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Search Publications by: Lee J Richter (Fed)

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Displaying 1 - 25 of 150

Salts as additives: A route to improve performance and stability of n-type organic electrochemical transistors

March 9, 2023
David Ohayon, Lucas Flagg, Andrea Giugni, Shofarul Wustoni, Ruipeng Li, Tania Hidalgo, Abdul Hamid Emwas, Rajendar Sheelamanthula, Iain McCulloch, Lee J. Richter, Sahika Inal
Organic electrochemical transistors (OECTs) are becoming increasingly ubiquitous in a wide variety of applications at the interface with biological systems, including biosensing, neuromorphic computing, and logic circuits. The widespread use of these

Certification of Standard Reference Material(R) 2196 Axial Resolution Standard for Optical Medical Imaging

February 7, 2023
Jeeseong C. Hwang, Kimberly Briggman, Nikki Rentz, Hyun-Jin Kim, David W. Allen, Lee J. Richter, Sowon Yoon, John Lu
Medical imaging devices and systems must be calibrated to ensure uniformity and reliability of test results. A standard reference material (SRM) or "phantom", as it is known in the medical imaging community, is used to replicate fundamental characteristics

Hydration of a side-chain-free n-type ladder semiconducting polymer driven by electrochemical doping

January 11, 2023
Jiajie Guo, Lucas Flagg, Duyen Tran, Shinya Chen, Ruipeng Li, Nagesh Kolhe, Rajiv Giridharagopal, Samson A. Jenekhe, Lee J. Richter, David Ginger
We study the organic electrochemical transistor (OECTs) performance of the ladder polymer, poly(benzimidazobenzophenanthroline) (BBL) in an attempt to better understand how an apparently insoluble side-chain free polymer is able to operate as an OECT with

All-Printed Ultrahigh-Responsivity MoS2 Nanosheet Photodetectors Enabled by Megasonic Exfoliation

July 5, 2022
Lee J. Richter, Lidia Kuo, Vinod Sangwan, Sonal Rangnekar, Ting-Ching Chu, David Lam, Shehao Zhu, Ruipeng Li, Julia Downing, Benjamin Luijten, Lincoln Lauhon, Mark Hersam
Printed two-dimensional materials, derived from solution-processed inks, offer scalable and cost-effective routes to mechanically flexible optoelectronics. With micron-scale control and broad processing latitude, aerosol-jet printing (AJP) is of particular

Fast Near-Infrared Photodetection using III-V Colloidal Quantum Dots

June 29, 2022
Lee J. Richter, Bin Sun, Amin M. Najarian, Chao Zheng, Laxmi K. Sagar, Min-Jae Choi, Xiyan Li, Larissa Levina, Se-Woong Baek, Seungjin Lee, Ahmad R. Kirmani, Jehad Abed, Mengxia Liu, Peicheng Li, Oleksandr Voznyy, Zheng H. Lu, F. Pelayo G. de Arquer, Edward H. Sargent
Colloidal quantum dots (CQDs) are promising materials for IR light detection due to their tunable bandgap and their solution processing; however, to date, the time response of CQD IR photodiodes has been inferior to that provided by Si and InGaAs. We

In-situ studies of the swelling by electrolyte in the electrochemical doping of an ethylene glycol substituted polythiophene

June 13, 2022
Lee J. Richter, Lucas Flagg, Lauren Asselta, Nicholas D'Antona, Natalie Stingelin, Tommaso Nicolini, Jonathan Onorato, Christine Luscombe, Ruipeng Li
Organic mixed ionic electronic conductors (OMIECs) have the potential to enable diverse new technologies, ranging from biosensors to flexible energy storage devices and neuromorphic computing platforms. However, study of these materials in their operating

Impact of Varying Side Chain Structure on Organic Electrochemical Transistor Performance: A Series of Oligoethylene Glycol-substituted Polythiophenes

April 19, 2022
Shinya Chen, Lucas Flagg, Jonathan Onorato, Lee J. Richter, Christine Luscombe, David Ginger
We study the electrochemical doping/dedoping kinetics, and the organic electrochemical transistor (OECT) performance of a series polythiophene homopolymers with ethylene glycol units in their side chains using both kosmotropic and chaotropic anion

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

Side Chain Engineering Control of Mixed Conduction in Oligoethylene Glycol-Substituted Polythiophenes

August 31, 2021
Jonathan Onorato, Zhongyang Wang, Yangyang Sun, Christian Nowak, Ban Dong, Lucas Flagg, Ruipeng Li, Lee J. Richter, Fernando Escobedo, Paul Nealey, Shrayesh Patel, Christine Luscombe
A major limitation for polymeric mixed ionic/electronic conductors (MIECs) is the trade-off between ionic and electronic conductivity; changes made that improve one typically hinder the other. In order to address this fundamental problem, this work

Polarized X-ray scattering measures molecular orientation in polymer-grafted nanoparticles

August 12, 2021
Subhrangsu Mukherjee, Dean DeLongchamp, Eliot Gann, Daniel Sunday, Lee J. Richter, Jason Streit, Richard A. Vaia, Baskar Ganapathysubramanian, Kumar Saurabh, Adarsh Krishnamurthy
Polymer chains are attached to nanoparticle surfaces for many purposes, including altering solubility, influencing aggregation, dispersion, and even tailoring immune responses in drug delivery. The most unique structural motif of polymer-grafted

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)

Confinement and Processing Can Alter the Morphology and Periodicity of Bottlebrush Block Copolymers in Thin Films

December 22, 2020
Daniel Sunday, Moshe Dolejsi, Alice B. Chang, Lee J. Richter, Ruipeng Li, Paul Nealey, Robert H. Grubbs
Bottlebrush block copolymers (BBCPs) are intriguing architectural variations on linear BCPs with highly tunable structure. Confinement can have a significant impact on polymer assembly, giving rise to changes in morphology, assembly kinetics, and properties

A low-swelling, polymeric mixed conductor operating in aqueous electrolytes

November 30, 2020
Lee J. Richter, Tommaso Nicolini, Jokubas Surgailis, Achileas Savva, Guillaume Wantz, Olivier Dautel, Georges Hadiziioannou, Natalie Stingelin
Organic mixed conductors find use in batteries, bioelectronics technologies, neuromorphic computing and sensing. While great progress has been achieved, polymer-based mixed conductors frequently experience significant volumetric changes during ion uptake

Towards fast screening of organic solar cell blends

August 5, 2020
Lee J. Richter, Artem Levistsky, Giovanni M. Matrone, Aditi Khirbat, Ilaria Bargigia, Xiaolei Chu, Oded Nahor, Tamar Segal-Perez, Adam Moule, Carlos Silva, Natalie Stingelin, Gitti L. Frey
The ever increasing library of materials systems developed for organic solar-cells, including highly promising non-fullerene acceptors and new, high-efficiency donor polymers, demands the development of methodologies that (i) allow fast screening of a

Efficient electrically-powered CO2-to-ethanol via suppression of deoxygenation

May 11, 2020
Xue Wang, Wang Ziyun, F. P. Garcia de Arquer, Cao-Thang Dinh, Adnan Ozden, Yuguang C. Li, Dae-Hyun Nam, Jun Li, Yi-Sheng Liu, Joshua Wicks, Zitao Chen, Miaofang Chi, Bin Chen, Ying Wang, Jason Tam, Jane Y. Howe, Andrew Proppe, Peter Todrovic, Fengwang Li, Tao-Tao Zhuang, Christine M. Garbardo, Ahmad R. Kirmani, Christopher McCallum, Yanwei Lum, Mingchuan Luo, Yimeng Min, Aoni Xu, Colin P. O'Brien, Bello Stephen, Bin Sun, Alexander H. Ip, Lee J. Richter, Shana O. Kelley, David Sinton, Edward H. Sargent
The carbon dioxide electroreduction reaction (CO2RR) provides avenues to the production renewable ethanol, a high-energy-density fuel. Unfortunately, until now, the ethanol Faradaic efficiency (FE) has lain below 27% in CO2RR studies reported at total

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