polymer solar cells.
A copper indium gallium selenide solar cell is a thin-film solar cell used to convert sunlight into electric power. It is manufactured by depositing a thin layer of copper, indium, gallium and selenium on glass or plastic backing, along with electrodes on the front and back to collect current. Because the material has a high absorption coefficient and strongly absorbs sunlight, a much thinner film is required than of other semiconductor materials.
Transparent conducting films (TCFs) are thin films of optically transparent and electrically conductive material. They are an important component in a number of electronic devices including liquid-crystal displays, OLEDs, touchscreens and photovoltaics. While indium tin oxide (ITO) is the most widely used, alternatives include wider-spectrum transparent conductive oxides (TCOs), conductive polymers, metal grids and random metallic networks, carbon nanotubes (CNT), graphene, nanowire meshes and ultra thin metal films.
Nanoarchitectures for lithium-ion batteries are attempts to employ nanotechnology to improve the design of lithium-ion batteries. Research in lithium-ion batteries focuses on improving energy density, power density, safety, durability and cost.
There are currently many research groups active in the field of photovoltaics in universities and research institutions around the world. This research can be categorized into three areas: making current technology solar cells cheaper and/or more efficient to effectively compete with other energy sources; developing new technologies based on new solar cell architectural designs; and developing new materials to serve as more efficient energy converters from light energy into electric current or light absorbers and charge carriers.
As with any material implanted in the body, it is important to minimize or eliminate foreign body response and maximize effectual integration. Neural implants have the potential to increase the quality of life for patients with such disabilities as Alzheimer's, Parkinson's, epilepsy, depression, and migraines. With the complexity of interfaces between a neural implant and brain tissue, adverse reactions such as fibrous tissue encapsulation that hinder the functionality, occur. Surface modifications to these implants can help improve the tissue-implant interface, increasing the lifetime and effectiveness of the implant.
Indium acetylacetonate, also known as In(acac)3, is a compound with formula In(C5H7O2)3. It is the indium complex of acetylacetone.
A chemiresistor is a material that changes its electrical resistance in response to changes in the nearby chemical environment. Chemiresistors are a class of chemical sensors that rely on the direct chemical interaction between the sensing material and the analyte. The sensing material and the analyte can interact by covalent bonding, hydrogen bonding, or molecular recognition. Several different materials have chemiresistor properties: metal-oxide semiconductors, some conductive polymers, and nanomaterials like graphene, carbon nanotubes and nanoparticles. Typically these materials are used as partially selective sensors in devices like electronic tongues or electronic noses.