  Supramolecular self-assembly at the solid-solid interface enables the
deposition and monolayer formation of insoluble organic semiconductors under
ambient conditions. The underlying process, termed as the Organic Solid-Solid
Wetting Deposition (OSWD), generates two-dimensional adsorbates directly from
dispersed three-dimensional organic crystals. This straightforward process has
important implications in various fields of research and technology, such as in
the domains of low-dimensional crystal engineering, the chemical doping and
band-gap engineering of graphene, and in the area of field-effect transistor
fabrication. However, till date, lack of an in-depth understanding of the
physico-chemical basis of the OSWD prevented the identification of important
parameters, essential to achieve a better control of the growth of monolayers
and supramolecular assemblies with defined structures, sizes, and coverage
areas. Here we propose a detailed model for the OSWD, derived from experimental
and theoretical results that have been acquired by using the organic
semiconductor quinacridone as an example system. The model reveals the vital
role of the zeta potential and includes Casimir-like fluctuation-induced forces
and the effect of dewetting in hydrophobic nano-confinements. Based on our
results, the OSWD of insoluble organic molecules can hence be applied to
environmental friendly and low-cost dispersing agents, such as water. In
addition, the model substantially enhances the ability to control the OSWD in
terms of adsorbate structure and substrate coverage.
