Super-stretchable polymer-AgPdCu superlattice electrodes for high-performance wearable electronics

Abstract

Highly-stretchable and semi-transparent polytetrafluoroethylene (PTFE)/AgPdCu (APC)-PTFE-based superlattice electrodes were realized by alternately sputtering very thin APC-PTFE hybrid layers on a polyurethane (PU) substrate at room temperature. The electrical and mechanical properties of the superlattice electrodes were optimized by controlling the PTFE thickness and the number of layers of the stacked superlattice. The optimal PTFE/APC-PTFE/PTFE/APC-PTFE/PTFE superlattice electrode showed a sheet resistance of 8.5 Ohm/square and maintained a high conductivity, even at a strain of 100%. The outstanding mechanical stretchability of the superlattice electrode is attributed to the 3-dimensional conductive APC network structure in the PTFE polymer matrix . In addition, the external strain applied to the superlattice electrode led to a change in the optical transmittance that could be used for optical switching in stretchable electronics. The superlattice electrodes can be utilized to fabricate stretchable electroluminescent devices, stretchable thin film heaters, and wearable temperature sensors . This successful demonstration of stretchable devices that include highly stretchable superlattice electrodes demonstrated the feasibility of this manufacturing strategy for use in next-generation stretchable and wearable electronics . • Fabrication of highly conductive and stretchable metal-polymer 3D nanocomposites by continuous co-sputtering of polymer and metal target. • The number of stacked layers and thickness of the polymer and polymer-metal hybrid films were controlled to form an alternating superlattice structure. • The optimized electrode showed a sheet resistance of 8.5 Ohm/square, an average transmittance of 34.0% for visible light, and stretchability that reversibly maintained a high conductivity at up to 100% strain. • The optimized electrode was applied as stretchable thin-film heater, electroluminescent device, and wearable temperature sensor.