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Search Publications by: Andrew Herzing (Fed)

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Displaying 51 - 75 of 81

Substitutional Doping in Nanocrystal Superlattices

August 27, 2015
Author(s)
Aaron C. Johnston-Peck, Matteo Cargnello, Benjamin T. Diroll, Eric Wong, Bianca Datta, Divij Damodar, Vicky V. Doan-Nguyen, Andrew A. Herzing, Cherie R. Kagan, Christopher B. Murray

Real-time x-ray scattering studies of film formation in high performing small-molecule organic solar cells

May 23, 2015
Author(s)
Sebastian Engmann, Felicia A. Bokel, Andrew Herzing, Hyun W. Ro, Dean DeLongchamp, Lee J. Richter, Claudio Girotto, Bruno Caputo
We have studied the influence of the additive diiodoctane on the formation dynamics of high performance bulk heterojunction (BHJ) films based the small molecule donor 7,7'-(4,4bis(2- ethylhexyl)-4H-silolo[3,2-b:4,5-b']dithiophene-2,6-diyl)bis(6-fluoro-5-(5

In-situ Characterization of Polymer-Fullerene Bilayer Stability

January 8, 2015
Author(s)
Lee J. Richter, Regis J. Kline, Hyun Wook Ro, Chad R. Snyder, Andrew A. Herzing, Sebastian Engmann
A consensus is emerging that every phase present in a bulk heterojunction organic photovoltaic (OPV) device is not material pure. In general, there will exist at least one region characterized by a mixture of donor and acceptor. Significant insights into

Comparing Matched Polymer:Fullerene Solar Cells Made by Solution-Sequential Processing and Traditional Blend Casting: Nanoscale Structure and Device Performance

July 8, 2014
Author(s)
Andrew Herzing, Steven A. Hawks, Jordan C. Aguirre, Laura T. Schelhas, Robert Thompson, Rachel Huber, Amy Ferreira, Guangye Zhang, Robert A. Street, Sarah Tolbert, Benjamin Schwartz
Efficient bulk heterojunction (BHJ) solar cells based on polymer:fullerene photoactive layers can be created either by traditional blend casting (BC), where the components are mixed together in solution before being cast, or by solution-sequential

Comparison of atom probe compositional fidelity across thin film interfaces

January 1, 2014
Author(s)
Andrew Herzing, Justin G. Brons, Karen T. Henry, Ian M. Anderson, Gregory B. Thompson
A series of Fe/Ni and Ti/Nb multilayers with bilayer repeat distances of approximately 4 nm have been sputter-deposited onto n-doped Si [001] substrates. The films were focus ion beam milled into the required needle-shaped geometry for atom probe analysis

Microscopic investigation of Single-Wall Carbon Nanotube Uptake by Daphnia magna

December 18, 2013
Author(s)
Aaron Edgington, Elijah Petersen, Andrew Herzing, Apparao Rao, Stephen Klaine
The objectives of this study were to determine the absorption of single-wall carbon nanotubes (SWCNTs) across the gut epithelial cells in Daphnia magna and to determine if absorption was influenced by their surface functionalization. This project utilized

Size-Dependent Structural Distortions

January 7, 2013
Author(s)
Michael D. Anderson, Colby L. Heideman, Qiyin Lin, Mary Smeller, Robert S. Kokenyesi, Andrew Herzing, Ian M. Anderson, Douglas A. Keszler, Paul Zschack, David C. Johnson
Recently we reported that intergrowth compounds [(MSe)1+y]m(TSe2)n, with M = Pb, Bi Ce} and T = W, Nb, Ta} self assemble from designed precursors. The values of m and n represent, respectively, the number of MSe and TSe2 structural units of the unit cell

Effect of Tin Doping on alpha-Fe2O3 Photoanodes for Water Splitting

June 28, 2012
Author(s)
Christopher C. Bohn, Amit Agrawal, Erich C. Walter, Mark D. Vaudin, Andrew Herzing, Paul M. Haney, Albert A. Talin, Veronika Szalai
Sputtered-deposited films of α-Fe2O3 of thickness 600 nm were investigated as photoanodes for solar water splitting and found to have photocurrents as high as 0.8 mA/cm2 at 1.23 V vs. the reversible hydrogen electrode (RHE). The incorporation of Sn into

Preparation and Measurement Methods for Studying Nanoparticle Aggregate Surface Chemistry

June 8, 2012
Author(s)
Christopher W. Szakal, James McCarthy, Andrew R. Konicek, Kacie Louis, Benjamin Yezer, Andrew A. Herzing, Robert Hamers, Richard D. Holbrook
Despite best efforts at controlling nanoparticle (NP) surface chemistries, the environment surrounding nanomaterials is always changing and can impart a permanent chemical memory. We present a set of preparation and measurement methods to be used as the

Nanoscale structure measurements for polymer-fullerene photovoltaics

February 3, 2012
Author(s)
Dean M. DeLongchamp, Regis J. Kline, Andrew A. Herzing
This review covers methods to measure key aspects of nanoscale structure in organic photovoltaic devices based on polymer-fullerene bulk heterojunctions. The importance of nanoscale structure to the power conversion efficiency and stability of these

Molecular Order in High-Efficiency Polymer/Fullerene Bulk Heterojunction Solar Cells

September 22, 2011
Author(s)
Matthew R. Hammond, Regis J. Kline, Andrew A. Herzing, Lee J. Richter, David Germack, Hyun W. Ro, Christopher L. Soles, Daniel A. Fischer, Tao Xu, Luping Yu, Michael F. Toney, Dean M. DeLongchamp
We report quantitative measurements of ordering, molecular orientation, and nanoscale morphology in the active layer of bulk heterojunction organic photovoltaic cells based on a thieno[3,4-b]thiophene-alt-benzodithiophene copolymer (PTB7), which has been

Selective Oxidation of Glycerol by Highly Active Bimetallic Catalysts at Ambient Temperature under Base Free Conditions

August 24, 2011
Author(s)
Andrew A. Herzing, Gemma L. Brett, Peter Miedziak, Nikolaos Dimitratos, Meenakshisundaram Sankar, Marco Conte, Jose A. Lopez-Sanchez, David W. Knight, Stuart H. Taylor, Graham J. Hutchings, Qian He, Christopher J. Kiely
AuPt or AuPd nanoparticles when supported on Mg(OH)2 are highly active for the selective oxidation of glycerol under base-free conditions at ambient temperatures. When bimetallic particles with the appropriate composition are prepared, catalysts with a

Flexible Memristors Fabricated through Sol-Gel Hydrolysis

May 1, 2011
Author(s)
Joseph L. Tedesco, Nadine Gergel-Hackett, Laurie Stephey, Andrew A. Herzing, Madelaine H. Hernandez, Joseph J. Kopanski, Christina A. Hacker, Curt A. Richter
Memristors were fabricated on flexible polyethylene terephthalate substrates consisting of an oxide film generated through hydrolysis of a spun-on sol-gel. X-ray photoelectron spectroscopy, spectroscopic ellipsometry, transmission electron microscopy, and

Conduction and Loss Mechanisms in Flexible Oxide-Based Memristors

March 21, 2011
Author(s)
Joseph L. Tedesco, Nadine Gergel-Hackett, Laurie Stephey, Andrew A. Herzing, Madelaine H. Hernandez, Christina A. Hacker, Jan Obrzut, Lee J. Richter, Curt A. Richter
In order to study the conduction and loss mechanisms behind their operation, flexible sol-gel based memristors were fabricated with differing oxide film thicknesses and device sizes. XPS, TEM, EELS, and VASE measurements indicated the oxide was amorphous

Electron Vortex Beams with High Quanta of Orbital Angular Momentum

January 14, 2011
Author(s)
Benjamin James McMorran, Amit K. Agrawal, Ian M. Anderson, Andrew A. Herzing, Henri J. Lezec, Jabez J. McClelland, John Unguris
Analogous to vortices in light optical beams, electron optical beams with helical wavefronts carry orbital angular momentum and promise new capabilities for electron microscopy and other applications. We use nanofabricated diffraction holograms in an