Flexible and Transparent Electrothermal Film Heaters Based on Graphene Materials

High-performance and novel graphene-based electrothermal films are fabricated through a simple yet versatile solution process. Their electrothermal performances are studied in terms of applied voltage, heating rate, and input power density. The electrothermal films annealed at high temperature show high transmittance and display good heating performance. For example, the graphene-based film annealed at 800 degrees C, which shows transmittance of over 80 parts per thousand at 550 nm, can reach a saturated temperature of up to 42 degrees C when 60 V is applied for 2 min. Graphene-based films annealed at 900 and 1000 degrees C can exhibit high steady-state temperatures of 150 and 206 degrees C under an applied voltage of 60 V with a maximum heating rate of over 7 degrees C s-1. For flexible heating films patterned on polyimide, a steady-state temperature of 72 degrees C could be reached in less than 10 s with a maximum heating rate exceeding 16 degrees C s-1 at 60 V. These excellent results, combined with the high chemical stability and mechanical flexibility of graphene, indicate that graphene-based electrothermal elements hold great promise for many practical applications, such as defrosting and antifogging devices.