It turns out that Mitsubishi's Diamond Vision OLED displays (which go on sale today!) actually use PMOLED displays, and not AMOLEDs as we assumed. This is possible because each 'tile is only 128x128 in resolution. Using PMOLEDs allows Mitsubishi to make the displays cheaply (compared to AMOLEDs).
The OLED material used in the displays is small molecule, deposited by vacuum evaporation. The material was developed by Mitsubishi and Pioneer together. (the two companies are also collaborating on OLED lighting).