Organic Semiconductors and Metals

Organic electronic materials are of interest due to both the technological promise of carbon-based devices and to the scientific challenge posed by these materials to our understanding of basic physical processes in complex solids. Despite the importance of semiconducting organic materials, there have been few studies of their valence band electronic structure using modern synchrotron radiation-based spectroscopic methods.  In part this is due to the difficulty in preparing clean samples for study, but also due to the severe x-ray radiation beam damage suffered by these materials.  We are undertaking a comprehensive synchrotron radiation-based soft x-ray spectroscopic study of a variety of thin film organic electronic materials, including semiconductors, metals, and molecular magnets.  The organic films are grown in-situ, with proper attention paid to minimizing beam damage effects.  The films are grown in a custom built organic molecular beam epitaxy chamber attached to the spectrometer chamber at a soft x-ray undulator beamline at the National Synchrotron Light Source.  Information is obtained on the element and site specific valence band partial density of states, band dispersions, chemical state, and orbital bonding in the films.  Our work on novel organic metals is undertaken in collaboration with Professor Linda Doerrer in the BU Department of Chemistry, whose group synthesizes the materials.