Highly conductive ag nanoparticulate films induced by movable rapid thermal annealing applicable to roll-to-roll processing

A post-treatment process for metallic nanoparticle-based films using a movable halogen lamp is proposed to improve the microstructural density and the electrical conductivity. An annealing system that conceptually simplifies roll-to-roll processing was constructed, and the halogen lamp used as a heating source was designed to move instead of the substrate. When the liquid inkjet-printed film was annealed at a high heating rate, high density and near-bulk resistivity (2.64 cm) were obtained. The microstructure of the nanoparticle-based films contained fewer internal and interfacial pores and larger grains after the new annealing technique, compared with those produced by conventional furnace annealing. This high-density microstructure is due to the high heating rate, which causes the abrupt decomposition of the organic shell at higher temperatures than the low heating rate and induces densification of the nanoparticle-based films. The new process is much simpler and faster than the conventional furnace process. In addition, this method can be applied to thick inkjet-printed films annealing.