Inkjet-printed lines with well-defined morphologies and low electrical resistance on repellent pore-structured polyimide films.

Polyimide films are the most promising substrates for use in printed electronics because of their high thermal stability. However, the high wettability of polyimide films by conductive inks often produces thin inkjet-printed lines with splashed and wavy boundaries, resulting in high electrical resistance of the lines. To overcome these disadvantages, we fabricated repellent pore structures composed of polyamideimide with high thermal stability on a polyimide film. Using this film, the inkjet-printed line thickness was increased without penetration of silver nanoparticles into the pore structures, thus resulting in very sharp edges without any splashing. This was because the repellent treatment restricted the spreading of the silver nanoparticles into the pore structures and the pore structures prevented ink splashing upon impact on the film. As a result, the electrical resistance of these lines decreased to one-fifth that of the lines on the pristine polyimide film. The inkjet printing of conductive inks onto repellent pore structures would contribute to the future of printed electronics because this technique enables printing closely packed line patterns while maintaining high conductivity within a limited space.