Fascinating Facts About OLEDSFascinating facts about OLEDS. 10/22/2005 6:55 AM Eastern
Fascinating Facts About OLEDS
Fascinating facts about OLEDS.
- OLEDs are solid-state devices that are 100 to 500 nanometers thick — about 200 times thinner than a human hair.
- An OLED consists of a substrate, anode, two organic layers, and cathode.
- An OLED's organic layers are conducting layers made of organic plastic molecules that transport holes from the anode and an emissive layer, which is made of organic plastic molecules that transport electrons from the cathode.
- There are three ways to apply the organic layers to the substrate to manufacture an OLED: vacuum deposition or vacuum thermal evaporation, organic vapor phase deposition, and inkjet printing. In vacuum deposition, the organic molecules are gently heated (evaporated) and allowed to condense as thin films onto cooled substrates in a vacuum chamber. Organic vapor phase deposition takes place in a low-pressure, hot-walled reactor chamber where a carrier gas transports evaporated organic molecules onto cooled substrates that condense into thin films. OLEDs can also be sprayed onto substrates using inkjet technology, similar to the process in which inks are sprayed onto paper during printing.
- There are six types of OLEDs: passive-matrix, active-matrix, transparent, top-emitting, foldable, and white.
- Passive-matrix OLEDs (PMOLEDs) consist of strips of cathode, organic layers, and strips of anode. The anode strips are arranged perpendicular to the cathode strips, and intersections of the cathode and anode make up the pixels where the light is emitted.
- Active-matrix OLEDs (AMOLEDs) consist of full layers of cathode, organic molecules, and anode, but the anode layer overlays a thin transistor film (TFT) that forms a matrix. The TFT is the circuitry that determines which pixels get turned on to form an image.
- Transparent OLEDs have only transparent components (substrate, cathode, and anode) that when turned off are up to 85 percent as transparent as the substrate. A transparent OLED can either be active- or passive-matrix.
- Top-emitting OLEDs have an opaque or reflective substrate that's best suited for active-matrix design.
- Foldable OLEDs have substrates made of very flexible metallic foils or plastics. Foldable OLEDs are used in devices such as cell phones and PDAs, and can potentially be sewn into fabrics to make “smart” clothing.
- White OLEDs emit white light that is brighter, more uniform, and more energy efficient than fluorescent lights. They can be used in homes and buildings.