Mechanical Properties of Tensile Cracking in Indium Tin Oxide Films on Polycarbonate Substrates

Abstract

The electro-mechanical behaviors of transparent conductive oxide film on polymer substrate are of great concern because they would greatly affect the stability and lifespan of the corresponding devices. In this paper, indium tin oxide (ITO) films with different thicknesses were deposited on a polycarbonate (PC) sheet; meanwhile, in situ electrical resistance, in situ scanning electron microscopy and profilometry were employed to record the electrical resistance, morphologies and residual stress in order to investigate the fracture behavior and electrical-mechanical properties of ITO films under uniaxial tension loading. The electrical resistance changes, crack initiation, crack propagation and crack density evolution of ITO films were systematically characterized by in situ tests. Three fracture stages of ITO films were summarized: Ⅰ crack initiation, Ⅱ crack propagation, Ⅲ crack saturation and delamination. The crack initiation and electrical failure in a thinner ITO film occurred at relatively higher applied tensile strain; namely, the ductility of the film decreased as the film thickness increased. Residual compressive stress was recorded in the ITO films deposited on PC at room temperature and increased as the film thickness increased. Intrinsic crack initiation strain (CIS*) showed an opposite thickness dependence to residual strain (εr); the increase in residual compressive strain was counteracted by the decrease of intrinsic cohesion, leading to an overall decrease in effective crack initiation strain (CIS) when the film thickness increased. In addition, integrated with a formulated mechanics model and the analysis of the three fracture stages under tension, the fracture toughness and interfacial shear strength were quantitatively determined. As the film thickness increased (in the range of 50~500 nm), the fracture toughness decreased and the films were more prone to crack, whereas the interfacial shear strength increased and the films were less likely to delaminate.

Effects of dielectric layer on ductility for dielectric/Au/dielectric multilayers on polycarbonate substrate

“…While CD increased significantly with tensile strain increased and saturated gradually marked as CD s . A rapid increase of the film resistance occurred at the initial stage of crack propagation, which is reflected in the increase of CD or the propagation of cracks across the whole width and depth of the sample [23]. The SEM image showing the different multilayers on PC substrates at the same tensile strain is presented in figure 2(d).…”

Thermal shock resistance and enhanced adhesion of ITO film on organic substrate through introducing a transparent SiO2-PMMA buffer layer

“…Transparent conductive films (TCFs), as essential components, are extensively used as transparent electrodes for flexible optoelectronic devices [1][2][3] (e.g., organic light-emitting diodes (OLEDs)、liquid crystal displays (LCDs)、organic photovoltaics (OPVs)) and electromagnetic shielding layers for stealth aircraft [4][5][6] (e.g., aircraft cockpit transparent parts). Among them, indium tin oxide (ITO) film exhibits the high transmittance in the visible、low resistivity、strong microwave attenuation properties、 good mechanical properties and chemical stability, making it the most commonly used TCF material.…”

Robust ZTO-reinforced Ag nanowire hybrid transparent conductive thin films with absorption-enhanced electromagnetic interference shielding property

“…For such flexible electronics applications, mechanical stability and durability are the prerequisites for transparent conducting thin films (TCFs) along with efficient transparency and conductivity [6,7]. When mechanical properties are a particular concern, conventional metal oxide TCFs such as tin-doped indium oxide, which is an important TCF in the transparent electronics industry, fails to meet the explicit criteria due to its brittleness and a processing temperature that is incompatible with flexible substrates [8][9][10][11]. To address these issues it is vital to explore alternative materials or strategies to fabricate efficient flexible transparent electrodes.…”