What are the advantages of OLED TV?

The result is remarkably dark blacks in an image, and when you combine this with the brightness of the whites an OLED panel is able to produce you're left with a fantastically vibrant image.
LG and Panasonic, pretty much the most consistent producers of OLED televisions on the planet, like to use the term "infinite contrast" to describe how the self-lighting pixels switch off completely when reproducing black giving it an "absolute" black color instead of a "relative" black that only describes how dark one pixel can get compared to the brightest pixel on the screen.

For years there was a question mark about longevity of OLED panels, while production lines have been impossible to make profitable due to high failure rates. But as companies like LG have invested huge quantities of money in the technology – with the likes of Philips and Sony joining the fray – its affordability has gotten better, although it's still much more expensive than competing technologies.
The advantages of OLED go beyond simple static image quality to the responsiveness and smoothness of the display itself, meaning gamers and home cinema aficionados are going to absolutely love OLED. It's capable of a refresh rate of as low as 0.001ms, which for reference, is around 1,000 times faster than a standard LED-backlit LCD panel, while also being superior to the now-discontinued plasma tech, too.
And, because the lighting source they use is so tiny, the depth of screen sizes has shrunk at the same rate. That means OLED TVs have awesomely deep blacks and bright, peak whites, improved color accuracy as well as smooth responsive motion - and all from a form factor that's just a few millimetres in depth and much lighter than standard TVs.

source:
www.techradar.com/news/television/oled-tv-what-you-need-to-know-1056228