Highly enhanced mechanical stability of indium tin oxide film with a thin Al buffer layer deposited on plastic substrate

We here report that the mechanical stability of indium tin oxide (ITO) film deposited on the plastic substrate can be highly enhanced by a thin metal buffer layer with a minimized loss of transparency. Neither cracks nor fragmentation was observed for a 75 nm-thick ITO film with a 5 nm-Al layer even after severe bending to a radius of curvature of 1.25 mm, while a 160 nm-ITO film of similar surface resistance was cracked at 9 mm. The improved crack resistance is accounted for by the fact that the effective elastic mismatch between the film and the substrate can be alleviated with a ductile buffer layer, thus the crack propagation is suppressed.