Fine tuning of inkjet printability parameters for NiO nanofilms fabrication

Nickel oxide (NiO) is a fascinating compound due to its potential use as electrocatalytic material and in many other applications. In several technological applications, the NiO is require as continue and homogeneous thin film. In the present work three water-based inks were formulated in order to analyze the effect of the presence of additives on their physicochemical properties and printability performance for the fabrication of NiO thin films by using inkjet printing technique. By means of integrated physicochemical analysis, the printability of the formulated inks was defined by a map in terms of Reynolds and Weber numbers. According to the obtained results, all the formulated inks are readily printable. The presence of additives in the respective inks reduced the contact angle value formed onto substrate surface favoring their wettability considerably. This characteristic influenced importantly on the interactions between the deposited droplets, requiring a smaller number of droplets for obtaining a homogeneous, continuous, and well-defined film. After optimization of parameters, NiO films with 1, 3 and 5 layers were inkjet-printed and sintering at 550 degrees C to obtain crystalline NiO phase characterized by the presence of nanoparticles with sizes of similar to 15 nm, film thickness from 90 to 190 nm and Ni2+/Ni3+ surface chemical states.