Printed electronics

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. Some researchers expect printed electronics 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.^[1]

The term printed electronics is often related^{[by whom?]} to organic electronics or plastic electronics, in which one or more inks are composed of carbon-based compounds.^{[2][need quotation to verify]} These other terms refer to the ink material, which can be deposited by solution-based, vacuum-based, or other processes. Printed electronics, in contrast, specifies the process, and, subject to the specific requirements of the printing process selected, can utilize any solution-based material. This includes organic semiconductors, inorganic semiconductors, metallic conductors, nanoparticles, and nanotubes. The solution usually consist of filler materials dispersed in a suitable solvent. The most commonly used solvents include ethanol, xylene, Dimethylformamide (DMF),Dimethyl sulfoxide (DMSO), toluene and water, whereas, the most common conductive fillers include silver nanoparticles, silver flakes, carbon black, graphene, carbon nanotubes, conductive polymers (such as polyaniline and polypyrrole), and metal powders (such as copper or nickel). Considering the environmental impacts of the organic solvents, researchers are now focused on developing printable iks using water.^[3][4][5]

For the preparation of printed electronics nearly all industrial printing methods are employed. Similar to conventional printing, printed electronics applies ink layers one atop another.^[6] So the coherent development of printing methods and ink materials are the field's essential tasks.^[7]

The most important benefit of printing is low-cost volume fabrication.^{[citation needed]} The lower cost enables use in more applications.^[8] An example is RFID-systems, which enable contactless identification in trade and transport. In some domains, such as light-emitting diodes printing does not impact performance.^[6] Printing on flexible substrates allows electronics to be placed on curved surfaces, for example: printing solar cells on vehicle roofs. More typically, conventional semiconductors justify their much higher costs by providing much higher performance.