The organic films consist of a hole-injection layer, a hole transport layer, an emissive layer and an electron-transport layer. When voltage is applied to the OLED cell, the injected positive and negative charges recombine in the emissive layer and create electroluminescent light. Unlike LCDs, which require backlighting, OLED displays are emissive devices - they emit light rather than modulate transmitted or reflected light.
OLED technology was invented by Eastman Kodak in the early 1980s. It is beginning to replace LCD technology in handheld devices such as PDAs and cellular phones because the technology is brighter, thinner, faster and lighter than LCDs, use less power, offer higher contrast and are cheaper to manufacture. An important step in the evolutionary process began with the use of thin-film organic layers. The first EL thin-film device used a single organic layer sandwiched between two injecting electrodes.
OLEDs are the latest and most promising buzzwords in display technology. To give you an idea of their potential, imagine a cardboard-thin TV screen. Now imagine that you can roll up your TV, put it away or carry it wherever you go. Automatically, you start appreciating why millions, if not billions, of dollars, are being poured into OLED research every year.
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