This prototype uses Sony's "Super Top Emission" technology and oxide semiconductor TFTs, the goal being to give all the benefits of OLED TV in a larger, 4K panel.
Sony's professional OLED monitors
Here are 30-inch (4,096x2,160-pixel resolution) and 56-inch (3,840x2,160) OLED prototypes. From the press release:
"The 'A' Series includes the BVM-E250A and BVM-E170A master monitors for high-end cinema and broadcast applications, the BVM-F250A and BVM-F170A master monitors for TV productions and broadcasting, and the versatile PVM-2541A and PVM-1741A picture monitors for a wide range of monitoring applications."