Impaction of thin films from polar solvent Si/SiOx nanoparticle inks

Abstract

Impaction techniques have so far been efficiently used for formation of films from nanoparticles when coupled to synthetic process. However, this approach limits the choice of shapes and compositions of particles, so techniques of impaction of ready-made particles are desirable. To this end, the use of nanoparticle inks as a source of solid material is first described in this paper. The films are cast from dispersions of polar solvent-susceptible Si/SiOx nanoparticles. Water, ethanol, and acetonitrile are studied for solvents, and the latter two are shown to be suitable, as they possess lower surface tension and lower boiling points. Microscopically uniform films of nanoparticles are formed when aerosol and substrate are heated, with density of films approaching 40% of that of the bulk material. Higher stagnation pressure is beneficial for deposition, while further heating of the aerosol beyond the solvent evaporation can cause oligomerization of the solvent. Deposition of dense films in subsonic part of the jet appears possible with the technique.