Highly flexible, transparent, and low resistance indium zinc oxide-Ag-indium zinc oxide multilayer anode on polyethylene terephthalate substrate for flexible organic light-emitting diodes

Abstract

The characteristics of indium zinc oxide (IZO)-Ag-IZO multilayer grown on a polyethylene terephthalate (PET) substrate were investigated for flexible organic light-emitting diodes (OLEDs). The IZO-Ag-IZO (IAI) multilayer anode exhibited a remarkably reduced sheet resistance of 6.93 Omega/square and a high transmittance of 84.8%, despite the very thin thickness of the IZO (30 nm) layer. In addition, it was shown that electrical and optical properties of [A] anodes are critically dependent on the thickness of the Ag layer, due to the transition of Ag atoms from distinct islands to continuous films at a critical thickness (12 nm). Moreover, the IAI/PET sample showed more stable mechanical properties than an amorphous ITO/PET sample during the bending test due to the existence of a ductile Ag layer. The current density-voltage-luminance characteristics of flexible OLEDs fabricated on an IAI/PET substrate was better than those of flexible OLEDs fabricated on an ITO/PET substrate. This indicates that IAI multilayer anodes are promising flexible and transparent electrodes for flexible OLEDs. (C) 2008 Elsevier B.V. All rights reserved.