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Search Publications by

Lee J Richter (Fed)

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Displaying 1 - 25 of 132

Enhanced Near-Field Raman Spectroscopy

October 12, 2021
C E. Dentinger, Stephan J. Stranick, Lee J. Richter, Richard R. Cavanagh
Near-field Raman spectroscopy can be used to obtain chemical specificity with the subwavelength spatial resolution of near-field scanning optical microscopy (NSOM). We report detailed measurements of near-field Raman spectra from a single crystal diamond

The role of orientation in the MEL response of OLEDs

July 13, 2021
Sebastian Engmann, Emily Bittle, Lee J. Richter, Rawad Hallani, John Anthony, David J. Gundlach
Magneto electroluminescence (MEL) is emerging as a powerful tool for the study of spin dynamics in emitting devices. The shape of the MEL response is typically used to draw qualitative inference on the dominant process (singlet fission or triplet fusion)

Chemically Orthogonal Hole Transport Layer for Efficient Colloidal Quantum Dot Solar Cells

March 20, 2020
Margherita Biondi, Min-Jae Choi, Olivier Ouellette, Se-Woong Baek, Petar Todorovi?, Bin Sun, Peicheng Li, Ahmad R. Kirmani, Laxmi Chiluka, Lee J. Richter, Sjoerd Hoogland, Zheng-Hong Lu, F. Pelayo Garc?a de Arquer, Edward H. Sargent, Mingyang Wei
Colloidal quantum dots (CQDs) are of interest in light of their solution-processing and bandgap tuning. Advances in the performance of CQD optoelectronic devices require fine control over the properties of each layer in the device materials stack. This is

Polarization Dependence of Charge Conduction in Conjugated Polymer Films Investigated with Time- Resolved Terahertz Spectroscopy

March 6, 2020
Timothy J. Magnanelli, Sebastian Engmann, Jared K. Wahlstrand, John C. Stephenson, Lee J. Richter, Edwin J. Heilweil
We interrogate polarization anisotropy associated with charge conduction in films of the block co polymer PCDTPT, consisting of alternating cyclopenta dithiophene (donor) and thiadiazolo pyridine (acceptor) units with respect to sample morphology. Film

Sub-picosecond charge-transfer at near-zero driving force in polymer:non-fullerene acceptor blends and bilayers

February 11, 2020
Yufei Zhong, Martina Causa, Gareth J. Moore, Philipp Krauspe, Bo Xiao, Jonas Kublitski, Rishi Shivhare, Johannes Benduhn, Eyal BarOr, Subhrangsu Mukherjee, Kaila Yallum, Julien R?hault, Stefan C. Mannsfeld, Dieter Neher, Lee J. Richter, Dean DeLongchamp, Frank Ortmann, Koen Vandewal, Erjun Zhou, Banerji Natalie, Florian Gunther
Organic photovoltaics based on non-fullerene acceptors (NFAs) show record efficiency of 16 to 17% and increased photovoltage owing to the low driving force for interfacial charge-transfer. However, the low driving force potentially slows down charge

Dynamical evolution of the 2D/3D interface: a hidden driver behind perovskite solar cell instability

January 3, 2020
Lee J. Richter, Ahmad R. Kirmani, Albertus A. Sutano, Nikita Drigo, Ines G. Benito, Valentine I. Queloz, Kyung T. Cho, Pascal A. Schouwink, Mohammad K. Nazeeruddin, Giulia Grancini, Sanghyun Paek
Engineering two-/three-dimensional (2D/3D) perovskite solar cells is nowadays a popular strategy for efficient and stable devices. However, the exact function of the 2D/3D interface in controlling the long-term device behavior is still obscure. Here, we

CO2 electrolysis to multicarbon products at activities greater than 1 A cm(-2)

December 23, 2019
Lee J. Richter, Ahmad R. Kirmani, F. P. Garcia de Arquer, Cao-Thang Dinh, Adnan Ozden, Joshua Wicks, Christopher McCallum, Gabardo M. Christine, Ali Seifitokaldani, Xue Wang, Yuguang C. Li, Fengwang Li, Jonathan Edwards, Steven J. Thorpe, David Sinton, Edward H. Sargent, Nam Dae-Hyun, Dae-Hyun Nam
Electrolysis offers an attractive route to upgrade greenhouse gases such as carbon dioxide (CO2) to valuable fuels and feedstocks; however, productivity is often limited by gas diffusion through a liquid electrolyte to the surface of the catalyst. Here, we

Efficient upgrading of CO to C3 fuel using asymmetric C-C coupling active sites

November 29, 2019
Lee J. Richter, Ahmad R. Kirmani, Xue Wang, Wang Ziyuan, Dinh Cao-Thang, Li Jun, Nam Dae-Hyun, Li Fengwang, Huang Chun-Wei, Tan Chih-Shan, Chen Zitao, Chi Miaofang, Gabardo M. Christine, Seiifitokaldani Ali, Todorovic Petar, Proppe Andrew, Pang Yuanjie, wang yuhang, Ip H. Alexander, Shen-Chuan Lo, shana O. kelley, David Sinton, Edward H. Sargent, Tao-Tao Zhuang, Benjamin Scheffel
The electroreduction of C1 feedgas to high-energy-density fuels provides an attractive avenue to the storage of renewable electricity. Much progress has been made to improve selectivity to C1 and C2 products, however, the selectivity to desirable high

Crystal Orientation Drives the Interface Physics at 2/3-Dimensional Hybrid Perovskites

September 9, 2019
Lee J. Richter, Ahmad R. Kirmani, Marine E. Bouduban, Valentine I. Queloz, Valentina M. Caselli, Kyung T. Cho, Sanghyun Paek, Cristina Roldan-Carmona, Jacques E. Moser, Tom J. Savenije, Mohammad K. Nazeeruddin, Giulia Grancini
Combining halide perovskites with tailored dimensionality into two/three-dimensional (2D/3D) systems has revealed a powerful strategy to boost the performances of perovskite photovoltaics (PVs). Despite recent advances, a clear understanding of the

Morphology of a thermally stable small molecule OPV blend comprising a liquid crystalline donor and fullerene acceptor

June 4, 2019
Alexander J. Bourque, Sebastian Engmann, Allison Fuster, Chad R. Snyder, Lee J. Richter, Paul B. Geraghty, David J. Jones
Recently organic photovoltaic (OPV) devices comprising the small molecule liquid-crystalline donor, benzodithiophene-quaterthiophene-rhodanine (BQR), were demonstrated to achieve high performance when thermally processed, avoiding the need for slow-drying

Stable Postfullerene Solar Cells via Direct C-H Arylation Polymerization. Morphology-Performance Relationships

May 16, 2019
Subhrangsu Mukherjee, Thomas Aldrich, Weigang Zhu, Lee J. Richter, Eliot Gann, Dean DeLongchamp, Antonio Facchetti, Ferdinand Melkonyan, Tobin Marks
The scope of the environmentally benign direct C-H arylation polymerization (DARP) process is validated and significantly extended in the synthesis of a high-performance benzodithiophene- based copolymer series, PBDT(Ar)-FTTE, with previously untested and

In Situ Back-Contact Passivation Improves Photovoltage and Fill Factor in Perovskite Solar Cells

February 10, 2019
Lee J. Richter, Ahmad R. Kirmani, Furui Tan, Hairen Tan, Wei Mingyang, Makhsud I. Saidaminov, Mengxia Liu, Mei Anyi, Peicheng Li, Chih-Shan Tan, Xiwen Gong, Yongbiao Zhao, Ziru Huang, James Z. Fan, Rafael Quintero-Bermudez, Kim Junghwan, Yicheng Zhao, Oleksandr Voznyy, Zheng-Hong Lu, Weifeng Zhang, Edward H. Sargent, Bowen Zhang, Yueye Gao, Feng Zhang
Organic–inorganic hybrid perovskite solar cells (PSCs) have seen a rapid rise in power conversion efficiencies in recent years; however, they still suffer from interfacial recombination and charge extraction losses at interfaces between the perovskite

Higher Order Effects in Organic LEDs with Sub-bandgap Turn-on

January 16, 2019
Sebastian Engmann, Adam J. Barito, Emily Bittle, Chris Giebink, Lee J. Richter, David J. Gundlach
Spin-dependent nonlinear processes in organic materials such as singlet-fission and triplet- triplet annihilation could increase the performance for photovoltaics, detectors, and light emitting diodes. Rubrene/C60 light emitting diodes exhibit a distinct

A simple and robust approach to reducing contact resistance in organic devices

December 3, 2018
Lamport Zachary, Katrina Barth, Hyunsu Lee, Martin Guthold, Iain McCulloch, John E. Anthony, Lee J. Richter, Eliot Gann, Dean DeLongchamp, Oana Jurchescu
Efficient injection of charge carriers from the contacts into the semiconductor layer is crucial for achieving high-performance organic devices. The potential drop necessary to accomplish this process yields a resistance associated with the contacts

SEIRAS Study of Chloride Mediated Polyether Adsorption on Cu

August 31, 2018
Thomas P. Moffat, Daniel Josell, Lee J. Richter
Surface enhanced infrared absorption spectroscopy (SEIRAS) was used to examine the co- adsorption of a selection of polyethers with Cl- under conditions relevant to superconformal Cu electrodeposition in CuSO4-H2SO4 electrolytes. In 0.1 mol/L H2SO4 a

Characterization of Interfacial Structure in Polymer-Fullerene Bulk Heterojunctions via 13C {2H} Rotational Echo Double Resonance NMR

July 13, 2018
Ryan C. Nieuwendaal, Dean M. DeLongchamp, Martin Heeney, Jan Hummelen, Chad R. Snyder, Ronald L. Jones, Sebastian Engmann, Lee J. Richter, Zhuping Fei, Alex Sieval
We introduce a new application of solid state NMR measurements towards characterizing the donor-acceptor interfaces within bulk heterojunction (BHJ) films. Rotational echo double resonance (REDOR) is used to measure dipolar couplings between 13C nuclei on

Blade Coating Aligned, High-Performance, Semiconducting-Polymer Transistors

February 22, 2018
Lee J. Richter, Hyun W. Ro, Regis J. Kline, Daniel A. Fischer, Dean M. DeLongchamp, Lars Thomsen, Christopher McNeil, Dawei Wu, Maria Kaplan, Eliot H. Gann
Recent demonstration of mobilities in excess of 10 cm2V-1s-1 have energized research in solution deposition of polymers for thin film transistor applications. Due to the lamella motif of most soluble, semiconducting polymers, the local mobility is

Simple Transfer from Spin Coating to Blade Coating Through Processing Aggregated Solutions

September 22, 2017
Jeff L. Hernandez, Nabankur Deb, Rylan M. Wolfe, Chi K. Lo, Sebastian Engmann, Lee J. Richter, John R. Reynolds
To develop an understanding of the effect spin coating or blade coating have on the morphology of polymer:fullerene thin films for organic solar cells, we have investigated the morphology of poly[5-(2-hexyldecyl)-1,3-thieno[3,4-c]pyrrole-4,6-dione-alt-5,5-

Morphological characterization of fullerene and fullerene-free organic photovoltaics by combined real and reciprocal space techniques

May 26, 2017
Donglin Zhao, Qinghe Wu, Luping Yu, Harald Ade, Dean DeLongchamp, Lee J. Richter, Subhrangsu Mukherjee, Andrew Herzing
Morphology can play a critical role in determining function in organic photovoltaic (OPV) systems. Recently molecular acceptors have showed promise to replace¬ fullerene derivatives as acceptor materials in bulk heterojunction solar cells and have achieved

Reduced Bimolecular Recombination in Blade-Coated, High-Efficiency, Small-Molecule Solar Cells

March 22, 2017
Sebastian Engmann, Hyun W. Ro, Andrew A. Herzing, Dean M. DeLongchamp, Chad R. Snyder, Lee J. Richter, Adam J. Barito, David J. Gundlach
The full benefit of emerging solution deposited photovoltaic devices requires development of processes compatible with high speed manufacturing. Extensive studies of the lab-to-fab challenge have been performed on polymer donor based organic photovoltaics