Electroless Functionalization of Silver Films by Its Molecular Doping

We present a methodology which by far extends the potential applications of thin conductive silver films achieved by an electroless molecular doping process of the metal with any of the endless functional molecules that the large library of organic molecules offer. The resulting metallic films within which the molecule is entrapped-molecule@Ag-carry both the classical chemical and physical properties of silver films, as well as the function of the entrapped molecule. Raman measurements of the organic molecules from within the silver films provide the first spectroscopic observations from within silver, and clearly show that entrapment, a three-dimensional process, and adsorption, a two-dimensional process, on silver films are distinctly different processes. Three organic molecules, the cationic Neutral red, the anionic Congo red, and the antibacterial agent chlorhexidine digluconate (CH), were used to demonstrate the generality of this method for various types of molecules. We studied the sensitivity of the film conductivity to the type of the molecule entrapped within the film, to its concentration, and to temperature. Dual functionality was demonstrated with CH@Ag films, which are both conductive and have prolonged and high antibacterial activity, a combination of properties that has been unknown so far.