The cohesive crack and buckle delamination resistances of indium tin oxide (ITO) films on polymeric substrates with ductile metal interlayers

This work presents the effect of inserting ductile metal interlayers on crack and buckling delamination resistances of indium tin oxide (ITO) on polymeric substrates. Ag is selected as an interlayer and is deposited on polyethylene terephthalate (PET) substrates in varying thicknesses. We dc sputter-deposit 150 nm-thick ITO onto PET substrates and evaluate mechanical resistances by measuring the strains at crack initiation and delamination under tension and compression, respectively. Compared to the samples without interlayers, both the crack and delamination resistances of ITO are significantly improved by Ag interlayers over a certain thickness. The increase in crystallinity of ITO by the interlayers results in cohesive strength improvement of ITO, which is the primary factor enhancing crack resistance. Enhanced adhesion strength by the interlayers seems to improve the delamination resistance. The internal stress relief afforded by the addition of interlayers is found to have negligible effects on crack resistance compared to crystallinity.