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OLEDs are available as distributed sources while the inorganic LEDs are point sources of light. Prior to standardization, OLED technology was also referred to as OEL or Organic Electro-Luminescence.
One of the great benefits of an OLED display over the traditional LCD displays found in computer displays is that OLED displays don't require a backlight to function. This means that they draw far less power and they can be used with small portable devices which have mostly been using monochrome low-resolution displays to conserve power. This will also mean that they will be able to last for long periods of time with the same amount of battery charge.
The world's first digital camera with an OLED display was the Kodak LS633 model revealed at the Photo Marketing Association (PMA) trade show in March 2003.
See also: Flexible electronics
There are two main directions in OLED.
The first technology was developed by Eastman-Kodak and is usually referred to as "small-molecule" OLED. The production of Small-molecule displays requires vacuum deposition which makes the production process expensive and not so flexible.
A second technology, developed by Cambridge Display Technologies or CDT, is called LEP or Light-Emitting Polymer.The light-emitting polymer material consists of chains of molecules. Although this technology lags the Small-Molecule development by several years, it is more promising because of an easier production technique. No vacuum is required, and the OEL materials can be applied on the substrate by a technique derived from commercial ink-jet printing. This means that LEP displays can be made in a very flexible and cheap way.
OLEDs work on the principle of Electroluminescence. The key to the operation of an OLED is an organic dye. This dye has exciton states, which consist of an excited electron and a hole (empty state) it can fall into. When the electron and hole combine, a photonFor the Japanese anime video, see Photon (anime). In physics, the photon (from Greek φοτος, meaning light is a quantum of excitation of the quantised electromagnetic field and is one of the elementary particles studied by qu is emitted. The tricky part is the creation of the proper excitons. It can be done by shining light on the dye, which creates fluorescenceultraviolet light in vials containing various sized cadmium selenide (CdSe) quantum dots. Fluorescence is a luminescence, i. optical phenomenon in cold bodies, in which a molecule absorbs a high-energy photon, and re-emits it as a lower-energy (longer-wav. But the goal is to have a device that emits its own light.
To create the excitons, a thin film of the dye is used, and a current is passed through it in a special way. Excited electrons are injected into one side from a metal cathodeThe electrode of an electrochemical cell at which reduction occurs is referred to as the cathode . In an electrolytic cell the cathode is negatively charged and in a galvanic cell the cathode is positively charged. The oppositely charged electrode in that, while holes are injected in the other from an anodeAn anode is the positive electrode in an eletrolytic system or circuit. Literally, the path through which the electrons ascend out of an electrolyte solution. In electrochemistry, the anode is where oxidation occurs and is also the negative discharge plat (think of the anode as sucking electrons out of the dye). These electrons and holes move into the dye and meet to form excitons. Then when the excitons decay (the electron falls into the hole), they often give off the light we are looking for.
Derivatives of PPV, poly(p-phenylene vinylene)Poly(p-phenylene vinylene (PPV) is conducting polymer of the rigid-rod polymer host family. External links ., are commonly used as the polymerA polymer is a long, repeating chain of atoms, formed through the linkage of many molecules called monomers. The monomers can be identical, or in complex polymers such as proteins the monomers have one or more substituted chemical groups, this gives them dyes in OLEDs. Indium tin oxideIndium tin oxide ITO is a mixture of indium(III) oxide (InO) and tin(IV) oxide (SnO), typically 90% InO, 10% SnO by weight. ITO is mainly used to make transparent conductive coatings for electronic displays, and heat-reflecting coatings for architectural, is a common anode, while aluminum is a common cathode. Other materials are added in between the cathode/anode and the dye layer to enhance the efficiency. You may find more materials for this technology.