On March 2014, Sony unveiled the Morpheus VR HMD system, specifically designed for the PS4 console. The original prototype system shown by Sony used a 5" Full-HD (1920x1080) LCD panel, but reports said that Sony plans to replace the LCD with an OLED display in the production model.
Now Sony unveiled a newer prototype of the Morpheus VR headset, which indeed uses an OLED display - a 5.7" 1920x1080 one. This OLED has lower latency (under 18 ms) and a higher field of view. Sony also said that the headset will launch in the first half of 2016. This is not a huge surprise - OLED enables a much faster display which is crucial for VR applications. Oculus's VR system also uses an OLED panel.