Conductive Inks Based on Melamine Intercalated Graphene Nanosheets for Inkjet Printed Flexible Electronics

With the growing number of flexible electronics applications, environmentally benign ways of mass-producing graphene electronics are sought. In this study, we present a scalable mechanochemical route for the exfoliation of graphite in a planetary ball mill with melamine to form melamine-intercalated graphene nanosheets (M-GNS). M-GNS morphology was evaluated, revealing small particles, down to 14 nm in diameter and 0.4 nm thick. The M-GNS were used as a functional material in the formulation of an inkjet-printable conductive ink, based on green solvents: water, ethanol, and ethylene glycol. The ink satisfied restrictions regarding stability and nanoparticle size; in addition, it was successfully inkjet printed on plastic sheets. Thermal and photonic post-print processing were evaluated as a means of reducing the electrical resistance of the printed features. Minimal sheet resistance values (5 k ohm/sq for 10 printed layers and 626 ohm/sq for 20 printed layers) were obtained on polyimide sheets, after thermal annealing for 1 h at 400 degrees C and a subsequent single intense pulsed light flash. Lastly, a proof-of-concept simple flexible printed circuit consisting of a battery-powered LED was realized. The demonstrated approach presents an environmentally friendly alternative to mass-producing graphene-based printed flexible electronics.

Automated summary

In this study, a scalable mechanochemical method for mass-producing graphene electronics was presented using melamine to exfoliate graphite in a planetary ball mill. The resulting melamine-intercalated graphene nanosheets (M-GNS) were used to formulate an inkjet-printable conductive ink and post-processing techniques were used to reduce electrical resistance. A simple flexible printed circuit consisting of a battery-powered LED was successfully realized. This study offers an environmentally friendly alternative for mass-producing graphene-based printed flexible electronics.