OLED stands for Organic Light Emitting Diodes.
The main differences between OLED and LED include illumination method, picture quality, price and energy efficiency. The primary difference between OLED and LED is the method used to create the picture. OLEDs use organic compounds to create the picture when electricity enters the diode.
OLEDs offer superior technology, which generates a wider range of colors than LEDs. OLED technology illuminates each pixel independently and generates the deepest black of any diode in a flat-screen display. OLEDs are also curved and feature a larger viewing angle. The colors on LED displays become washed out and flat when viewing from different angles. This superior technology also allows OLED displays to provide a lighter and thinner product. The individual LEDs inside LED displays are heavier and space consuming, while individual OLEDs do not require backlight and use less power. As a result, OLED displays are more energy efficient. OLEDs also have better response times and are more flexible than LEDs.
 OLED Displays
OLED displays compete for many of the same segments of the display market. Analysts predict they will have long-term opportunities in applications ranging from packaging to mobile electronics to televisions.
Providers of OLED displays have market opportunities in increasing the life of OLEDs, small- to medium-size television displays, specialized drivers/electronics for OLED displays, printed backplanes and low-cost displays for disposable items.
 OLED Technology Providers
|AU Optronics Corporation||Taiwan|
|Cambridge Display Technology||Cambridge, UK|
|Eastman Kodak||Rochester, NY|
|MicroEmissive Displays||Edinburgh, UK|
|Next Sierra||Mountain View, CA|
|Palto Alto Research||Palto Alto, CA|
|Plastic Logic||Cambridge, UK|
|Toppan Printing||Tokyo, Japan|
|Universal Display Corp.||Ewing, NJ|
Kodak's OLED employs a basic structure of organic layers squeezed between a transparent anode and a metal cathode. The organic layers include a hole injection layer, an emitter layer, and an electron transport layer. When a voltage is applied to the cathode and anode, the organic emitters produce light (called electroluminescence) that’s released through a substrate layer. In current OLED products, the substrate layer is usually made of glass. By adding small amounts of highly fluorescent molecules to the organic emitters, the efficiency and color of the output has been greatly enhanced.
There are some variations in the technology.
 Transparent OLED
TOLED (Transparent OLED) can appear as a top-only emitting, bottom-only emitting, or both top-and-bottom-emitting product. With TOLED technology, the contrast in the display increases tremendously, making it easy to view in bright sunlight. A TOLED product is 70% transparent when turned off, meaning it could be a good technology for use in products such as car windshields or eyeglasses. To make TOLED work, voltage is applied to the anodes on both sides of the stack. The organic emitters in the middle then produce Electroluminescent light in both directions. The stack of layers looks like:
- Electroluminescent Light output
- Anode - negative side voltage
- Metal Cathode
- Emitter Layers
- Anode - positive side voltage
- Electroluminescent Light output
 Stacked OLED
SOLED (Stacked OLED) uses stacked TOLED subpixels, which provide outstanding true color. In an LCD or CRT, the pixels representing green, red, and blue are side by side. But in SOLED, each of the three pixels are stacked, providing truer colors. Each subpixel can be individually controlled, allowing the colors to mix at exactly the correct ratio to create the desired color.
SOLED displays can offer about three times the resolution of a similar LCD because of its three-colors-in-one pixels. SOLED also maximizes the fill factor. In a traditional LCD, only the green pixels would be active in an all-green area; the red and blue pixels would be inactive, leaving blank spaces. At low resolutions, the blank spaces aren’t noticeable, but in applications where high resolutions and sharp images are needed, the maximum fill factor available with SOLED is desirable.
 For more information
- https://en.wikipedia.org/wiki/OLED which also mentions AMOLED