Surface morphology and current-voltage characteristics of monolayer Langmuir-Blodgett films of conjugated organic molecules

The surface morphology of W-light polymerized monolayer Langmuir-Blodgett f ilms of 10-12 pentacosadyinoic acid (12-8 diacetylene) deposited on flat go ld substrates was imaged by atomic force microscopy. Current-voltage charac teristics of the monolayer film was measured by using the tip of a scanning tunneling microscope at individual points on the film surface and compared to the ones measured on the bare gold substrate. The measured current-volt age characteristics are correlated and discussed with the expectation of th e Au Fermi level of the substrate, Pt/Ir Fermi level of the tip and the hig her occupied molecular orbital/lower unoccupied molecular orbital energy le vels of the polydiacetylene molecule. (C) 2000 Elsevier Science B.V. All ri ghts reserved.