Mechanical stability of externally deformed indium-tin-oxide films on polymer substrates

In this study, we investigated the basic mechanical properties of indium-tin-oxide (ITO) films on polymer substrates which are exposed to externally inducing bending force. By using the Storney formula including the triple layer structure and bulge tests for measuring the conductive changes of patterned ITO islands as a function of bending curvature, the mechanical stability of ITO films on polymer substrates was intensively investigated. Numerical analyses and experimental results show that externally induced mechanical stress in the films depends on substrate material and its thickness, respectively. Therefore,. an organic buffer layer was employed to improve the mechanical stability of ITO films, and then, the effects of the buffer layer. were quantified in terms of conductivity-strain variations. As a result, it is found that a buffer layer is also a critical factor for determining the magnitude of mechanical stress and that the layer with Young's modulus lower than the specified value can contribute to relieving the mechanical stress of the films.