OLED screens are used on some smartphones (AMOLED) and other devices but they are only just now coming out for tvs. The OLED screen is so good that it's worth getting excited about the new televisions. If you are like me you you likely have some LEDs and/or plasma televisions in your home. I have previously written a Pages article about some of the differences among the currently available technology. OLED panels are quite different and they are quite good.
OLED stands for Organic Light-Emitting Diode. An OLED diode directly emits color by running a current through various "organic" materials that emit the colors required to create an image. LEDs use filters to emit color. Plasma charges tiny clouds of gas to emit color.
OLED tvs can be very thin- as thin as 1/4" (actually, one new model with be even smaller at 3/16"). They are also light in weight. For example, a 55" tv will weigh under 20lbs (some will be very close to 15lbs). A very thin and very light 55" almost starts to seem portable as it can easily be carried about by almost anyone.
Notice How Thin This TV Is!
OLEDs can be completely turned off to produce a true black. LED/LCD and plasma tvs cannot do that (old fashioned CRT displays can, however). The ability to turn a pixel completely off means a contrast range that is not available in current tv technology. The pictures will be bright, vibrant, and have some "punch" to them.
The first OLED tvs will be quite expensive. That was the case with LED/LCD and plasmas when they first came out. I bought my 42" plasma 1080p tv about six years ago for $1,200. Can you imagine paying that now for a 42" tv? The newer models are cheaper and better than mine. But, over time the OLED tvs will come down in price just as the other technologies already have. Indeed, I often see 32" 720p tvs on DP lately for very close to $200.
As usual, you can use a search engine to search on OLED TV and read about the technology in much greater depth. I hope this brief introduction was useful to you.