ABSTRACT
Joule heaters based on flexible thin films have attracted a significant amount of attention in both academia and the industry. However, it has been highly challenging to fabricate such heaters. In this study, a one-step laser induction method was proposed to prepare fluorine-doped laser-induced graphene (F-LIG) with stable and superhydrophobic properties by confining a 355 nm ultraviolet laser at the interface between the fluorinated ethylene propylene (FEP) film and polyimide (PI) film. The superhydrophobic properties of the F-LIG composite films could be attributed to the doping of fluorine elements and the laser-processed microstructures, which could be tuned by laser processing parameters. Based on the processed F-LIG films, Joule deicing heaters were developed and their deicing efficiencies are 7 times higher than that of the undoped LIG-based deicing heater. The method will provide new means and ideas to develop LIG-based flexible devices.
ABSTRACT
Laser-induced graphene (LIG) has emerged as a promising and versatile method for high-throughput graphene patterning; however, its full potential in creating complex structures and devices for practical applications is yet to be explored. In this study, an in-situ growing LIG process that enables to pattern superhydrophobic fluorine-doped graphene on fluorinated ethylene propylene (FEP)-coated polyimide (PI) is demonstrated. This method leverages on distinct spectral responses of FEP and PI during laser excitation to generate the environment preferentially for LIG formation, eliminating the need for multistep processes and specific atmospheres. The structured and water-repellant structures rendered by the spectral-tuned interfacial LIG process are suitable as the electrode for the construction of a flexible droplet-based electricity generator (DEG), which exhibits high power conversion efficiency, generating a peak power density of 47.5 W m-2 from the impact of a water droplet 105 µL from a height of 25 cm. Importantly, the device exhibits superior cyclability and operational stability under high humidity and various pH conditions. The facile process developed can be extended to realize various functional devices.
