  Hypothesis: Contact-line motion upon drying of sessile droplet strongly
affects the solute transport and solvent evaporation profile. Hence, it should
have a strong impact on the deposit formation and might be responsible for
volcano-like, dome-like and at deposit morphologies.
  Experiments: A method based on a thin-film interference was used to track the
drop height profile and contact line motion during the drying. A diverse set of
drying scenarios was obtained by using inks with different solvent compositions
and by adjusting the substrate wetting properties. The experimental data was
compared to the predictions of phenomenological model.
  Findings: We highlight the essential role of contact-line mobility on the
deposit morphology of solution-based inks. A pinned contact line produces
exclusively ring-like deposits under normal conditions. On the contrary, drops
with a mobile contact line can produce ring-, at- or dome-like morphology. The
developed phenomenological model shows that the deposit morphology depends on
solvent evaporation profile, evolution of the drop radius relative to its
contact angle, and the ratio between initial and maximal (gelling) solute
concentration. These parameters can be adjusted by the ink solvent composition
and substrate wetting behaviour, which provides a way for deposition of uniform
and at deposits via inkjet printing.

Fluid Dynamics;Chemical Physics