Laser assisted reduction of printed GO films and traces

Non-conductive graphene oxide (GO) particles (70% carbon, 30% oxygen) synthesized directly from inexpensive graphite powders are hydrophilic and can be dispersed homogeneously in water based solutions. In this study, thin film electrode traces are produced from a GO aqueous suspension using a commercially available inkjet printer. Once deposited on the functionalized substrate the printed film is thermally annealed to remove excess water and harden the material. The electrical conductivity of the high resistance (>10MΩ) annealed film is increased through the removal of oxygen molecules using a focused 775nm, 120fs pulsed laser. The electrical properties of select target areas on the thermally reduced graphene oxide (rGO) film can be tuned by adjusting the laser power, material feed rate, and the number of passes that the beam makes over the target surface. Experiments demonstrate that the rGO trace can be modified over a wide range of sheet resistance values (1MΩ to 2kΩ) for a ~1μm thick film. The proposed fabrication method can also be used to create a variety of resistive and semiconductor components on printed thin films, conductive electrodes and micro-circuit traces.