A low temperature and air-sinterable copper–diamine complex-based metal organic decomposition ink for printed electronics

Conductive copper patterns are usually heated in vacuum, inert gas or reducing atmosphere to avoid the oxidation of copper for printed electronics applications. Here, we report a formulation of metal organic decomposition copper ink and obtained conductive copper films by heating the ink in air at low temperatures using diamine as the complexing agent without other additions. The complexing of diamine with the copper formate tetrahydrate precursor lowers the thermal decomposition temperature of the ink, promotes the densification of the film and prevents the oxidation of copper by consuming absorbed oxygen during the heating process. The copper films using 1,2-diaminopropane as the complexing agent showed a low resistivity of 1.8 × 10−5 Ω cm after heating at 180 °C for 1 min in air. The pen-writing copper patterns showed a metal copper luster and great adhesion on a PI substrate.