Ink properties. (a) TGA and DTG curves (inset, OSC ink). (b) Variation of resistivity sintered at different temperatures for different times. (c) XRD pattern of sintered OSC ink with a solid content of 20 wt.% (the inset shows the top-view SEM image of the conductive film). (d) Lateral view of the SEM image of the silver film sintered at 120°C for 30 s (dimethylformamide was used as reduction agent in the formula).