Described herein are molecular inks, methods for printing the molecular inks on flexible substrates, and methods for forming printed electronic elements, such as resistive heaters, force sensors, motion sensors, and devices that include these elements, such as force responsive conductive heaters. The methods include printing a molecular ink on a flexible substrate that is heated to 30° C. to 90° C. before and/or during the printing process and curing the substrate to produce a conductive pattern thereon. The molecular inks generally include a particle-fee metal-complex composition formulated from at least one metal complex and a solvent, and optionally, a conductive filler material, and/or surfactant.