ORGANIC LIGHT EMITTING DIODE (OLED)

   The OLED has an emissive electroluminescent layer. This electroluminescent layer consists of a film of organic compounds. This organic compound film emits light if we provide an electric current to it. The layer of organic semiconductor is placed between two electrodes and typically one of these electrodes is made transparent.

   The OLEDs find a wide range of applications. They are being used in computer monitorsand television set screens. The portable system screens like mobile phones and PDAs also make use of this technology. The organic LEDs are also used in advertising, information and indication fields. The property of l space illumination I light sources also utilizes the OLEDs.

The light emitting elements are of various ranges. And the large area hitting light emitting elements uses an organic led. As these organic LEDs are in their early stages of development they emit comparatively less light per unit area than the inorganic LED point light sources which are solid state based.

   There is no backlight for an OLED. The displaying of functions is done in the absence of backlight. This makes OLED capable of displaying black levels. Also it becomes thinner and lighter than the liquid crystal displaying. On comparing to LCD, the OLEDs show a betterperformance in dark rooms. They are able to acquire a higher contrast ratio in such conditions if the LCD uses a cold cathode fluorescent lamp or a LED backlight that is developed very recently.

Substrate (clear plastic, glass, foil) - The substrate supports the OLED.

Anode (transparent) - The anode removes electrons (adds electron "holes") when a current flows through the device.

Organic layers - These layers are made of organic molecules or polymers.

Conducting layer - This layer is made of organic plastic molecules that transport "holes" from the anode. One conducting polymer used in OLEDs is polyaniline.

Emissive layer - This layer is made of organic plastic molecules (different ones from the conducting layer) that transport electrons from the cathode; this is where light is made. One polymer used in the emissive layer is polyfluorene.

Cathode (may or may not be transparent depending on the type of OLED) - The cathode injects electrons when a current flows through the device.