R = TIPS or TES R’ = F or CN

1. R R’ R’ R Organic semiconductors: exciton and charge carrier dynamics on macroscopic and microscopic levelsOksanaOstroverkhova, Oregon State University, DMR 0748671 (a) • Our work explores optoelectronic properties of small-molecular weight organic semiconductors from macroscopic (thin films) to microscopic (single-molecule) levels. • This year’s highlights include: • In functionalized anthradithiophene (ADT) thin films (macroscopic level), we: • Established relationships between exciton and charge carrier dynamics • Fully characterized a process of aggregate formation and associated changes in optoelectronic properties • Established mechanisms of energy transfer in ADT mixtures and its effect on optoelectronic properties • On the single-molecule (microscopic) level, we: • Demonstrated that ADT molecules can be imaged in various media on a single-molecule level and exhibit high fluorescence and photobleaching quantum yields R = TIPS or TES R’ = F or CN (b) (c) (d) (e) Figure: ADT derivatives under study (top left). (a) Photocurrent as a function of aggregate content in thin films. (b) and (c): PL and transient photoconductive properties of ADT film as a function of temperature. (d) and (e): Effect of FRET on PL and transient photoconductive properties of ADT mixtures. A. D. Platt et al., Ch.15 in Organic Thin Films for Photonic Applications, ACS Symp. Series 1039, 211-227 (2010), W. E. B. Shepherd et al., Proc. of SPIE7599, 75990R (2010), O. Ostroverkhovaet al., in Advances in Lasers and Electro-Optics, Intech , pp.1-32 (2010).

2. Involvement of undergraduate and high-school students in research and development of research instrumentation and softwareOksanaOstroverkhova, Oregon State University, DMR 0748671 #0748671 Undergraduate students, including under-represented women students, are actively involved in both research and educational activities carried out by our group. Six undergraduate students (two female) and a female high school student were involved in the project this year. Currently, Garrett Banton (senior, nuclear engineering major) and Kyle Williams (senior, physics major) perform experiments in and are developing image analysis software for single-molecule microscopy. AfinaNeunzert (sophomore, physics major) and Keith Schaefer (senior, physics major) explore time-resolved pump-probe spectroscopy and wavelength-dependent photoconductive gain, respectively, of organic semiconducting films. Hayley Sargent ( formerly high school researcher, now freshman, physics major) characterizes optical and fluorescent properties of new organic molecules. Garrett, Kyle, and Hayley (Afina and Keith) are working under the supervision of a graduate student Whitney Shepherd (Mark Kendrick). The PI is developing a novel graduate-level course on Nanoscience and Nanotechnology, which will be launched in Fall 2010. Whitney is checking Afina’s alignment of a Ti:Sapphire laser for time-resolved spectroscopy of ADT organic semiconducting films Left: Mark and Keith are measuring optoelectronic characteristics of organic thin films. Right: Kyle and Garrett are imaging ADT single molecules to test software they developed which incorporates both wide-field and confocal single-molecule fluorescence imaging, followed by statistical data analysis