Tensile Strain and Water Vapor Transport Testing of Flexible, Conductive and Transparent Indium-Zinc-Oxide/Silver/ Indium-Zinc-Oxide Thin Films

Thin film laminates composed of sputtered indium zinc oxide and silver, optimized for conductance and transparency, were tested for water vapor permeation as well as mechanical durability in tension. The ∼ 82 nm thick optimized indium-zinc-oxide/silver/indium-zinc-oxide (IZO/Ag/IZO) films were > 80% transparent in the visible range (400 nm-700 nm) with measured sheet resistances less than 5 Ω/sq. The water vapor permeation measurements using Ca test methods at several temperature/ humidity conditions indicated that the addition of the thin Ag layer provided little improvement relative to a single indium-zinc-oxide (IZO) layer of similar thickness. However, the critical strain in bending tests for IZO/Ag/IZO films was improved compared to IZO films. The modulus (E ∼ 113 GPa), hardness (H ∼ 7 GPa), fracture toughness (K_IC ∼ 1.1 MPa·m^0.5), and interfacial shear ("adhesion") (τ_c ∼ 16 MPa) of/related to IZO, and measured by nanoindention are consistent with other brittle ceramic thin film materials.