Indium Tin Oxide (ITO) is one of the most widely used transparent conducting oxides in applications such as electronic displays and solar cells. The low resistivity and high transmittance of ITO have led to the recent explorations of polymer-supported ITO films as the transparent electrodes in flexible electronics. Flexible devices are often subject to repeated large deformation. While compliant polymer substrates can sustain large strain, brittle ITO films often fracture at a small strain. The cracking of ITO electrodes leads to loss of electrical conductance, posing crucial challenge to the reliability of flexible devices. As an effort to address this challenge, here we report a multilayer structural design of ITO-based electrodes with enhanced electro-mechanical durability. In particular, our in situ electro-mechanical experiments and coherent mechanics modeling reveal that, a top protective polymeric coating above and an intermediate polymeric layer below the ITO electrode can effectively reduce the driving force for cracking of the ITO electrode. The findings of the present paper suggest a feasible solution to durable transparent electrodes for flexible electronics.The multilayer structural design of ITO-based electrodes in the present study is inspired by the recent progress in designing high performance permeation barriers for flexible electronics. While flexible electronics is being developed toward an array of promising applications (e.g., paper like displays and sensitive electronic skins, etc.), [1][2][3][4][5][6] the service life of flexible devices is limited due to the vulnerability of functional organic layers in flexible devices to the attack of environmental water vapor and oxygen. High performance COMMUNICATION Indium Tin Oxide (ITO) films are widely used as transparent electrodes in electronic displays and solar cells. However, the small fracture strain of brittle ITO films poses significant challenge to their applications in flexible electronics devices that often undergo large deformation. Inspired by recent development of inorganic/organic hybrid permeation barriers for flexible electronics, we design and fabricate ITO-based multilayer electrodes with enhanced electro-mechanical durability. In situ electro-mechanical experiments of five structural designs of ITO-based multilayer electrodes are performed to investigate the evolution of crack density and the corresponding variance of electrical resistance of such electrodes. A coherent mechanics model is established to determine the driving force for crack propagation in the ITO layer in these electrodes. The mechanics model suggests that a top protective polymeric coating above and an intermediate polymeric layer below the ITO layer can effectively enhance the mechanical durability of the ITO electrodes by reducing the crack driving force up to 10-folds. The modeling results offer mechanistic understanding of the in situ experimental measurements of the critical fracture strains of the five types of ITO-based multilayer electrodes. The findin...

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Ni-based bulk metallic glasses and composites with high absolute densities exceeding 11 g/cm3 were synthesized via spark plasma sintering of Ni45Co10Ta25Nb20 powders produced from pulverized, melt-spun amorphous ribbons. Optimizing the synthesis via selection of sintering temperature, uniaxial load pressure, and powder mechanical screening yielded samples with relative densities of nearly 100% and hardness values in excess of 12.5 GPa without cracking. Mechanical testing included Weibull modulus determination for hardness and compression testing at 10-3 s-1 and 103 s-1 strain rates. The capability of using spark plasma sintering to fabricate high hardness, high density, large scale metallic glasses is demonstrated. The mechanical properties of these compacted comminuted melt-spun glass ribbons are presented.

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