Organic electronics

Organic electronics is a branch of electronics, the electronic circuits of conducting polymers or small organic compounds. It is used synonymously with the term plastic electronics, plastic electronics or polymer electronics common. The general feature of all concepts is usually the design of the circuits of macromolecules and compared to conventional electronics from multi - molecular structures of larger dimension. Therefore, also the new concept of art polytronics is used. In the English -speaking world, the term is mainly used plastics electronics.

Feature of plastic electronics is the use of microelectronic devices on substrates of organic films and with conductors and conductive components from organic molecules ( organic semiconductors ) are manufactured. Molecules ( monomers and oligomers in addition to the polymers, especially ) can be printed thereby in the form of thin films or small volume of the film, adhered or otherwise attached. For the production of thin layers into consideration any procedures that are used for electronics on ceramic or semi-conductive carriers come.

• 3.1 Special Applications

Polymer Electronics

Depending on the chemical structure of the polymers may possess electrically conductive, semiconductive or insulating properties. The insulating ability of "normal" polymers of daily use have been in the early 20th century, used in electrical engineering, for example, as an insulating sheath of cables. In the early 1970s, electrically conductive and semiconductive polymers were first prepared and characterized. For services in this area of the Nobel Prize in Chemistry to Alan Heeger J., Alan G. MacDiarmid and Hideki Shirakawa were awarded in 2000. The term was coined " plastic electronics " Through the use of these novel materials for electronic applications.

Polymer electronics is still largely in the laboratory or pilot stage. In 2008, a market-ready, printed RFID chip was presented with the PolyID. The first microprocessor from polymer films was presented by a research team in 2011.

The planned polytronic applications to develop the market for extremely low-cost ubiquitous electronics, which on the basis of specific requirements and the cost of construction and connection technology can not be achieved by the traditional silicon-based electronics. The manufacturing processes for polymer electronics are therefore developing towards high volume, extremely low manufacturing costs and largely free of construction steps. Cheap printing, roll-to -roll coating and structuring methods form an important basis for future products in this area.

Structure of the polymers

The basic structure of electronic polymers are conjugated polymer main chains, which consist of a strictly alternating sequence of single and double bonds. These polymers have characterized a delocalized electron system which semiconductor properties, and after chemical doping allows conductivity.

Advantages of polymer electronics

The main advantage of these circuits is the reduced production costs, making them ( eg RFID tags on disposable packaging as electronic price tags ) are of interest for so-called " disposable electronics ." Addition polymers have properties that are not possible with traditional semiconductors. Thus, for example, flexible films with integrated circuits manufactured.

Disadvantages of polymer electronics

There are no reliable data on the lifetime of data stored in electronic polymer assemblies. As long as the question of the expectable life there are no clear indications of any tests can be performed, and therefore the polymer electronics remains a largely academic issue. Solutions that can dispense with memory contents, are rare and have consistently low quality. If the question arises, what actionable results, has not shown the research, can feel transported back to the ancient times of the electronics in early 1960 we therefore. In hybrid structures ( combination of organic electronics with classical silicon technology), a large part of the special characteristics of polymer electronics is lost.

Small molecules

Small molecules (English: small molecules ) are currently used mainly for OLEDs ( SOLED or SMOLED ). Principle be achieved with specially constructed single molecules electronic functions such as diodes on the molecule. This technology is still in a very early stage of development and is attributed to the area of nanotechnology.

Applications

In the established applications of the information processing inorganic semiconductors have compared to molecular-based technologies, inter alia, the advantage of a much higher carrier mobility and stability in relation to environmental conditions. The aim of the development of plastic electronics therefore not included (so far) to replace the traditional semiconductor technologies based on inorganic semiconductors. The focus is rather the development of electronic applications requiring very light and / or mechanically flexible substrates.

Such applications include, for example,

• Flat screens or so-called
• " Electronic paper "

Or applications that are very inexpensive and simple fabrication method of a cost-efficient mass production presuppose such as

• Photovoltaic systems
• Smart cards
• Sensors.
• Identification badges

Such applications are problematic for the classical manufacturing and structuring technology in the semiconductor industry, as the necessary processes in extreme conditions of ultra-high vacuum, requiring great demands on process control and high temperatures - conditions that are very expensive and exclude sensitive, flexible substrates based on polymers.

Special Applications

In addition to pure conductive or semi-conductive properties, the materials of polymer electronics can also emit light under certain circumstances. This enables its use in organic light emitting diodes (OLED). The reverse effect to absorb light and convert it into electrical energy, enables the use in organic solar cells (organic photovoltaics). In addition, these polymers may be used as sensors or as an organic memory. With organic field-effect transistors ( OFET), integrated circuits can be established. Also applications as electronic paper appear to be realizable.

In principle opens up the polymer electronics, the entire field of electronics, which is so far largely influenced by silicon-based components. Because the mobility of the charge carriers with approximately 0.2 cm ² / Vs by three to four orders of magnitude lower than in silicon, extremely fast switching times with OFETs for the foreseeable future will not be realized. Applications such as high-performance microprocessors are therefore, at least in the medium to be expected.

In medical thrombosis, pulmonary embolism and stroke can be detected early with a polytroned equipped analyzer. Practically, this can be implemented, for example, with a small blood lab in your pocket, which quickly analyzes the risk of a blood clot in the legs before a long haul flight, or in a sensor bracelet which can measure electromagnetic and patients warns with pacemakers from life- threatening radiation.

Manufacturing process

In contrast, organic molecules and polymers can by comparatively simple methods at relatively low processing temperatures (<120 ° C) applied extensively to a variety of different substrates and structure in the micrometer range. Among such methods,

• Traditional printing techniques, which are transferred to the manufacture of plastic electronics (eg ink-jet printing (see also, for example ), screen printing, micro-contact printing stamp )
• Spin-coating ( spin coating ), which is combined with subsequent patterning processes such as photolithography, or embossing techniques.

These procedures assume that the conductive organic molecules present as a solution. However, only a few of these molecules possess a relevant solubility, so that in order to achieve solubility of most substances need to be chemically modified or soluble precursors are used which are converted chemically after the landfill ( precursor method).

Physical vapor deposition (PVD ) is another production possibility, however, it involves more complex in comparison with deposition techniques, such as organic vapor phase deposition ( OPVD ) or thermal evaporation, which are associated with these methods, as a structuring method usually shadow masks are used.

Functional elements

To the functional elements, which could be implemented as an active unit to a plastic electronics include:

• Organic field-effect transistor / thin film transistor (OFET / OTFT ): In many approaches to development only the semiconductor layer is composed of organic compounds ( by monomer using oligomers or with polymers) manufactured and the electrodes conventionally or, for example by means of metal transfer ram pressure of metallic substances. It can, however, also realize approaches in which all components are made of polymers.
• Organic light emitting diode (OLED), realized by means of using monomers and polymers.
• Organic solar cell realized by means of monomers and polymers using.