Electrically Interconnected Platinum Nanonetworks for Flexible Electronics

Abstract: Flexible electronics are attracting attention due to the increasing demand for lightweight, bendable devices that can conform to various surfaces, including human skin. Although indium tin oxide (ITO) is widely used for electrical interconnection in flexible electronics, its brittleness limits its durability under repeated bending. In this study, we introduce platinum (Pt) nanonetworks as an alternative to ITO, offering superior electrical stability under intense and repeated bending conditions. Electrically interconnected Pt nanonetworks, with an average thickness below 50 nm, are fabricated on polyimide (PI) substrates through an atmospheric treatment that promotes nanophase separation in thin deposition films of a platinum-cerium (Pt-Ce) alloy, creating a nanotexture of Pt and insulating cerium dioxide (CeO2). The resulting Pt nanonetworks on PI exhibit high mechanical flexibility, maintaining a sheet resistance of approximately 2.76 kohm/sq even after 1000 bending cycles at varying diameters, down to 1.5 mm. Detailed characterization reveals critical temperature and time thresholds in the atmospheric treatment necessary to form interconnected Pt nanonetworks on solid surfaces: interconnected nanonetworks form at lower temperatures and shorter treatment times, while higher temperatures and longer treatments lead to disconnected Pt nanoislands. LCR (Inductance, Capacitance, and Resistance) measurements further show that the interconnected Pt nanonetworks exhibit inductor-like electrical responses, while disconnected Pt nanoislands display capacitor-like behavior.