Improvement of electrical and mechanical properties of Ag nanoparticulate films by controlling the oxygen pressure

A new method to improve the electrical conductivity and elastic modulus of inkjet-printed Ag films by controlling the oxygen pressure during the annealing process (annealing under air after ramping under vacuum) is presented. Compared to the porous layer under the dense surface layer in conventional annealing, densification throughout the entire film was observed in the microstructure treated by oxygen pressure controlled annealing. The electrical resistivity and elastic modulus of Ag films annealed by this new process were 1.95 μ cm and 47 GPa, which are better than those by the conventional process (2.48 μ cm and 40 GPa). It was found that the remaining of capping molecules during the ramping in vacuum act as the inhibitor of grain evolution and retard the onset of grain growth at higher temperature, which begins by blowing air into the annealing atmosphere.