Interface modified flexible printed conductive films via Ag 2 O nanoparticle decorated Ag flake inks.

A new approach to stable, low resistance inexpensive printed flexible conductive inks is proposed. Silver ink has been studied extensively and commercialized for applications in printed electronics due to the inherent high conductivity and stability of silver, even in particulate-based percolation networks processed at temperatures compatible with low cost polymer films such as polyethylene terephthalate (PET). Recent interest in flexible and even stretchable circuits, however, has presented new challenges for particle-based inks as mechanical strains can result in the opening of critical particle-to-particle contacts. Here we report a facile, low cost method for the single step synthesis of stable, printable nanoscale Ag2 O-decorated Ag flake inks which can be converted to highly conductive Ag films at 150°C curing temperature without the use of limited shelf life organometallics or low metal loading metal nanoparticles to modify the interface between silver flakes. Analysis indicates that decoration of Ag flakes with Ag2 O NPs improves the conductivity and flexibility of printed silver films by forming bridging interconnections between Ag flakes after low temperature reduction of the Ag2 O NPs. In this work, printed nano-decorated silver conductors with starting oxide to metal weight ratios of 5:95 exhibited lateral resistivities lower than 1.5×10-5 Ω cm, which was 35% less than films derived from undecorated Ag flake inks of the same total Ag loading and binder system. This resistivity difference increased to 45% after cyclic bend testing showing increased resilience to repeated flexing for the nano-decorated inks.