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BY: GUNJAN SINGHROLL NO. 7684

B.TECH(Elect. & Instr.)

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IntroductionOrganic electronics, plastic electronics or polymer electronics, is a branch of electronics that deals with conductive polymers, plastics, or small molecules. It is called 'organic' electronics because the polymers and small molecules are carbon-based, like the molecules of living things. This is as opposed to traditional electronics (or metal electronics) which relies on inorganic conductors such as copper or silicon.

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ORGANIC ELECTRONICS

Small Organic

Molecules

Plastics

Conductivepolymers

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Why switch to organic when we are already comfortable with metal

electronics?

–Could we make electronics from molecules or plastic?

-YES–What would the benefits be?

–Cheaper than silicon to produce–Flexible sheets

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Polymer: A chemical compound or mixture of compounds formed by polymerization and consisting essentially of repeating structural units

Electronics: A branch of physics that deals with the emission, behavior, and effects of electrons (as in electron tubes and transistors) and with electronic devices

In constructing a polymer electronic device we are fundamentally interested controlling the flow of energy

·Where and how it is absorbed· Where and how it flows·Where and how it is emitted

Basics Of Organic Electronics

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History Henry Letheby discovered the earliest known

organic conductive material in 1862. Using anodic oxidation of aniline in sulphuric acid, he produced a partly conductive material, that was later identified as Polyaniline. In the 1950s, the phenomenon that polycyclic aromatic compounds formed semi-conducting charge-transfer complex salts with halogens was discovered, showing that some organic compounds could be conductive as well.

 In 1987, the first organic diode device of was produced at Eastman Kodak by Ching W. Tang and Steven Van Slyke. spawning the field of organic light-emitting diodes (OLED) research and device production. For his work, Ching W. Tang is widely considered as the father of organic electronics for this work.

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FeaturesConductive polymers are lighter, more

flexible, and less expensive than inorganic conductors. This makes them a desirable alternative in many applications.

It also creates the possibility of new applications that would be impossible using copper or silicon.

Organic electronics not only includes organic semiconductors, but also dielectrics, conductors and light emitters.

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Fabrication MethodsThere are important differences between

the processing of small molecule organic semiconductors and semiconducting polymers. Small molecule semiconductors are quite often insoluble and typically require deposition via vacuum sublimation.

While usually thin films of soluble conjugated polymers. Devices based on conductive polymers can be prepared by solution processing methods. Both solution processing and vacuum based methods produce amorphous and polycrystalline films with variable degree of disorder.

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OLED

ELECTRONICS(TFT’s)

OFET

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ORGANIC ELECTRONICS

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Organic Light Emitting DiodeAn OLED (organic light-emitting diode) is a light-emitting diode (LED) in which the emissive electroluminescent layer is a film of organic compound which emits light in response to an electric current. This layer of organic semiconductor is situated between two electrodes; typically, at least one of these electrodes is transparent. OLEDs are used to create digital displays in devices such as television screens, computer monitors, portable systems such as mobile phones, handheld game consoles and PDAs.

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Organic Field Effect TransistorAn organic field-effect transistor (OFET) is a field-effect transistor using an organic semiconductor in its channel. OFETs can be prepared either by vacuum evaporation of small molecules, by solution-casting of polymers or small molecules, or by mechanical transfer of a peeled single-crystalline organic layer onto a substrate. These devices have been developed to realize low-cost, large-area electronic products and biodegradable electronics. OFETs have been fabricated with various device geometries. 

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•Advantages of organic transistors:▫Compatibility with plastic substances▫Lower temperature is used while

manufacturing (60-120°C)▫Lower cost and deposition processes such

as spin-coating, printing and evaporation

•Disadvantages of organic transistors:▫Lower mobility and switching speeds

compared to Si wafers▫Usually does not operate under invasion

mode.

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Organic Solar CellAn organic solar cell is a device that uses organic electronics to convert light into electricity. Organic solar cells utilize organic photovoltaic materials, organic semiconductor diodes that convert light into electricity.

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Organic Thin Film TransistorsTFTs are transistors created using thin films,

usually of silicon deposited on glass. The deposited silicon must be crystallized using laser pulses at high temperatures.

For organics to compete with a-S:H, their mobility should be greater than 0.1 cm²/V s.

OTFTs active layers can be thermally evaporated and deposited at much lower temperatures (i.e. 60° C)

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Benefits Does not require a

glass substrate as amorphous silicon does

Low temperature manufacture

Could be made on a piece of plastic

Deposition techniques could reduce costs dramatically

Challenges Workarounds for

complications with photoresistors

Finding organic semiconductors with high enough mobility & switching times

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18Organic Semiconductors Device-OLED

An organic light-emitting diode (OLED) is a special type of light-emitting diode (LED) in which the emissive layer comprises a thin-film of certain organic compounds. The emissive electroluminescent layer can include a polymeric substance that allows the deposition of very suitable organic compounds

For example, in rows and columns on a flat carrier by using a simple "printing" method to create a matrix of pixels which can emit different colored light.

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Organic Light Emitting Diodes:How they work??

There are several parts to an OLED: Substrate: the material the layers of the OLED are

put on Emissive layer: the layer where light is made Conductive layer Anode Cathode The emissive and conductive layers are made of

special organic molecules that conduct electricity. The anode and  the OLED to the source of electricity.

When electricity is applied to an OLED, the emissive layer becomes negatively charged and the conductive layer becomes positively charged. This causes a change in the electrical levels and makes radiation that has a frequency in the range of visible light.

OLED, as with all diodes, can only work if electricity flows through them in the correct direction. The Anode, connected to the emmisive layer must be at a higher electrical potential(more volts, more positive) than the cathode, connected to the conductive layer, for the OLED to work.

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OLED/LED: What’s the diff? Both OLED and LED use the same

principle of electroluminescence- the optical and electrical phenomenon where certain materials emit light in response to an electric current passing through it.OLED Lighter weight Perform at lower efficiencies Less power consumption Organic based chemicals

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Advantages & Disadvantages

• In some ways, OLEDs are better for display devices than LCDs. There are also ways LCDs are better.

• OLEDs can make more different colors at different levels of brightness than LEDs. Unlike LCDs their colors do not change when viewed at an angle.

• They are also much cheaper to make.• Because of backlighting and filtering, OLEDs use far less power

than LCDs for the amount of light made. • OLEDs also react faster to changes in electricity. They turn on

and off much faster than LCDs.• LEDs will last longer than OLEDs. This is the biggest problem

with OLEDs. Currently most OLEDs used in displays will work for about 5,000 hours of use. LEDs normally work for 60,000 hours.

• Organic materials that make up OLEDs are also more easily damaged by water.

• OLED technology is currently patented by the Eastman Kodak company and several other companies. Because of this, a company must pay to be allowed to use it in their product.

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Future OutlookOTFTs for active-matrix displaysFlexible view screens (or anything…)New generations of smart cards Organic smart pixels with OLEDsLarge-area display electronicsOrganic semiconductor advances in

mobility, switching time, and manufacturing may lead to many possibilities

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References• A.R. Hambley, Electronics, © Prentice Hall, 2/e, 2000

• A. Sedra and K.C. Smith, Microelectronic Circuits, © Oxford University Press, 4/e, 1999

• http://ezinearticles.com/?OLED-Lighting-and-LED-Lighting:--The-Difference-between-LED-and-OLED&id=460933

• A. Dodabalapur, “The future of organic semiconductor devies,” Device Research Conference 2000, Conference Digest, pp. 11-14, June 2000.

• H. E. Katz, Z. Bao, and S. J. Gilat, J. Acc. Chem. Res., vol.34, pp.359, 2001.

• N. Greenham and R. H. Friend, in Solid State Physics: Advances in Research and Applications, Vol. 49, H. Ehrenreich and F. Spaepen, Eds., Academic Press, San Diego, 1995, pp. 1–149.

• A. J. Lovinger and L. J. Rothberg, “Electrically Active Organic and Polymeric Materials for Thin-Film- Transistor-Applications,” J. Mater. Res. 11, 1581 (1996).

• N. Hirohata, T. Tada and S. Yagyu: Proc. Int. Display Workshop 2004(IDW’04), p. 355.

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Thank You