Seeds triggered massive synthesis and multi-step room temperature post-processing of silver nanoink—application for paper electronics

Paper electronics based on ink-jet printing has become a promising technology for building new concepts of flexible and three dimensional (3D) electronic circuits and devices in a simple, cost-effective and untraditional way. In this paper, we focus on the development of massive silver nanoink syntheses and room temperature post-processing methods to meet the particular technical features of paper electronics. We firstly proposed a seed triggered synthesis method to achieve uniform silver nanoparticles without the existence of large nanostructures. Such a silver nanoparticle solution can be easily centrifuged to nanoink at a relatively low speed. Then we showed that the electric conductivities of the printed silver tracks can be improved significantly by a multi-step room temperature post-processing (MRTP) method including organic solution washing, white LED irradiation and electroless deposition in sequence. Conductivities of up to 17% of that of bulk silver can be achieved which is nearly 2 times that of the printed silver tracks treated by a conventional heating process at 120 °C for a long time. Moreover, by combining together with 3D paper folding art, we systematically investigated the electrical performances of the printed circuits associated with the printing uniformity, mechanical flexibility and strain sensitivity. These overall characteristics of the room temperature treated printing technology show great potential for the development of innovative 3D electronic products in the future.