February 15, 2017
Adrienne D. Stiff-Roberts Duke University Associate Professor of Electrical and Computer Engineering “Organic and Hybrid Organic-Inorganic Thin Film Deposition by Resonant Infrared, Matrix-Assisted
Pulsed Laser Evaporation” 4:10 PM, 134 Featheringill Hall Refreshments served at 3:45
Abstract
Over the past fifteen years, matrix-assisted pulsed laser evaporation (MAPLE) has been developed to deposit organic thin films, inorganic nanoparticles, and hybrid organic-inorganic nanocomposites. One variation of the MAPLE technique, resonant infrared matrix-assisted pulsed laser evaporation (RIR-MAPLE), reduces the laser energy (e.g., Er:YAG laser ~2.94μm peak wavelength) in order to minimize polymer degradation. In addition, because the frequency of the IR laser energy is resonant with OH bond vibrational modes in water, a frozen emulsion (comprising a mixture of the guest material dissolved in an organic solvent and water) is used as the target. Therefore, the unique advantage of emulsion-based RIR-MAPLE is that most of the energy from the IR laser is absorbed by water in the frozen emulsion, which evaporates and gently transfers the guest material to the substrate with minimal solvent exposure and degradation.
In the case of hybrid organic-inorganic nanocomposites, inorganic nanoparticles are embedded in a polymer matrix to achieve specific materials properties or functionality; however, nanoparticles that are mixed with a polymer in solution tend to aggregate due to a polarity difference with polymers. In contrast, RIR-MAPLE is fundamentally different from solution processing and reduces nanoparticle phase segregation by eliminating the need to co-dissolve nanoparticles and polymers into a single common solvent; and by depositing the nanoparticles and polymers in a relatively dry state.
We will demonstrate the capability of RIR-MAPLE to deposit continuous nanoparticle films with the same optical properties as nanoparticles in solution and to minimize nanoparticle phase segregation in hybrid films. We will also demonstrate hybrid organic-inorganic thin films deposited by RIR-MAPLE for application to solar cells.
Bio
Adrienne D. Stiff-Roberts is Associate Professor of Electrical and Computer Engineering at Duke University, and she currently serves as the Education Director of the Research Triangle Materials Research Science and Engineering Center (RT-MRSEC). Her current research interests include polymer, nanoparticle, and organic/inorganic hybrid nanocomposite thin film deposition by resonant-infrared matrix-assisted pulsed laser evaporation (RIR-MAPLE); materials characterization of organic and hybrid nanocomposite thin films; and the design, fabrication, and characterization of organic-based devices, especially infrared photodetectors, photovoltaic solar cells, and multi-functional sensors.
Dr. Stiff-Roberts received both the B.S. degree in physics from Spelman College and the B.E.E. degree in electrical engineering from the Georgia Institute of Technology in 1999. She received an M.S.E. in electrical engineering and a Ph.D. in applied physics in 2001 and 2004, respectively, from the University of Michigan, Ann Arbor, where she investigated high-temperature quantum dot infrared photodetectors grown by molecular beam epitaxy.
Dr. Stiff-Roberts has authored or co-authored over 90 peer-reviewed journal articles, magazine articles, book chapters, conference proceedings, and invited talks. She has served as PI or co-PI on research grants from NSF, ONR, AFOSR, and ARO, as well as user grants from ORNL. Dr. Stiff-Roberts is on the Editorial Board of Scientific Reports (Nature Publishing Group) and she is past Chapter Chair of the IEEE Photonics Society, Eastern North Carolina Section (2006-2010).
Dr. Stiff-Roberts received the David and Lucile Packard Foundation Graduate Scholars Fellowship and the AT&T Labs Fellowship Program Grant from 1999-2004. She is a recipient of the National Science Foundation CAREER Award (2006), the Office of Naval Research Young Investigator Award (2007), the IEEE Early Career Award in Nanotechnology of the Nanotechnology Council (2009), and the Presidential Early Career Award for Scientists and Engineers (2009). She is a member of Phi Beta Kappa, Sigma Pi Sigma, the Materials Research Society, the National Society of Black Physicists, the American Physical Society, the American Chemical Society, and she is a senior member of IEEE.