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Search Publications by: Lee J Richter (Assoc)

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Displaying 51 - 75 of 155

Real-time Photoluminescence Studies of Thin Film Formation in Organic Solar Cells

February 29, 2016
Author(s)
Sebastian Engmann, Felicia A. Bokel, Hyun W. Ro, Dean M. DeLongchamp, Lee J. Richter
We present a method to study the structural evolution of organic bulk-heterojunctions via real-time, in-situ, steady state photoluminescence (PL). In-situ PL, in combination with real-time transmission and reflection measurements, allowed us to

The Structural Origin of Electron Injection Enhancements with Fulleropyrrolidine Interlayers

February 25, 2016
Author(s)
Lee J. Richter, Hyunbok Lee, Christopher McNeil, Eliot Gann, Lars Thomsen, S. Park, J. Jeong, Z. A. Page, Egle Puodziukynaite, Todd Emrick, Alejandro Briseno, John C. Stephenson, Dean M. DeLongchamp
Market demand for ubiquitous, increased functionality products at low cost (the internet of things) is spurring development in additive, solution processing of electronic devices. Performance in thin-film functional devices, be they transistors, diodes, or

Classification of Semiconducting Polymeric Mesophases to Optimize Device Post-Processing

August 17, 2015
Author(s)
Chad R. Snyder, Regis J. Kline, Dean M. DeLongchamp, Ryan C. Nieuwendaal, Lee J. Richter, Martin Heeney, Iain McCulloch
Semiconducting polymers form a variety of phases and mesophases that respond differently to post-deposition solvent or thermal treatments. Here it is shown that classification of these materials into their appropriate mesophases can be a useful tool to

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

Direct correlation of charge transfer absorption with molecular donor:acceptor interfacial area via photothermal deflection spectroscopy

April 9, 2015
Author(s)
Lee J. Richter, Dean M. DeLongchamp, Natalie Stingelin, Alberto Salleo, Martin Heeney, Aram Amassian, John deMello, James Bannock, Fiona H. Scholes, Scott Watkins, Zhuping Fei, Koen Vandewal
ABSTRACT: Here, we show that the Charge Transfer (CT) absorption signal in bulk (BHJ) solar cell blends, measured by photothermal deflection spectroscopy (PDS), is directly proportional to the density of molecular donor/acceptor interfaces. Since the

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

In-situ morphology studies of the mechanism for solution additive effects on the formation of bulk heterojunction films.

September 29, 2014
Author(s)
Lee J. Richter, Dean M. DeLongchamp, Kang W. Chou, Aram Amassian, A Hexemer, Eric Schaible, Felicia A. Bokel, Sebastian Engmann
The most successful active film morphology in organic photovoltaics is the bulk heterojunction (BHJ). The performance of a BHJ arises from a complex interplay of the spatial organization of the segregated donor and acceptor phases and the local order

Attachment of a Reduction-Oxidative Active Diruthenium Compound to Au and Si Surfaces by Click Chemistry

August 10, 2014
Author(s)
Sujitra J. Pookpanratana, Joseph W. Robertson, Curt A. Richter, Christina A. Hacker, Lee J. Richter, Julia Savchenko, Steven Cummings, Tong Ren
We report the formation of molecular monolayers containing redox-active diruthenium(II,III) compound to gold and silicon surfaces via “click” chemistry. The use of Cu-catalyzed azide-alkyne cycloaddition enables modular design of molecular surfaces and

Morphological origin of charge transport anisotropy in aligned polythiophene thin films

June 11, 2014
Author(s)
Brendan T. O'Connor, Obadiah G. Reid, Xinran Zhang, Regis Kline, Lee Richter, David Gundlach, Dean DeLongchamp, Michael F. Toney, Nikos Kopidakis, Garry Rumbles
The morphological origin of anisotropic charge transport in uniaxially strain aligned poly(3-hexylthiophene) (P3HT) films is investigated. The macroscale field effect mobility anisotropy is measured in an organic thin film transistor (OTFT) configuration

Nonlinear Vibrational Spectrometry

December 31, 2013
Author(s)
Lee Richter
Second order nonlinear spectroscopies such as sum frequency generation (SFG) are intrinsically interface sensitive and enable sub monolayer sensitivity to be achieved at buried, optically accessible interfaces. Vibrationally-resonant SFG allows bond

Vertically Segregated Structure and Properties of small molecule-polymer blend semiconductors for organic thin film transistors

August 27, 2012
Author(s)
Nayool Shin, Dean DeLongchamp, Jihoon Kang, Regis J. Kline, Lee J. Richter, Vivek Prabhu, Balaji Purushothamanc, John E. Anthony, Do Y. Yoon
The phase-segregated structure and the electrical properties of thin film blends of the small-molecule semiconductor fluorinated 5,11-bis(triethylsilylethynyl) anthradithiophene with insulating binder polymers were studied for organic thin film transistor

3-Aminopropyltriethoxysilane Functionalization and Biotinylation of 4H-SiC for Immobilization of Streptavidin

June 1, 2012
Author(s)
Elissa H. Williams, Albert Davydov, John A. Schreifels, Mulpuri V. Rao, Abhishek Motayed, Siddarth Sundaresan, Peter Bocchini, Lee J. Richter, Gheorghe Stan, Kristen L. Steffens, Rebecca A. Zangmeister
(0001) 4H-SiC was functionalized with 3-aminopropyltriethoxysilane (APTES) and subsequently biotinylated for the immobilization of streptavidin. Atomic force microscopy (AFM), x-ray photoelectron spectroscopy (XPS), ellipsometry, fluorescence microscopy

Surface Plasmon Polariton Raman Microscopy

January 1, 2012
Author(s)
Hae-Wook Yoo, Lee J. Richter, Hee-Tae Jung, Chris A. Michaels
We report surface plasmon polariton (SPP) mediated Raman microscopy on dielectric films in contact with a Ag layer at 785 nm with spatial resolution approaching the optical diffraction limit and reasonable spectral acquisition times. The excitation and

A synchrotron beamline for extreme-ultraviolet photoresist testing

September 30, 2011
Author(s)
Charles S. Tarrio, Steven E. Grantham, Shannon B. Hill, Nadir S. Faradzhev, Lee J. Richter, Chester Knurek, Thomas B. Lucatorto
Before being used in an extreme-ultraviolet (EUV) scanner, photoresists must first be evaluated for sensitivity and tested to ensure that they will not contaminate the scanner optics. The new NIST facility described here provides data on the contamination

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

The NIST EUV facility for advanced photoresist qualification using the witness-sample test

August 29, 2011
Author(s)
Steven E. Grantham, Charles S. Tarrio, Shannon B. Hill, Lee J. Richter, J. van Dijk, C. Kaya, N. Harned, R. Hoefnagels, M. Silova, J. Steinhoff
Before being used in an extreme-ultraviolet (EUV) scanner, photoresists must first be qualified to ensure that they will not excessively contaminate the scanner optics or other parts of the vacuum environment of the scanner. At the National Institute of

Optics contamination studies in support of high-throughput EUV lithography tools

March 25, 2011
Author(s)
Shannon B. Hill, Fardina Asikin, Lee J. Richter, Steven E. Grantham, Charles S. Tarrio, Thomas B. Lucatorto, Sergiy Yulin, Mark Schurmann, Viatcheslav Nesterenko, Torsten Feigl
We report on optics contamination rates induced by exposure to broad-bandwidth, high-intensity EUV radiation peaked near 8 nm in a new beamline at the NIST synchrotron. The peak intensity of 50 mW/mm2 allows extension of previous investigations of

Conduction and Loss Mechanisms in Flexible Oxide-Based Memristors

March 21, 2011
Author(s)
Joseph L. Tedesco, Nadine Gergel-Hackett, Laurie Stephey, Andrew Herzing, Madelaine H. Hernandez, Christina Hacker, Jan Obrzut, Lee Richter, Curt 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

Controlling the Microstructure of Solution-Processible Small Molecules in Thin-Film Transistors through Substrate Chemistry

February 4, 2011
Author(s)
Regis J. Kline, Steven D. Hudson, Xinran Zhang, David J. Gundlach, Andrew Moad, Lee J. Richter, Oana Jurchescu, Thomas Jackson, Sanker Subramanian, John E. Anthony, Michael F. Toney
Solution-processible small molecules have tremendous potential for providing both high charge carrier mobility and low cost processing. This study outlines a detailed microstructural study of the effect of substrate chemistry on fluorinated 5,11-bis

Influence of substrate on crystallization in polythiophene/fullerene blends

January 13, 2011
Author(s)
Lee J. Richter, Christine He, David Germack, R Joseph Kline, Dean DeLongchamp, Daniel A. Fischer, Chad R. Snyder, James G. Kushmerick
The nanoscale morphology of the active layer in organic, bulk heterojunction (BHJ) solar cells is crucial to device performance. Often a combination of casting conditions and post deposition thermal treatment are used to optimize the morphology. In general
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