Failure criterion of silver nanowire electrodes on a polymer substrate for highly flexible devices

Abstract

Nanomechanical characteristics of standalone silver nanowires (Ag NWs) are a key issue for providing a failure criterion of advanced flexible electrodes that are trending towards smaller radius of curvatures (ROCs). Through in-situ tensile and buckling tests of pentagonal Ag NWs, we demonstrated that the intrinsic fracture strain provides a significant criterion to predict the mechanical and electrical failure of Ag NW electrodes under various strain modes, because the decrease in fracture strain limits figure of merit of flexible devices. The Ag NW electrodes on a polymer substrate exhibited a strain-dependent electrical failure owing to the unique deformation characteristics with a size-dependent brittle-to-ductile transition of the five-fold twinned Ag NWs. All the Ag NWs greater than approximately 40 nm in diameter exhibited brittle fracture with a size-independent stress-strain response under tensile and buckling modes, which leads to the electrical failure of flexible electrodes at the almost same threshold ROC. Meanwhile, the higher ductility of Ag NWs less than 40 nm in diameter resulted in much smaller threshold ROCs of the electrodes due to the highly extended fracture strains, which can afford a high degree of freedom for highly flexible devices.

Operation Range-Optimized Silver Nanowire Through Junction Treatment

“…Conversely, in the laser-welded AgNW electrode, heat is selectively applied only to the junction site using a plasmonic effect; thus, adhesion site is localized to the junction contact area. Therefore, the rupture of individual nanowire occurs away from the junctions where adhesion is not enhanced at a low strain of 2-4%, which matches the previously reported rupture strain range of individual AgNW [29][30][31]. Although resistance marginally increases at a low tensile strain due to individual rupture, the laser-welded AgNW can bend and slide at higher strains due to partially enhanced adhesion onto the substrate.…”

Highly Bendable and Durable Transparent Electromagnetic Interference Shielding Film Prepared by Wet Sintering of Silver Nanowires

“…However, ITO is unsuitable for use as a transparent flexible material , because it is brittle and fractures easily. Moreover, its threshold radius of curvature (ROC) is greater than 7 mm, which is defined as the ROC at which a 10% change in the electrical resistance is observed. Al-doped ZnO, developed as an alternative to ITO, exhibits relatively high flexibility and high optical relative transmittance (84.1%); however, it suffers from a poor shielding performance of 6.5 dB at frequencies of 0.3–1.5 GHz, which limits its use as a transparent shielding material.…”

Transparent and conductive nanomembranes with orthogonal silver nanowire arrays for skin-attachable loudspeakers and microphones

“…On the other hand, this reduces the ductility of the composite film. In contrast to this behavior, our hybrid NM exhibits a progressive increase in the indentation displacement as the AgNW density increases, owing to the high ductility of nanosized AgNWs with the large aspect ratio and stretchability of the AgNW networks, which is advantageous for flexible device applications ( 44 , 45 ).…”