Update: It turns out that the researchers did not fabricate an OLED lighting panel, but a small monochrome (green) OLED device.
Researchers from Philips, Graphenea and the University of Cambridge developed a new graphene-based transparent electrode that outperforms ITO in OLED devices.
Graphene by itself is not a good electrode material because the concentration of the charge carriers is low - which means that you need to dope it with excess carriers - while leaving it flexible and transparent. To achieve that, the team used a metal oxide film (molybdenum trioxide, MoO3) as an intermediate layer between the graphene and the OLED layers. The work was performed as part of the EU project GRAFOL, aimed at roll-to-roll mass production of graphene.