Optimizing formulations of silver organic decomposition ink for producing highly-conductive features on flexible substrates: The case study of amines

Highly conductive silver patterns that can be cured at low temperatures were achieved by proper selection of the kinds of amines in the formulation of metal organic decomposition (MOD) ink. The inks were synthesized via a complexing reaction between silver tartrate and various amines in ethyl alcohol solvent. Four monoamines and two diamines with increased carbon chain lengths were used. The kinds of amines affected the thermal decomposition temperature of silver ink as well as the sheet resistance and microstructure of the obtained silver films significantly. The film from 1,2-diaminopropane ink showed the lowest resistance and uniform surface morphology among all the inks developed. The microstructural evolution of the cured silver films was well correlated with the formulations of the inks. The underlying mechanism was discussed. The ink formulations were further elaborated by proper selection of Ag/NH2 molar ratios. Highly conductive silver films with excellent flexible stability and great adhesion were achieved using optimized silver MOD inks.