Elucidating the effect of Ag interlayer formation on the intrinsic mechanical properties of free-standing ITO/Ag/ITO thin films

Abstract

The lack of characterization of the mechanical behavior of brittle indium tin oxide (ITO)-based electrodes has been a core issue for the development of advanced transparent and flexible electronics. In this study, we report the intrinsic mechanical properties of ITO/Ag/ITO (IAI) thin films measured by a free-standing tensile testing method for robust transparent electrodes. To understand the effect of Ag interlayer formation on the mechanical properties, Ag thickness is controlled (8–50 nm) by considering the stage of the film formation. Based on the tensile test, IAI thin films with a film-likely formed Ag interlayer (12–14 nm) exhibited outstanding mechanical robustness compared with island-(8 nm) or film-type (>25 nm) Ag interlayers. Notably, the most superior elongation and tensile strength (0.57 ± 0.08% and 514.3 ± 71.5 MPa) are demonstrated for 14 nm-thick Ag interlayer, which is two-fold higher than pristine ITO thin films (0.27% and 264.6 MPa). The study provides intrinsic mechanical property values and fundamental insights into the fracture mechanisms that govern the mechanical behavior of oxide/metal/oxide multilayer thin films, which is valuable for the development of flexible electronics.