Introduction to OLEDs, OLED TVs

What is it all about?

OLED (Organic Light Emitting Diodes) is a flat display technology, made by placing a series of organic thin films between two conductors. When electrical current is applied, a bright light is emitted.

Because OLEDs produce (emit) light they do not require a backlight. This means that OLEDs can be made very thin and very power efficient when compared to LCD (which do require a white backlight). OLEDs can be used to create white-light, too.

So what does it mean to me?

OLEDs have the following advantages over today's flat-panel tech (LCD or plasma):

• Low power consumption - OLEDs are a far better choice for portable devices. It also makes OLEDs much more environmental friendly, and a candidate to be the white-light "bulb" of the future
• Faster refresh rate and better contrast.
• Greater brightness - The screens are brighter, and have a fuller viewing angle.
• Exciting displays - new types of displays, that we do not have today, like ultra-thin, flexible or transparent displays.
• Better durability - OLEDs are very durable and can operate in a broader temperature range
• Lighter weight - the screen can be made very thin, and can even be 'printed' on flexible surfaces

How does it work?

An OLED is made by placing a series of organic thin films between two conductors. When electrical current is applied, a bright light is emitted. Here's Kodak's description of OLEDs -
"OLED displays stack up several thin layers of materials. They operate on the attraction between positively and negatively charged particles. When voltage is applied, one layer becomes negatively charged relative to another transparent layer. As energy passes from the negatively charged (cathode) layer to the other (anode) layer, it stimulates organic material between the two, which emits light visible through an outermost layer of glass."

So what's organic about OLEDs?

OLEDs are organic because they are made from carbon and hydrogen (see Organic Chemistry in Wikipedia). There's no connection to organic food or farming...

What's the difference between AMOLED and PMOLEDs?

These terms relate to the driving method of the OLED display. With Passive-Matrix (PMOLED), one controls the display by switching a certain row and column - in effect lighting the pixel at the intersection. The pixels are turned on and off quickly, and the sequence creates the image. With Active-Matrix (AMOLEDs)one controls each pixel directly. Passive-Matrix OLEDs
are easy and cheap to make, but has a high power consumption and
only allow for small sized displays (up to 3", typically). Making
larger and more efficient displays require the use of AMOLEDs – but these are more expansive to make.

So if you're looking for a TV, it'll probably be an AMOLED TV. PMOLEDs are used in mp3 players, secondary displays on cell phones, etc.

What kind of materials are used to make OLEDs?

OLED materials can be divided into small- and large- molecules. 'Small Molecules' OLEDs are more common today, with most displays using those kind of materials. Large Molecules (also called Polymer-based OLEDs, or P-OLEDs) are lagging behind in lifetime and efficiency specs. P-OLEDs might be easier to make, though, because they are more easily adapted for printing. Indeed, one can 'ink-jet-print' an OLED, which is a great way to make them. 

OLEDs can also be classified based on another property of the material –
whether it is fluorescent or phosphorescent. Most displays today are built using fluorescent materials, while Phosphorescent OLEDs (PHOLEDs) promise to deliver even more efficient displays. Sometimes the display use a mix of fluorescent and phosphorescent materials – for example Samsung SDI's displays use Red PHOLEDs and fluorescent red and green.

Where can I find OLED displays today?

Today you can find small (up to 3 or 4 inch) organic displays in many types of devices - Cell phones, A/V players, car audio systems, Digital cameras and PDAs. The main attraction today is the small size, the low power consumption and the great brightness.
Here's our list of products and gadgets with an OLED display.

Why can't I buy an OLED TV?

Actually you can, sort of. In November 2007 Sony began to sell a limited amount of the world's first OLED TV - the 11" XEL-1 (for about 2000$). It's actually more of a prototype than a real commercial product. Building large sized OLED displays is not easy, and it will take some time before companies are able to do it economically. One of the main challenges in oled displays are the life time, especially of the blue color, which is problematic for larger screens. There are constant progress in the lifetime of OLEDs, though.

Several companies (notably Sony, Samsung, LGDisplay, Toshiba and Panasonic) are working towards larger OLED displays, and hopefully by 2009 we'll see them available - probably around 10"-14" OLEDs for laptop displays at first.
Read more about OLED TVs here, including the latest news

Can OLED produce white lighting?

One of the more exciting attributes of organic displays is the low power consumption, and the ability to operate as a light source. OLEDs can produce white light, and can provide the bulb of the future - low power and thin designs. As energy prices go up, and environmental issues take center stage, we can expect fast development in this field. Several companies are working towards OLED lighting, and hopefully we'll see some commercial products around 2011.
Read more about OLED white light here, including the latest news