OLED is the next-generation display technology - using Organic Light Emitting Materials, one can create stunning displays that are very thin and efficient.
In October 2007,Sony introduced the world's first OLED TV - the XEL-1. This first model is a highly priced (~2,500$), small sized (11") Television - more of a commercial-prototype than anything else, Sony only made around a thousand units a month, and have recently stopped production.
Sony announced in May 2008 that they are working on a new TV. This one will be a 27" model - which is large enough to be called a television indeed. Sony even showed us a prototype of that screen.
But the XEL-2 never saw the light of day, and in fact Sony pulled out of the OLED TV business in 2013.
Later in 2017 Sony re-entered the OLED TV market, with a real 55"/65"/77" OLED TV, the XBR-A1E. Sony's OLED TV uses WRGB OLED panels produced by LG Display.