Elaboration and Electrical Characterization of Langmuir−Blodgett Films of 4-Mercaptoaniline Functionalized Platinum Nanoparticles

Abstract

The elaboration of Langmuir−Blodgett (LB) films of platinum nanoparticles is described. In contrast to most of the previously reported studies that concern metallic particles capped with long alkyl chains, the aggregates involved in this work bear external polar amine functions. The area per particle is consistent with the formation of essentially monoparticle thick Langmuir films at low surface pressures. Pure films of these particles are efficiently transferred horizontally whereas conventional vertical deposition can be used with mixed films containing added fatty acid. The LB films were characterized by IR spectroscopy, AFM, STEM, and X-ray diffraction. The electrical properties of the ultrathin materials based on pure films and mixed films were investigated. The nonmetallic conductivity is characterized by an activation energy of ≈80 meV and lies in the range 10-2 to 10-3 S·cm-1. The material exhibits good long-term electrical stability. Finally, it is shown that the fatty acid can be washed out from mixed films without dramatic effects on the conductivity of the material.