  The self-assembly of a single layer of organic molecules on a substrate is a
powerful strategy to modify surfaces and interfacial properties. The detailed
interplay of molecule-to-substrate and molecule-molecule interactions are
crucial for the preparation of stable and uniform monomolecular coatings.
Thiolates, silanes, phosphonates and carboxylates are widely used head-groups
to link organic molecules to specific surfaces study we show that self-assembly
of stable and highly compact monolayers of perfluorocarbons. Remarkably, the
lowest ever reported surface energy of 2.6 mJ m-2 was measured for a
perfluorododecyl iodide monolayer on a silicon nitride substrate. As a
convenient, flexible and simple method, the self-assembly of halogen-bond
driven perfluorocarbon monolayers is compatible with several applications,
ranging from biosensing to electronics and microfluidics. Compared to other
methods used to functionalise surfaces and interfaces, our procedure offers the
unique advantage to work with extremely inert perfluorinated solvents. We
demonstrate that surfaces commonly unstable in contact with many common organic
solvents, such as organic-inorganic perovskites, can be functionalized via
halogen bonding.
