As promised, Panasonic showed 56" 4K (3840x2160) OLED TV panel at the IFA 2013 exhibition. The company had several prototypes on display, and I believe these are the same panels as the ones Panasonic unveiled at CES 2013 in January 2013.
Panasonic panels are made using an "all-printing" method, and Sumitomo Chemical revealed that these prototypes use the company's PLED materials. Panasonic's panel uses a substrate (probably Oxide-TFT) provided by Sony (which are actually made by AU Optronics) - as part of the two companies collaboration. According to the latest reports, they only plan to start OLED production at around 2015.