WFU Physics Colloquium

TITLE: Visualizing Disorder at Metal-Organic Interfaces

SPEAKER: Professor Dan Dougherty ,

TIME: Wednesday September 15, 2010 at 4:00 PM

PLACE: Room 101 Olin Physical Laboratory

Organic thin film devices have already entered the commercial electronics market in low power LED displays. They hold significant promise in the crucial area of low-cost solar to electric energy conversion [1]. They have also been reported to exhibit long range spin polarized electron transport that could be used for organic spintronic devices [2]. These important applications have placed significant demands on our ability to correlate the structure of organic thin films with device-relevant electronic properties. Often organic films in devices are amorphous, leading to serious complications in establishing these structure-function correlations.

I'll describe scanning tunneling microscopy experiments that directly visualize the unique disorder in the first layer of a prototype organic semiconductor, called Alq3, grown on single crystal metal substrates. In addition, local scanning tunneling spectroscopy experiments will be described that indicate the connection between structural disorder and the distribution of electronic transport states at the metal-organic interface. Finally, I'll discuss planned experiments to probe spin dependent electronic structure in this material using spin polarized scanning tunneling spectroscopy.

[1] Shaheen et al., MRS Bulletin 30, 10 (2005).

[2] Dediu et al., Nature Materials 8, 707 (2009).