Researchers from Korea's ETRI (Electronics and Telecommunications Research Institute) developed a flexible OLED panel that use a transparent graphene electrode. ETRI will detail this new graphene-based OLED panel at SID DisplayWeek 2018 in May.
A rigid graphene-based OLED prototype (ETRI 2017)
The researchers produced a "fully operational" 40x40 mm OLED panel that uses the pixelated graphene film as electrodes.
Last year ETRI researchers demonstrated a 370x470 mm rigid OLED panel that use graphene electrodes (the panel was actually made from 12 individual OLED panels). You can see this panel in the photo above.