Nickel-Based Inks for Flexible Electronics — A Review on Recent Trends

Abstract

Inkjet printing (IJP) is an efficient, simple, scalable and low-cost additive manufacturing technique for the deposition of functional materials on substrates used in flexible electronic devices, sensors, and light-emitting diodes to name a few. Nanoparticle ink, metal oxide decomposition (particle-free ink), polymer ink, and semiconductor ink are classifications of the inks used in IJP. Effective printing of the material is possible when the ink parameters (viscosity, particle size, surface tension) and its derived dimensionless quantities (Weber number, Reynolds’ number, and Ohnesorge number) fall within a desirable range. The formation of the coffee-ring effect during the post-printing process is one of the major concerns, which affects the morphology and electrical conductivity of the printed pattern. In this review, a summary of recent developments of Ni-based inks in terms of formulation, sintering and properties is presented, along with the effect of combining Ni with other materials such as NiO, Ag, Cu, Zn, Fe, carbon, and rare earth metals on the film properties. The precursors and solvents used for the Ni ink preparation, along with the additives and surfactants, have been presented to understand their impact on the film’s properties and develop a design to choose the ideal precursor–solvent pair. Finally, the challenges in formulating inks and the necessity to develop a model to optimize the choice of solvent/precursor are presented. The model would improve the selection of additives and precursors and reduce material wastage and enhance performance with fewer defects.