Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session X34: Organic Electronics III: Electrochemical Transistors and Doping |
Hide Abstracts |
Sponsoring Units: DPOLY Chair: Dean DeLongchamp, National Institute of Standards and Technology Room: 506 |
Friday, March 6, 2020 11:15AM - 11:27AM |
X34.00001: Charge and Ion Transport in Radical Polymer-based Organic Electrochemical Transistors Bryan Boudouris, Ho Joong Kim Radical polymers are composed of a non-conjugated macromolecular backbone with open-shell sites that are present on the side chains of each repeat unit. Previously, we have demonstrated that this macromolecular design motif alters the route by which charge is transported in solid-state electronic devices when compared with the more common conjugated polymers utilized in organic electronics. Here, we report on the application of a specific high-performance radical polymer, poly(4-glycidyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl) (PTEO), as the active layer component in an electrolyte-gated organic electrochemical transistor (OECT) device structure. Specifically, we establish the differences in charge and ion transport (i.e., mixed conduction) in these inherently glassy radical polymer systems relative to many oft-used OECT semicrystalline macromolecular materials. Moreover, we highlight the unique synergies that exist between mixed conduction that exist in non-conjugated radical polymer systems. Finally, we manipulate the degree of crosslinking within the radical polymer thin films after casting of the film (i.e., through the use of photoinitiated crosslinking) in order to demonstrate a mechanically-stable, solvent-robust OECT that achieves high device performance as well. |
Friday, March 6, 2020 11:27AM - 11:39AM |
X34.00002: Quantifying the Energetics of Ion Injection into Mixed Ionic/Electronic Conductors Lucas Flagg, Connor Bischak, Ramsess Javier, David S Ginger Organic electrochemical transistors (OECTs) rely on the electrochemical doping of an organic semiconductor to modulate the conductivity of the channel. This doping process requires electronic charge injection into the polymer from the metal contacts, as well as charge compensation by an ion provided by the electrolyte. Numerous factors have been shown to affect the ease and speed of ion injection including polymer side chain, polymer crystallinity, ion type, pH, solvent, etc. Here we use kinetics derived from temperature dependent spectroelectrochemistry measurements to extract the activation energy of ion injection into a polymer semiconductor. We compare the energetics of injection in a variety of different polymers, salts, and solvents to quantify the contribution of each of the factors controlling ion injection. A deeper understanding of the relative importance of each factor will help with future design of mixed ionic/electronic conductors. |
Friday, March 6, 2020 11:39AM - 11:51AM |
X34.00003: Counter-ion exchange as a tool to modulate polaron delocalization and temperature stability of doped polymeric semiconductors Elayne Thomas, Kelly A Peterson, Dakota Rawlings, Rachel A Segalman, Michael L. Chabinyc The design of high-performance doped semiconductors requires an understanding of the coupling between ionic and electronic carriers. We utilize a method of counter-ion exchange using the polymeric semiconductor PBTTT-C14 to deconvolute the effects of ionic/polaronic interactions with the electrical properties of doped semiconducting polymers. Here, the dopant NOPF6 is used followed by the exchange of counter-ions ranging from 5 to 11 Å in diameter. The long-range order of the polymeric crystallites is not affected with this exchange process while effectively modifying the counter-ion distance to the charge carrier. Doped films achieve electrical conductivity of 320 S/cm and is not sensitive to an increased ion-polaron distance. We posit that other factors dominate the electrical properties at a device scale, such as the morphology and presence of domain boundaries. Interestingly, the temperature stability of the doped film can be drastically improved with the use of counter-ions containing less labile bonds. This platform serves as a unique way to retain the morphology of polymeric thin films while studying charge interactions at the local scale. |
Friday, March 6, 2020 11:51AM - 12:03PM |
X34.00004: The role of counter ion structure on the spatial distribution and molecular configuration of charge carriers in solid state electrochemically doped conjugated polymers Dakota Rawlings, Rachel A Segalman, Michael L. Chabinyc In a chemically doped or electrochemically doped conjugated polymer, electronic charge carriers are inherently associated with a countercharge in the form of a molecular or atomic counterion. It is expected that the structure of the counter ion will affect its distribution in the polymer film along with that of associated electronic charge carriers. Furthermore, the effect of counter ion structure on the charge storage configuration (i.e. polaron vs. bipolaron) is unknown. Here, we quantify the charge configuration and the distribution of charge carriers between aggregated and amorphous domains as a function of the counter ion structure in semicrystalline conjugated polymer films. We employ an organic electrochemical transistor with a cation tethered polymeric ionic liquid (PIL) as the gate dielectric, where the size and structure of the mobile anionic counterion in the PIL can be varied to modulate the counterion that is associated to charge carriers in the semiconductor. Operando electron paramagnetic resonance and in situ device measurements reveal the polaron to bipolaron ratio as a function of the gate bias for a range of counter ions. This is paired with in situ optical spectroscopy to determine the distribution of charge carriers between amorphous and aggregated domains. |
Friday, March 6, 2020 12:03PM - 12:15PM |
X34.00005: Understanding the Working Mechanism of Organic Electrochemical Transistors Vikash Kaphle, Pushpa Paudel, Bjorn Lussem The organic electrochemical transistor (OECT) is a key element for the field of organic bioelectronics [Nat. Rev. Mat. 3, 17086, 2018]. OECTs are versatile and can be functionalized for a wide range of analytes, including various metabolites, hormones, or neurotransmitters. |
Friday, March 6, 2020 12:15PM - 12:27PM |
X34.00006: Bio-Sensors Based on Organic Electrochemical Transistors Pushpa Paudel, Vikash Kaphle, Drona Dahal, Raj Kishen Radha Krishnan, Bjorn Lussem Organic Electrochemical Transistors (OECTs) are capable of sensing a wide variety of biomolecules such as Glutamate, Acetylcholine [1], Lactic acids [2], or Glucose [3]. However, despite this success, the precise sensing mechanisms is still under discussion. This lack of understanding precludes a targeted design of OECT applications and currently limits the sensitivity of these devices. Here, we study the working mechanism of OECT based neurotransmitter (Acetylcholine and Glutamate) and Glucose sensors. We discuss the selectivity of these sensors, and study the influence of channel dimensions on their sensitivity. Finally, approaches to increase the spatial and temporal resolution of these transistors are presented. |
Friday, March 6, 2020 12:27PM - 12:39PM |
X34.00007: A flexible complementary logic circuit built from two identical organic electrochemical transistors Lorenzo Travaglini, Adam P Micolich, Claudio Cazorla, Erica Zeglio, Antonio Lauto, Damia Mawad Organic electrochemical transistor (OECT) with a conjugated polymer as the electrically active channel is the basic unit in organic bioelectronic devices.1 Increased functionalities can be further achieved by building complementary logic circuits combining more than one OECT in different architectures. The simplest circuit can be built by connecting one p-type and one n-type organic semiconductors in series.2 In this study, we build a complementary logic circuit on a flexible substrate with two OECTs having one material as the active channel.3 We demonstrate its DC operation with a gain of ~ 7 and its AC response within a frequency range suitable for physiological applications. Our approach to use one single material as an active channel in both OECTs simplifies the manufacturing process and eliminates the need to source different materials with similar electrical performances. |
Friday, March 6, 2020 12:39PM - 12:51PM |
X34.00008: Humidity-Dependent Mixed Ionic-Electronic Conduction in Polythiophene-Derived Polyelectrolytes Garrett Grocke, Ban Dong, Shrayesh Patel Conjugated polyelectrolytes that can conduct both ionically and electronically are attractive candidates for next-generation electrochemical devices. Importantly, the ability to transport both electronic and ionic charge carriers is intimately linked to processing conditions and morphology. This work reports the influence of humidity on the structure and conduction of a series of poly[3-(potassium-n-alkanoate) thiophene]s in the thin film regime. These materials were found to be highly resistive under anhydrous conditions but exhibited mixed ion-electron conduction as a function of increasing relative humidity. UV-Vis-NIR measurements provide evidence for water-assisted formation of alkanoate-stabilized polythiophene polaron states and thus generation of charge carriers for electronic conduction, wherein dissociation of potassium-alkanoate bonds leads to the enhanced ionic conductivity. Additionally, in-situ humidified synchrotron X-ray scattering experiments reveal the resiliency of the underling semicrystalline morphology to increasing relative humidity, which balances the extent of both electronic and ionic conductivity. Our results show the strong influence of humidity on mixed ion-electron conduction characteristics of conjugated polyelectrolytes in self-doped conditions. |
Friday, March 6, 2020 12:51PM - 1:03PM |
X34.00009: Charge Transport, Morphological Properties and Cooling Performance of Functionally Graded Semiconducting Polymer Thin Films as Organic Thermoelectrics Tengzhou Ma, Ban Dong, Joseph Walter Strzalka, Shrayesh Patel Molecularly doped semiconducting polymers have demonstrated great potential in organic thermoelectrics (TEs) for thermal energy management. While functionally graded materials (FGMs) where transport properties are spatially controlled have been proven to improve TE device performance, experimentally fabricating FGMs has been a challenging task. In this work, we utilize the facile processability to modulate electronic properties through molecular doping of conjugated polymers to fabricate and characterize FG thin films. We leverage sequential vapor doping of poly[2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene] (PBTTT) with 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) to fabricate one form of FGMs: continuously graded thin films. We observe the presence of a 5mm gradient across which doping level and transport properties vary continuously. We predict TE cooling performance based on our experimental results where cold side temperature (Tc) and coefficient of performance are calculated through linear constitutive relations coupled with conservation of charge and energy. The results demonstrate that Tc of graded samples are significantly improved compared to that of uniform profile. This study provides guidelines to further development on more complex FGMs. |
Friday, March 6, 2020 1:03PM - 1:15PM |
X34.00010: Modulating Spin Concentrations in Self-Doped Organic Molecules Daniel Powell, Luisa Whittaker-Brooks N-type doping methods in organic systems typically combine small ionizable species with a semiconductor scaffold in solution before casting the pair into films. How dopants distribute within the cast semiconductor is unpredictable. The distribution of dopants, which vary from small to very large in their relative sizes, may affect semiconductor continuity, grain boundaries, morphology and packing of the semiconductor, electronic state distribution near the Fermi-energy, and yield topological variations in the electronic structure. Direct comparisons between different doping concentrations can therefore be rather nebulous, making the selection of the proper dopant for a given organic semiconductor highly convoluted. These challenges may be mitigated using self-dopants, where the electron source is covalently attached to the semiconductor. We have investigated the effects of steric hinderance, counterions, and dopant/semiconductor proximity on the efficiency of self-doping in a variety of perylene diimides. We believe our findings offer design considerations for the fabrication of effective self-dopants in n-type organic semiconductors. |
Friday, March 6, 2020 1:15PM - 1:27PM |
X34.00011: Bio-sourced Eumelanin Pigments: Charge Transport Properties and Beyond Manuel Reali, Abdelaziz Gouda, Clara Santato Green electronics recently opened new research avenues to use bio-sourced, biocompatible materials to limit the environmental footprint of electronics1-3. Within bio-sourced carbon-based materials, eumelanin, a black-brown conjugated biopigment, emerged as an excellent candidate for green electronics. |
Friday, March 6, 2020 1:27PM - 1:39PM |
X34.00012: Evaluation of environmental effects on the performance of 2,8-difluoro 5,11-bis(triethylsilylethynyl) anthradithiophene thin-film transistors Zafrullah Jagoo, Zachary Lamport, Oana D. Jurchescu, Laurie McNeil The electrical performance of organic transistors has been known to suffer from exposure to high moisture and oxygen levels. Reduction of the carrier mobility, threshold voltage shifting to more negative gate voltages and appearance of a hysteresis loop when scanning the gate voltage in the forward direction and then backwards are all manifestations of transistor deterioration. The worst possible outcome would be that the transistor is not longer functional after prolonged exposure to air. The study was conducted using a bottom-gate bottom-contact transistor with 2,8-difluoro 5,11-bis(triethylsilylethynyl) anthradithiophene (diF-TES ADT) as the active layer. The top surface of the semiconductor was uncovered and the device characteristics were measured at different oxygen and humidity levels. We found out that the organic thin-film transistor performed better electrically in the absence of water vapor and oxygen. Moreover, the degradation was reversible if the source of water vapor and oxygen was removed. This demonstrate the importance of encapsulation in organic semiconductor devices. |
Friday, March 6, 2020 1:39PM - 1:51PM |
X34.00013: Bio-sourced, potentially biodegradable materials for fast response moisture sensors Abdelaziz Gouda, Manuel Reali, Clara Santato Humidity is a very important physical parameter that plays an imperative role in technology and human activity. Researchers are paying more attention to develop moisture-responsive materials with outstanding characteristics such as high sensitivity, wide humidity detection range, fast response and short recovery times to keep pace with the on-going development in technology. Abundant, bio-sourced and biodegradable organic materials, such as melanin, are needed to enable the development of eco-designed technologies that alleviate the environmental footprint of the electronics sector. Melanin is a ubiquitous biomacromolecule with diverse functions including hydration dependent electrical response [1], photoresponse [2], antioxidant [3] , metal chelation [4], and free radical scavenging [5]. Melanin originates from the oxidative polymerization of (5,6)-dihydroxindole (DHI) and (5,6)-dihydroxindole 2-carboxyl acid (DHICA) building blocks [6]. DHI-melanin features ordered, conjugated structure with better electrical conductivity with respect to DHICA-melanin [5]. Herein, we investigate DHI-melanin and DHI-DHICA melanin thin films, spin coated and polymerized on technologically relevant and potentially biodegradable substrates, as active layers for fast response moisture sensors. |
Friday, March 6, 2020 1:51PM - 2:03PM |
X34.00014: Effects of Molecular Weight and Annealing on Charge Carrier Concentration in Thin PANI-CSA Films Arun Kumar Agarwal, Siddhartha Panda PANI-CSA thin films have shown promising results like higher temperature sensitivities (Ahmad et al, J. Appl. Polym. Sci. 2013) and overcoming limitations of Wiedemann-Franz law (Jin et al, J. Phys. D: Appl. Phys. 2010) hence, can be used in flexible wearable sensors, thermoelectric devices. However, charge transport in PANI-CSA thin films is not very well understood. Effect of doping on electrical conductivity (σ) in PANI-CSA, effect of molecular weight (MW) on mobility (μ) in RR-P3HT (Zhang et al, Jour. of Amer. Chem. Soc. 2006) and change in grain size on annealing in P3HT:PCBM (Beal et al, Macromolecules 2010) have been reported. However, there is no study on effect of MW on charge carrier concentration (n) in annealed PANI-CSA thin films. PANI-CSA thin films (~50-70nm) were fabricated with different MW of PANI-EB. Their σ was checked before and after annealing which showed a strong dependence on MW. Annealing decreased σ for all films but effect was more prominent at lower MW. AFM was done to map morphological changes with MW and annealing. DC Hall measurements were done to measure μ but were inconclusive due to low μ (Yamada et al, Synth. Met. 2019) hence, AC Hall measurements were done which indicated that the change in σ has two contributors; change in μ and change in n. |
Friday, March 6, 2020 2:03PM - 2:15PM |
X34.00015: Effects of concentration and local structure on charge trapping in polymer electrets with amine-based substituents. Evan Plunkett, Qingyang Zhang, Chen Chi, Howard Edan Katz, Daniel Reich Thin film polymer dielectrics with controllable electronic properties are of considerable interest for applications in organo-electronic systems. We use amine-based moieties in thin film polystyrene dielectrics to modify electron and hole trap states and densities. When chemically bound to polymers and also when introduced as free additives, these moieties induce changes in static potential differences that modify the behavior of adjacent electronic materials. For example, N,N’-diphenyl-N,N’-di-p-tolybenzene-1,4-diamine in polystyrene exhibited threshold voltage shifts up to ΔVth=O(50V) after application of static electric fields as measured in pentacene-based OFETs. Films with free additive concentration in the range of 1-3% showed a strongly concentration dependent stability in Vth, in contrast to polystyrene systems with tethered amines. Stability is higher at lower amine concentrations suggesting clustering of additives is an important effect in these systems. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700