Stable heating performance of carbon nanotube/silver nanowire transparent heaters

A flexible silver nanowire transparent heater (AgNW TH) was recently reported. However, the fabrication of AgNW THs that are durable over the long term is an important concern due to nanowire thermal instability. In this work, a thin AgNW film was coated with a dense single-walled carbon nanotube (SWCNT) film on glass and polyimide (PI) substrates. This simple hybrid heater was evaluated for heater performance and long-term working stability. The AgNW TH dried in air was unstable and failed more rapidly at elevated temperatures under Joule heating than that dried in vacuum. The AgNW TH had the same temperature limit irrespective of nanowire coating density due to the low melting point of AgNWs. The SWCNT/AgNW TH displayed a higher heating temperature and longer working stability than the AgNW TH. Based on thermoreflectance imaging and considering a power balance model, the improved thermal stability of the hybrid heater is attributed to thermal uniformity, in turn related to fast heat dissipation via heat transfer pathways of the dense SWCNT film, which delayed deformation and disconnection of the AgNWs. This simple hybrid structure could enhance the long-term working stability of AgNW-based THs in a wide range of practical applications.