Effect of photonic flash annealing with subsequent compression rolling on the topography, microstructure and electrical performance of carbon-based inks

Binders used in screen-printed carbon-based inks are typically non-conductive. Photonic annealing and subsequent compression rolling have therefore been employed to remove binder and consolidate the conductive particles. Using this method, screen-printable carbon inks containing graphite only, graphite nanoplatelets and a combination of graphite and carbon black were assessed. Photonic annealing leads to the degradation of the polymer binder separating the carbon morphologies, with subsequent compression rolling leading to significant reductions in print film thickness, roughness and improvements in particle orientation. Both processes lead to electrical performance enhancement for all printed inks assessed. The process was most effective for single graphitic morphologies with large gaps between conductors. These saw significant improvements, with reductions in electrical resistivity from 1.91 to 0.23 Ω cm for the graphite ink. The mixed carbon ink saw smaller but still significant improvements in print roughness and resistivity, from 0.037 to 0.019 Ω cm. Therefore, these postprocesses could widen the applications of common, low-cost carbon morphologies in screen printing inks.