Highly Robust and Strain-Resilient Thin Film Conductors Featuring Brittle Materials.

Chen, Kai; Zhang, Linyuan; Wu, Kai; Yang, Chao; Wang, Ruihong; Xu, Canhua; Zhang, Jinyu; Liu, Gang et al. · Nano Lett · 2023

basic_science · Level V

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Abstract

Stretchable conductors with stable electrical conductivity under various deformations are essential for wearable electronics, soft robots, and biointegrated devices. However, brittle film-based conductors on elastomeric substrates often suffer from unexpected electrical disconnection due to the obvious mechanical incompatibility between stiff films and soft substrates. We proposed a novel out-of-plane crack control strategy to achieve the strain-insensitive electrical performance of thin-film-based conductors, featuring conductive brittle materials, including nanocrystalline metals (Cu, Ag, Mo) and transparent oxides (ITO). Our metal film-based conductors exhibit an ultrahigh initial conductivity (1.3 × 10<sup>5</sup> S cm<sup>-1</sup>) and negligible resistance change (<i>R</i>/<i>R</i><sub>0</sub> = 1.5) over wide strain range from 0 to 130%, enabled by film-induced substrate cracking and liquid metal-induced electrical self-repairing. They could function well under multimodal deformations (stretching, bending, and twisting) and severe mechanical damage (cutting and puncturing). We demonstrated the strain-resilient electrical functionality of metal film-based conductors in a flexible light-emitting diode display that shows high mechanical compliance.