The invention concerns a method for depositing a thin polymer film on a substrate for functionalizing the surface of said substrate, comprising a step which consists in electrohydrodynamic spraying of a polymerizable precursor towards the substrate so as to produce an electrostatic deposition of electrically charged droplets of said precursor and form the thin film on the surface by polymerizing the droplets. The method is characterized in that it further comprises a step for causing the excited species to interact with the droplets of the sprayed precursor, thereby promoting the polymerization reactions of said precursor. The invention also concerns a device for implementing the method, in particular for depositing a thin polymer film on a moving substrate-film.