▎ 摘　　要

Outcoupling efficiencies (OCEs) of green phosphorescent organic light emitting diodes (OLEDs) with graphene anodes are theoretically analyzed using the classical electromagnetic model and are compared with the OLEDs with ITO anodes. The OCEs of the OLEDs with anodes of 3 or 4 graphene monolayers are comparable to an ITO based device with a 150 nm thick ITO, where both electrodes have a similar sheet resistance of about 24 Omega/square. However, the OCEs of graphene based OLEDs are lower than that for ITO based devices with a same sheet resistance in most cases. This limitation can be overcome by using a graphene/transparent conducting oxide (ITO or IZO) composite electrode, which can achieve high outcoupling efficiency, low sheet resistance and high transmittance at the same time. In addition to that, the light extraction techniques are expected to be much more effective in graphene based OLEDs than ITO based OLEDs, which is important for lighting application of OLEDs. (C) 2012 Elsevier B.V. All rights reserved.