The T-BAG: A novel method for the formation of self-assembled monolayers on metal oxide surfaces

A new method is described to prepare strongly bonded, compact monolayer films of alkyl- or arylphosphonates on a multitude of surfaces: the native oxides of metals. This method is applicable to many different metal or alloy substrates, and is illustrated for the silicon native oxide and indium tin oxide. Films are densely packed and are chemically bonded to the surface. Direct gravimetric analysis by a novel technique shows surface coverages in the film that correspond to molecular packing close to the crystallographic limit. AFM shows homogeneous SAMs are formed over large distances (mm scale) and with tilt angles for molecular components to be from 0° to 40° from vertical for aryl- and alkylphosphonate films, respectively. The use of these films for further functionalization of metal surfaces is shown. In addition, films of alpha-quarterthiophene-2-phosphonate on the surface of indium tin oxide doped with tetrafluorotetracyanoquinodimethane are shown to dramatically increase the performance of organic light emitting diodes where these doped films are used as the anode.