High-throughput and low-temperature processing of high-performance nanomaterial inks is an important technical challenge for large-area, flexible printed electronics. In this report, we demonstrate nitrocellulose as an exothermic binder for photonic annealing of conductive graphene inks, leveraging the rapid decomposition kinetics and built-in energy of nitrocellulose to enable versatile process integration. This strategy results in superlative electrical properties that are comparable to extended thermal annealing at 350 °C, using a pulsed light process that is compatible with thermally sensitive substrates. The resulting porous microstructure and broad liquid-phase patterning compatibility are exploited for printed graphene microsupercapacitors on paper-based substrates.

Phase inversion is demonstrated as an effective method for engineering the microstructure of graphene films by exploiting the well-defined solubility characteristics of polymer dispersants. Drying of a tailored phase inversion ink containing a nonvolatile nonsolvent leads to gelation and subsequent pore formation, providing a promising strategy to tailor the porosity of the resulting graphene films. Graphene films with tunable porosity and electrical conductivity ranging from ∼1000 to ∼22 000 S/m are fabricated by this method. Moreover, this dry phase inversion technique is compatible with conventional coating and printing methods, allowing direct ink writing of porous graphene microsupercapacitor electrodes for energy storage applications. Overall, this method provides a straightforward and versatile strategy for engineering the microstructure of solution-processed nanomaterials.