We report a novel method for the synthesis of a self-reducible (thermally reducible without a reducing atmosphere) and alcohol-soluble copper-based metal-organic decomposition (MOD) ink for printed electronics. Alcohol-solvent-based conductive inks are necessary for commercial printing processes such as reverse offset printing. We selected copper(II) formate as a precursor and alkanolamine (2-amino-2-methyl-1-propanol) as a ligand to make an alcohol-solvent-based conductive ink and to assist in the reduction reaction of copper(II) formate. In addition, a co-complexing agent (octylamine) and a sintering helper (hexanoic acid) were introduced to improve the metallic copper film. The specific resistivity of copper-based MOD ink (Cuf-AMP-OH ink) after heat treatment at 350 °C is 9.46 μΩ·cm, which is 5.5 times higher than the specific resistivity of bulk copper. A simple stamping transfer was conducted to demonstrate the potential of our ink for commercial printing processes.

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We study particle dynamics in drying colloidal solutions using the numerical simulation with discrete particle method (DPM). Simulations of two different systems were conducted; the drying dynamics of monodispersed and binary mixture of colloidal solution, and compared with those from the previous studies. In the monodispersed colloidal solution, the time evolution of particle concentration profile for varying Péclet number was simulated with the same initial particle concentration. In the binary colloidal solution, when the particle size ratio α is 3, three different stratification modes were observed varying Péclet number and initial particle concentration. By comparison, our method was in a good agreement with the existing methods. Additionally, because of the mesh-based Eulerian approach in our model, other various multi-physical phenomena, such as effect of thermal Marangoni or chemical reaction, can be included in an easy way. From the results, we expect that this work can provide a physical insight for predicting the quality of colloidal drying in a complicated situation.