▎ 摘　　要

The electric heaters used in wearable electronic devices require mechanical and thermal stability against deformation and flexibility. In this study, we fabricated a film heater by coating a flexible substrate with a network of silver nanowires coated with chemical-vapour-deposited graphene (denoted as GPonAgNWs) and observed the effect of the number of graphene layers on the heating performance and stability. As the number of graphene layers increased, the maximum temperature and bending cycles that the GPonAgNW network could withstand increased upon repeated bending deformation. Silver nanowire networks coated with two and four graphene layers could, respectively, withstand temperatures of 58 and 70 degrees C for 18,000 bending cycles at a strain of 15%, whereas a graphene-free silver nanowire network failed at 51 degrees C after 180 cycles. Moreover, a real-time analysis during cyclic bending deformation of the silver nanowire network coated with four-layer graphene showed a stable temperature variation within 2 degrees C despite the doubling of resistance for 180,000 cycles. Structural analysis and Monte Carlo simulation demonstrated that the graphene-induced reduction of the contact resistance between the two nanowires could suppress the hotspots generated at the contact, thereby providing an extended heater lifetime and stable heater performance in the GPonAgNW network. Thus, we suggest that flexible heaters made of GPonAgNW networks, exhibiting high reliability upon repeated deformation, can be used in wearable devices.