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1. R R’ R’ R Organic semiconductors: exciton and charge carrier dynamics on macroscopic and microscopic levelsOksana Ostroverkhova, Oregon State University, DMR 0748671 hn Our work explores optoelectronic properties of small-molecular weight organic semiconductors from macroscopic (thin films) to microscopic (single-molecule) levels. This year’s highlights are: 1) We discovered highly photoluminescent and photoconductive solution-processable ADT derivatives whose properties in thin films can be effectively manipulated by introducing guest molecules. By controlling the competition between charge and energy transfer in host -guest composites, desired optoelectronic properties can be obtained and optimized for specific applications. 2) We demonstrated that the ADT molecules can be imaged on a single-molecule level, exhibiting performance comparable to best fluorophores for single-molecule spectroscopy. This opens up possibilities to use ADT molecules as nanoprobes of conduction in organic semiconductor films and establish relationships between microscopic and macroscopic properties. (a) (b) R = TIPS or TES R’ = F or CN (c) (d) (e) Fluorescence of ADT single molecule Figure: ADT derivatives under study (middle). (a) Geometry for photoconductivity measurements. (b) and (c): Transient photoconductive and PL properties of ADT mixtures, respectively. (d) and (e): Fluorescent properties of ADT single molecules. J. Day et al., J. Appl. Phys. 105, 103703 (2009); J. Day et al., Appl. Phys. Lett.94, 013306 (2009); A. D. Platt et al., J. Phys. Chem. C113, 14006 (2009); O. Ostroverkhova et al., Proc. of SPIE7413, 7413-10 (2009)

2. Involvement of undergraduate students in the development of research instrumentation and web-based educational tutorialsOksana Ostroverkhova, Oregon State University, DMR 0748671 Undergraduate students, including under-represented women students, are actively involved in both research and educational activities carried out by our group. At least three undergraduate students are involved in the project every year. Currently, Garrett Banton (a junior majoring in nuclear engineering) performs experiments in and is developing image analysis software for wide-field single-molecule microscopy. Jessica Gifford (a junior majoring in physics) is calibrating our new confocal microscopy system. Jessica and Garrett are working under the supervision of a graduate student Whitney Shepherd. Another undergraduate student, Tom Gilray (a senior majoring in computer science), is developing web-based tutorials for effective dissemination of basic principles and frontiers of research in the area of organic optoelectronic materials. Our first tutorial, which provides an overview of photorefractive organic materials and their physics and applications is available at the link below: Whitney is checking Garrett’s and Jessica’s progress in calibrating experimental setup for single-molecule fluorescence spectroscopy Tom is demonstrating his web-based tutorial on organic photorefractives http://www.physics.orst.edu/~ostroveo/research/resources/tutorials/Photorefractives_tutorial/index.html