Ultrathin Au Electrodes Based on a Hybrid Nucleation Layer for Flexible Organic Light-Emitting Devices

We report an ultrathin Au transparent electrode with the thickness of only 4.4 nm based on an S-1805/Ag hybrid nucleation layer and its application in flexible organic light-emitting devices (OLEDs) as the replacement of indium tin oxide (ITO) anode. The Volmer-Weber growth mode of the deposited Au film has been suppressed successfully by using the hybrid nucleation layer, in which the S-1805 acts as a substrate modification layer and 0.6 nm Ag acts as a seeding layer. The resulting ultrathin Au film with the thickness of 4.4 nm shows high transparency, high conductivity, and ultrasmooth surface. A 25% improvement in efficiency has been demonstrated for the OLEDs with ultrathin Au anodes compared to the ITO-based devices. The application of the high-performance ultrathin Au electrodes in OLEDs results in high flexibility and mechanical robustness with small performance variations after 2100 bending cycles with a 7.5 mm bending radius.