Effect of laser power on conductivity and morphology of silver nanoparticle thin films prepared by a laser assisted electrospray deposition method

Silver nanoparticle-based electrodes were studied extensively in recent years as an electrode material for wearable and flexible electronics due to their stability and conductivity. A wet chemical deposition technique is considered as a low-cost scalable technique. The current wet chemical-based nanoparticle deposition techniques include electrospray deposition, drop casting, spin coating, and the inkjet printing process. These techniques generally require a separate postdeposition annealing step. This can be a problem for substrates with a low melting point. In addition, some of the above-mentioned methods require physical contact, which increases the probability of cross-contamination. In this research, we present a technique that combines electrospray and laser radiation to deposit and sinter nanoparticles simultaneously on a rigid or flexible substrate. In this process, the microdroplets of aqueous silver nanoparticle suspension ejected in what is known as the microdripping mode from a metallic capillary nozzle, which can be controlled by an electric potential. A conical hollow laser beam is used to vaporize the liquid and sinter the nanoparticles at desired locations on a substrate. This is a promising technique compared to the traditional methods to fabricate conductive micropatterns due to its simplified one step deposition, suppressed cross-contamination, and applicability to various surfaces. Thin-film micropatterns of silver nanoparticles were fabricated using a Nd:YAG laser with powers from 5 to 13 W. The correlation between the grain size distribution, composition, and electrical resistivity was studied using a scanning electron microscope, energy-dispersive x ray, and four-point probe analysis. The results are comparable to the conventional thermal sintering method.