Highly flexible, transparent, and low resistance indium zinc oxide-Ag-indium zinc oxide multilayer anode on polyethylene terephthalate substrate for flexible organic light 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 Ω/□ 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 IAI 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.