Here Comes the Oled

By: Ron Mertens

OLED (Organic.Light.Emitting.Diode) is a new display technology that promises to deliver thin, power efficient and bright displays. OLEDs (already popular in MP3 players and cell phones) have amazing potential - thin TVs, flexible displays, transparent monitors, white-bulb replacement, and more.

LCD works by having a backlight (white light) source, and then filtering this source to make colors. OLEDs however work by emitting color light. This has several advantages. It allows to make simpler and thus thinner and cheaper displays. It also means that OLEDs require less power. Think that when you have a screen that is completely black (but turned on), LCD will still require the whole white backlight to be emitted. With OLEDs, no energy is consumed in this stage! It is also possible to make flexible OLED displays, and even transparent ones, but this is obviously more challenging than a simple LCD-like display.

While OLEDs are heralded as the display technology of the future, they are already produced and used today. While making large panels is still a great challenge, smaller screens (up to 2") are already produced in commercial quantities today. There are many MP3 players and cellular phones that use OLED displays. Companies such as Sony and Samsung use OLED displays in their leading models. The OLED market reached 500$ million in sales in 2005, and is expected to grow quickly in the coming years.

There are two main types of OLED screens Passive Matrix (PMOLED) and Active Matrix (AMOLED). PMOLED displays are cheaper and easier to manufacture, but they have a limitation in resolution, size and refresh rate. Most OLEDs that are being made today are PMOLED. However several companies (including Samsung SDI and LG.Philips) have announced plans to begin producing AMOLED panels in 2007.

The future for large OLED panels is not so certain. The major limitation of OLED technology today is the lifetime, especially for the blue color. Progress is being made all the time, but the technology is not ready yet. Scaling the OLED screens is not an easy thing to do, either. Making a large panel (for TV or computer screen) is far from simple. While prototypes have been showed, it will take several years before we'll be able to buy an OLED television.

OLEDs actually make it possible to create screens that are flexible and/or transparent. The possibilities of this kind of displays are almost endless. Think about car windshield-embedded transparent displays, or rollable mobile TV. This technology is still at an early stage, but already companies are showing prototype and design sketches.

One of the areas that seem most promising for OLEDs is white lighting. Many companies are hoping that OLEDs will enable very efficient light sources. With today's high energy costs, and the drive for efficiency, there is a lot of money in white-light research, and OLEDs are seen as one of the best future technologies. OLEDs will also enable unimaginable designs, because of their thin and flexible nature.

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