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Full-Text Articles in Physics

Influence Of Functionalized Fullerene Structure On Polymer Photovoltaic Degradation, Brian H. Johnson, Enaanake Allagoa, Robert L. Thomas, Gregory Stettler, Marianne Wallis, Justn H. Peel, Thorsteinn Adalsteinsson, Brian J. Mcnelis, Richard P. Barber Jr. Mar 2010

Influence Of Functionalized Fullerene Structure On Polymer Photovoltaic Degradation, Brian H. Johnson, Enaanake Allagoa, Robert L. Thomas, Gregory Stettler, Marianne Wallis, Justn H. Peel, Thorsteinn Adalsteinsson, Brian J. Mcnelis, Richard P. Barber Jr.

Physics

The time dependence of device performance has been measured for photocells using blends containing the conjugated polymer, poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) with two different functionalized C60 electron acceptor molecules: commercially available [6,6]-phenyl C61 butyric acid methyl ester (PCBM) or [6,6]-phenyl C61 butyric acid octadecyl ester (PCBOD) produced in this laboratory. Performance was characterized by the short-circuit current output of the devices, with the time dependence of PCBM samples typically degrading exponentially. Variations in the characteristic lifetime of the devices were observed to depend on the molar fraction of the electron acceptor molecules (calculated with respect to the MEH-PPV monomer fraction). In comparison …


Study Of The Photoinduced Surface Relief Modulation In Photopolymers Caused By Illumination With A Gaussian Beam Of Light, Tzvetanka Babeva, Dana Mackey, Suzanne Martin, Izabela Naydenova, Vincent Toal Jan 2010

Study Of The Photoinduced Surface Relief Modulation In Photopolymers Caused By Illumination With A Gaussian Beam Of Light, Tzvetanka Babeva, Dana Mackey, Suzanne Martin, Izabela Naydenova, Vincent Toal

Articles

The formation of surface relief profile in photopolymerisable systems when illuminated with a focused beam of light is simulated numerically using a two-way diffusion model that takes account both for monomer and short polymer chains diffusion. The concentration and spatial distribution dynamics of monomer and short and long polymer chains are calculated. The surface profile is obtained from calculated components concentrations considering different densities of monomer and polymer. The influence of the illumination time, intensity and spot diameter on the surface profiles dynamics is discussed. A good agreement between the calculated and the experimentally measured profiles is observed thus demonstrating …


Structural, Electronic, Vibrational And Thermodynamical Properties Of Surfaces And Nanoparticles, Handan Yildirim Jan 2010

Structural, Electronic, Vibrational And Thermodynamical Properties Of Surfaces And Nanoparticles, Handan Yildirim

Electronic Theses and Dissertations

The main focus of the thesis is to have better understanding of the atomic and electronic structures, vibrational dynamics and thermodynamics of metallic surfaces and bi-metallic nanoparticles (NPs) via a multi-scale simulational approach. The research presented here involves the study of the physical and chemical properties of metallic surfaces and NPs that are useful to determine their functionality in building novel materials. The study follows the 'bottom-up' approach for which the knowledge gathered at the scale of atoms and NPs serves as a base to build, at the macroscopic scale, materials with desired physical and chemical properties. We use a …