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Search Publications by: Lucas Flagg (Fed)

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Displaying 1 - 20 of 20

Charge-state dependent ion condensation near conjugated polymer backbones

November 15, 2025
Author(s)
Dilara Meli, Quentin Thomas, Guillaume Freychet, Lucas Flagg, Iain McCulloch, David Beljonne, Lee Richter, Jonathan Rivnay
Despite the technological appeal of organic mixed ionic/electronic conductors (OMIECs) for a range of applications, a deep understanding of the fundamentals of mixed charge transport in these materials, especially regarding the ionic component, is lacking

Sterilizable Vertical n-Type Organic Electrochemical Transistors for Skin-conformal ECG Monitoring

May 6, 2025
Author(s)
Ji Hwan Kim, Inho Lee, Won-June Lee, Dongjoon Shin, Hyeongbeom Lee, Lucas Flagg, Jagrity Chaudhary, Liyan You, Keehoon Kang, Jianguo Mei, Sungjun Park
The development of stable, high-performance epidermal biosignal monitoring devices is critical for advancing wearable healthcare technologies. Here, we present a novel electrochemical transistor-based biosignal sensor utilizing a 4-terminal vertical

Controlling Doping Levels of n-PBDF Through Chemical Dedoping and Doping

April 15, 2025
Author(s)
Zhifan Ke, Lucas Flagg, Dean DeLongchamp, jianguo mei
Doping levels of conjugated polymers determine their conductivity, energetics, and optical properties. The recent discovery of highly conductive n-doped Poly (3,7-dihydrobenzo[1,2-b:4,5-b′]difuran-2,6-dione) (n-PBDF) has opened new possibilities for n-type

The Role of Side Chains and Hydration on Mixed Charge Transport in n-type Polymer Films

March 30, 2025
Author(s)
Lucas Flagg, Lee Richter, Jokubas Surgailis, Victor Druet, Sophie Griggs, Xiaocui Wu, Stefania Moro, David Ohayon, Christina Kousseff, Adam Marks, Iuliana Petruta Maria, Hu Chen, Maximilian Moser, Giovanni Costantini, Iain McCulloch, Sahika inal
Introducing polar ethylene glycol (EG) side chains to a conjugated polymer backbone is a well-established synthetic strategy to design organic mixed ion-electron conductors (OMIECs). However, the impact that film swelling has on mixed conduction properties

An easy to implement strategy for improving operational stability and controlling threshold voltage in organic electrochemical transistors: Combining chemical p-doping with degassed solvents

November 4, 2024
Author(s)
Vianna N. Le, Kyle N. Baustert, Megan Brown, Joel H. Bombile, Lucas Flagg, Karl Thorley, Alyssa Stubbers, Christina J. Kousseff, Olga Solomeshch, T. John Balk, Iain McCulloch, Nir Tessler, Chad Risko, Kenneth R. Graham, Alexandra F. Paterson
Although p-type organic mixed ionic electronic conductors (OMIECs) are susceptible to oxidation, it has not yet been considered as to whether oxygen, solvent degradation products, or degradation products formed in the solvent in the presence of oxygen

Correlation of Structure and Morphology in an Ethylene-glycol Side-chain Modified Polythiophene via Combined X-ray Scattering and Four-dimensional Scanning Transmission Electron Microscopy

October 10, 2024
Author(s)
Andrew Herzing, Lucas Flagg, Chad R. Snyder, Lee Richter, Jonathan Onorato, Christine Luscombe, Ruipeng Li
We report the results of a combined grazing incidence wide-angle X-ray scattering (GIWAXS) and four-dimensional scanning transmission microscopy (4D-STEM) analysis of the effects of thermal processing on poly(3[2-(2-methoxyethoxy)ethoxy]-methylthiophene- 2

New Method to Probe the Surface Properties of Polymer Thin Films by Two-Dimensional (2D) Inverse Gas Chromatography (iGC)

June 25, 2024
Author(s)
Whirang Cho, Lucas Flagg, Christopher Stafford, Jeremiah Woodcock, Daniel Burnett, Anett Kondor, Douglas Fox, John Hoffmann
Polymer-based functional surface coatings are extensively used in advanced technologies, including optics, energy, and environmental applications. Surface thermodynamic properties profoundly impact the molecular interactions that control interfacial

Trace Water Effects on Crystalline 1-Ethyl-3-methylimidazolium Acetate

May 16, 2023
Author(s)
Ashlee Aiello, John Hoffman, Anthony Kotula, Lucas Flagg, Ruipeng Li, Jeremiah Woodcock
Spontaneous room temperature crystallization of 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]) was observed upon removal of trace water. To ensure that this observation was not produced by trace water or other contaminants, sample purity was confirmed

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

March 9, 2023
Author(s)
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

Quantitative relationships between film morphology, charge carrier dynamics, and photovoltaic performance in bulk-heterojunction binary vs. ternary acceptor blends

February 7, 2023
Author(s)
Weigang Zhu, Guoping Li, Subhrangsu Mukherjee, Natalia Powers-Riggs, Leighton Jones, Eliot Gann, R Joseph Kline, Andrew Herzing, Jenna Logsdon, Lucas Flagg, Charlotte Stern, Ryan Young, Kevin Kohlstedt, George Schatz, Dean DeLongchamp, Michael Wasielewski, Ferdinand Melkonyan, Antonio Facchetti, Tobin Marks
Addressing pertinent and perplexing questions regarding why nonfullerene acceptors (NFAs) promote higher power conversion efficiencies (PCEs) than traditional fullerenes and how photoactive bulk heterojunction (BHJ) film morphology, charge photogeneration

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

January 11, 2023
Author(s)
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

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

June 13, 2022
Author(s)
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
Author(s)
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

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

August 31, 2021
Author(s)
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
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