“OLED” or Organic Light Emitting Diode video display panels are the latest technology poised to replace the current generation of Plasma and LCD panels.

OLED displays are based on the organic process of “electro phosphorescence”. Think of Fireflies, plankton, and many sea creatures, they all have the ability to produce organic light.

OLED panels are based on electro phosphorescence research.  The panels use electrical current to stimulate organic materials (typically polymers) to produce red, green, blue, and white light. They do not require a backlight, use a third the power, have a wide viewing angle, have a contrast ratio of 1,000,000:1, can produce 16 million colors, and refresh at 200 times per second for extremely smooth motion. However, like most emerging technologies, OLEDs have a lot of advantages and a few disadvantages.

OLED Technology… OLED displays contain several thin layers stacked up to allow “electrical current” to flow through the layers. Based on the attraction of positively and negatively charged particles, current flows from the “Cathode Layer”, through the organic material, to the transparent “Anode Layer”.  As current flows between the cathode and anode the mid-layer organic material is stimulated to produce visible light.  The color of the light is dependent on the type of organic material placed between the cathode and anode. OLED panel layers are laminated on a substrate of clear plastic, glass, or foil. The layers vary depending on the intended function of the panel, but the basic structure contains the following layers.

- Substrate: Provides a base for the display (clear plastic, glass, or foil)

- Anode: Removes electrons when the current flows

- Conductive Organic Layer: Creates the electron “holes” when current is applied

- Emissive Organic Layer (creates light): Transports electrons from the cathode

- Cathode: Injects electrons when the current (electricity) flows

A Passive or Active matrix is used to control how and when the OLED display produces light. Passive-matrix OLED (PMOLED) panels use strips of anodes and strips of cathodes off-set by 90 degrees to create an X-Y grid. The intersections of the strips create the pixels where the light is emitted. Energizing selected strips determines which pixels turn on and which ones remain off. PMOLED displays are inexpensive to produce, but limited to small screens (2 to 3 inch diagonal). Passive displays are best suited for text and icons, and are found in cell phones, PDAs, and automotive dash boards.

Active-matrix OLED (AMOLED) panels use a “thin film transistor” (TFT) array to form a control matrix. The TFT array contains the circuitry to turn on the required pixels to form an image. AMOLED’s are used for large screen video displays.

OLED Pros and Cons… Some of the advantages of the OLED for HDTV displays; extremely fast refresh rate for smooth motion, no back-light required, ultra thin panels (3 – 10 millimeters), flexible substrate for roll-up displays, transparent displays as depicted in the film “Minority Report”, 170 degree viewing angle. The disadvantages are they’re expensive to manufacture, have only a 10,000 hour (3 year) life span for the blue organic layer, the OLED matrix is easily damaged by water and requires a method of moisture sealing to protect the display.

Future Applications… One of the more interesting applications of the OLED technology is in room lighting. White OLED panels emit light that is brighter and more energy efficient then fluorescent lights. White panels can be produced in a variety of color temperatures.Other OLED suggestions include foldable electronic newspapers, wall-size television monitors, and heads-up instrumentation for aircraft and automotive windshields.

For additional information take a look at the following links…

CES 2007 video report on OLED TVs http://www.youtube.com/watch?v=5rMFZ4O_oLs

Sony’s 11″ OLED panel ($2,500) http://www.sonystyle.com/webapp/wcs/stores/servlet/CategoryDisplay?catalogId=10551&storeId=10151&identifier=S_BrandShowcase_OLED&SR=sensory:shop:oled:ss&ref=http%3A//www.sony.com/index.php

OLED-TV Display/Monitor Technology News  http://www.oled-display.net/oled-television

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Chris Vazquez can be contacted at chris.designsmith@verizon.net or 301.953.1427

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