Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session Q33: Organic Optoelectronic Devices: Design and PerformanceFocus
|
Hide Abstracts |
Sponsoring Units: DPOLY DSOFT DMP FIAP Chair: Kyungtae Kim, Los Alamos National Laboratory Room: Room 225 |
Wednesday, March 8, 2023 3:00PM - 3:36PM |
Q33.00001: Active Material Design for Mechanically-Robust, Efficient Polymer Solar Cells Invited Speaker: Bumjoon J Kim Considering the technical standards (e.g., mechanical robustness) required for wearable electronics, which are promising application platforms for organic solar cells, the development of fully stretchable OSCs (f-SOSCs) needs to be accelerated. First, the mechanical requirements of f-SOSCs, in terms of tensile and cohesion/adhesion properties, are summarized along with the experimental methods to evaluate those properties. Second, examples to make each layer of f-SOSCs stretchable and efficient are discussed, emphasizing strategies to simultaneously enhance the photovoltaic and mechanical properties of the active layer. For example, I present material design strategies to enhance the mechanical robustness of the PSCs as well as their power conversion efficiencies (PCEs); i) controlling molecular weights (MWs) of the polymer acceptors (PA), ii) incorporating a high-MW PA as an electro-active additive into binary blends, and iii) enhancing molecular miscibility between donor-acceptor in their blends. With these contributions, the f-SOSCs with over 12% PCE and excellent stretchability is developed. |
Wednesday, March 8, 2023 3:36PM - 3:48PM |
Q33.00002: Radical Polymer-based Mixed Conductors and Their Application to Bioelectronic Ocular Sensors Bryan W Boudouris, Ho Joong Kim Optoelectronically active polymers have made critical inroads in many solid-state electronic devices (e.g., organic field-effect transistors), and excitingly, macromolecules capable of providing mixed electronic and ionic conduction offer unique opportunities in many application areas including bioelectronic devices. Here, we first describe how a blend of a common conjugated polymer, poly(3-hexylthiophene) (P3HT), and a radical polymer (i.e., a macromolecule with a nonconjugated backbone and with stable open-shell sites on its pendant groups), poly(4-glycidyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl) (PTEO), allows for the creation of high-performance organic electrochemical transistors (OECTs) through a unique mixed conduction mechanism where the phase separation of the thin film polymer blend allows for discrete transport regimes between the conjugated polymer and radical polymer phases. Second, we will discuss how this type of archetype can be translated to biomedical device applications through a practical demonstration of a stretchable and flexible polymer-based biosensor. This bioelectronic device is inkjet-printed atop a commercial soft contact lens in a high-throughput manner, and our electroretinogram (ERG) sensor shows performance that is superior to current clinical gold standards in human subjects. In this way, we couple the physics of the polymer system to translational performance to demonstrate clear patient impact. |
Wednesday, March 8, 2023 3:48PM - 4:00PM |
Q33.00003: Evidence of pure spin-current and first organic Spin-Valve based on non-conjugated radical polymer glass Hamas U Tahir, Carsten Flores-Hansen, Sheng-Ning Hsu, Zihao Liang, Neil R Dilley, Brett M Savoie, Bryan W Boudouris Organic radicals with unpaired electrons have attracted burgeoning attention due to their intriguing technological applications in organic electronics, organic radical batteries, optoelectronics, electrochemical systems, and organic spintronic and magnetic devices. While significant efforts have developed magnetic and spin-correlated electronic properties, evaluating the subtle interplay with spins and spin-dependent transport in these materials is barely explored. The effect of external magnetic field on device resistance (i.e,, magnetoresistance) is one such property that aims at explaining how radical spin couples with externally applied magnetic and electric fields, however it is only limited to closed-shell conjugated polymers and single-molecule based radical junctions. Thus, there is a critical need to discover new classes of materials that could provide coexisting system of intrinsic electrical conductivity and magnetism favorable for spintronic applications. Here we show that poly(4-glycidyloxy-2,2,6,6-tetramethylpiperidine-1- oxyl) (PTEO), a non-conjugated radical polymer, exhibits excellent spin-filtering property upon annealing above its glass transition temperature that manifests as giant magnetoresistance effect (~ 80 %) at T = 4.2 K. As the temperature is increased, the magnitude of magnetoresistance decreases and (~ 5 %) is observed at T = 30 K. The observed giant magnetoresistance effect is attributed to increased intermolecular spin-spin interactions upon annealing that promotes spin-aligned transport. Moreover, we employ ferromagnetic resonance spin pumping in a ferromagnet/ PTEO/ non-magnetic spin-sink trilayer to demonstrate the importance of PTEO in carrying pure spin-current that results in large inverse spin hall effect (ISHE) voltages that is difficult to achieve with organic systems. Specifically, our effort demonstrates the coupled materials and device characterizations that are necessary to establish the fundamental structure-function design rules of this underexplored class of materials and thereby paves the way for radical polymer based spintronic applications. |
Wednesday, March 8, 2023 4:00PM - 4:12PM |
Q33.00004: Local chemical enhancement and gating of organic mixed ionic-electronic transport Brian A Collins, Tamanna T Khan, Terry McAfee, Awwad Alotaibi, Thomas Ferron Superior properties in organic mixed ionic-electronic conductors (OMIECs) over inorganic counterparts have inspired intense interest for many exciting applications. However, slow ion transport in these materials continues to limit their application in these technologies. Here we demonstrate that hydrophilic molecules local to an interfacial OMIEC nanochannel can accelerate ion transport with record ion mobilities surpassing electrophoretic transport by more than an order of magnitude. Furthermore, ion access to this interfacial channel can be gated through local surface energy. We apply this mechanism in a novel sensing device, which electronically detects and characterizes chemical reaction dynamics local to the buried channel. The ability to enhance ion transport at the nanoscale in OMIECs as well as control ion transport through local chemical signaling enables new functionalities for printable, stretchable, and biocompatible mixed conduction devices. |
Wednesday, March 8, 2023 4:12PM - 4:24PM |
Q33.00005: Impact of molecular weight and size distribution on the performance of PEDOT:PSS in organic electrochemical transistors Laure Kayser Organic electrochemical transistors (OECTs) are gaining momentum in biosensing applications for their ability to effectively transduce ionic signals from biological processes to electronic signals readable using conventional electronics. OECT devices rely on the use of organic mixed ionic-electronic conductors (OMIECs) as channel materials exposed to an aqueous electrolyte. The most commonly used OMIEC for OECT is the commercially available polyelectrolyte complex PEDOT:PSS, previously extensively used as an organic conductor and anti-static coating in “dry” conditions. Yet, key molecular features, such as molecular weight and size distribution, in this complex material are kept a trade secret by the manufacturer, preventing the establishment of important structure-property relationships. In this presentation, I will share how we used controlled radical polymerization to synthesize PSS with precise molecular weights and dispersity to establish their effect on the performance of PEDOT:PSS in OECTs [Lo et al. Polym. Chem., 2022, 13, 2707]. In particular, we found that the conductivity of PEDOT:PSS under “dry” conditions is correlated to the molecular weight of PSS, but independent of the dispersity. In the presence of an electrolyte, however, the molecular weight has little effect on the capacitance and OECT transconductance, but dispersity does. A broad dispersity (1.7 vs 1.1) leads to a four time increase in OECT performance. We correlated these findings to differences in film morphology. |
Wednesday, March 8, 2023 4:24PM - 4:36PM |
Q33.00006: Investigating Mass and Charge Transport in Organic Electrochemical Transistors for Use as Explosives Sensors. Aaron Woeppel, Bryan W Boudouris, Stephen Beaudoin Organic electrochemical transistors (OECTs) have attracted interest as they can be applied to a number of sensing and electronic challenges, and they provide a means to probe mass and charge transport present in electrolyte-gated systems. These phenomena can be altered by augmenting device architecture with either chemically selective or functionalized components. In particular, we supplement OECTs, which utilize poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) channels, with a molecularly imprinted polymer (MIP) barrier. These MIPs combine size exclusion and functional chemistry during their synthesis. These features render them highly selective to specific molecules and. The resulting architecture is then applied towards the detection of explosive species (i.e., energetic materials). The collective family of energetic materials contains a variety of species and includes covalently bound organics as well as ionically charged species. Aside from enabling selective detection, introducing such a barrier forces neutral molecules and electrically driven ionic species to competitively permeate through the barrier. Investigating these phenomena will help illuminate key molecule-pore binding principles and design strategies for new sensing arenas. |
Wednesday, March 8, 2023 4:36PM - 4:48PM |
Q33.00007: Water-processed Dielectric Layer for Eco-friendly High Performance Organic Thin Film Transistors Mi Ri Nae Lee, Yongju Lee, SWARUP BISWAS, Hyeok Kim People come into touch with and utilize technological gadgets and sensors on a regular basis. However, this causes them to degrade into electrical and electronic trash. There are numerous techniques for reducing these wastes, but one of them is to replace the standard oxide dielectric layer used in electronics with eco-friendly and economical materials. Although research has so far produced a device using components like cellulose, collagen, etc., it is difficult to develop a high-performance thin film transistor (TFT) working at a low voltage because to its relatively high phosphorous voltage [2]. This exposes the pinhole, which might result in a substantial leakage current. In this work, an organic thin film transistor with a dielectric layer was made using a substance known as gum arabic (GA). GA is a material manufactured from the Acacia Senegal tree, which grows in sub-Saharan Africa [3]. GA may be converted into an aqueous solution and has a high dielectric constant of k to 30 at 1 kHz [1]. As a result, we used DNTT, a p-type organic material, to develop an organic thin film transistor. This led to the realization of an organic thin film transistor with a hole mobility of at least 10 cm2/Vs. |
Wednesday, March 8, 2023 4:48PM - 5:00PM |
Q33.00008: Extending the measurement of domain purity in organic photovoltaic blends Peter Dudenas, Yilei Wu, Sebastian Scneider, Christina Cheng, Michael F Toney, Alberto Salleo, Zhenan Bao, Dean M DeLongchamp Resonant Soft X-ray Scattering (RSoXS) is an advanced structural characterization technique that combines small-angle x-ray scattering with soft x-ray spectroscopy to provide enhanced contrast and sensitivity to molecular orientation in soft matter thin films. Within the organic photovoltaic (OPV) community, the RSoXS technique is frequently employed to determine domain size and domain purity in blend films, which are often found to correlate with OPV power conversion efficiencies (PCE), with the common finding that increased purity leads to decreased electron-hole recombination and higher PCE. We will show that RSoXS contrast due to molecular orientation cannot be excluded from the measurement by energy selection alone, leading us to conclude that the conventional RSoXS purity measurement delivers a combination of compositional heterogeneity and orientational heterogeneity information. |
Wednesday, March 8, 2023 5:00PM - 5:12PM |
Q33.00009: Using discotic liquid crystals to prepare biaxially textured organic semiconductors Kushal Bagchi, Tadej Emersic, Zhongyang Wang, Wen Chen, Juan J De Pablo, Paul F Nealey Crystal texture plays a central role in determining the performance of organic electronic devices such as organic field effect transistors (OFETs). Current methods of controlling thin film crystal texture through solution processing are limited by stochastic nucleation. We report here a facile new method to create biaxially textured crystals of organic semiconductors by directing the self-assembly of the precursor discotic liquid crystalline phase. The columnar hexagonal (ColH) phase of HAT6 (2,3,6,7,10,11-Hexakis(hexyloxy)triphenylene) is biaxially aligned in lithographically fabricated microchannels consisting of cross-linked polystyrene (XPS) walls on silicon. Synchrotron grazing incidence wide angle X-ray scattering (GIWAXS) measurements reveal the direction of π stacking is perpendicular to the XPS walls. The biaxial alignment and the directionality of π stacking in the liquid crystalline phase is transferred to the crystalline phase by rapid quenching. As a significant fraction of organic semiconductors exhibit a liquid crystalline phase, we expect our method of creating textured crystals to be broadly applicable. |
Wednesday, March 8, 2023 5:12PM - 5:24PM |
Q33.00010: A circuit model approach for donor acceptor solar cells exhibiting disorder Cassandra Bogh, Ayla Osgood, Kathleen T Smith, Xinrui Zhu, Benjamin Zank, Dhandapani Venkataraman, Roderick C MacKenzie, Katherine Aidala, Alexi C Arango The Shockley diode model is often used to extract the shunt resistance, series resistance, and ideality of solar cells from current-voltage (IV) curves, and to model open circuit voltage under illumination. However, in a realistic model for solar cells consisting of materials exhibiting disorder, transport through disordered states does not necessarily follow Ohmic behavior because of the influence of space charge. Mark and Helfrich identified the current through organic crystals to follow a power law with voltage, where the exponent is proportional to the trap depth, but it is not clear if the model applies to amorphous thin film devices or donor-acceptor heterojunctions. Here, we present a new equivalent circuit for the dark IV curves of bilayer organic solar cells, which can accurately fit the IV curve across the entire voltage range, from low voltage through values substantially higher than open circuit. In the proposed circuit model, the dark current is represented by circuit elements that combine transport, shunting, and recombination, described by power laws. We validate the model with simulated data and experimental IV curves from devices with different acceptor layers. By better understanding how individual transport mechanisms combine to assemble into the total IV curve, we can extract information about disorder, energy level offsets, and parasitic effects within the solar cell, suggesting ways to improve future devices including perovskite solar cells. |
Wednesday, March 8, 2023 5:24PM - 5:36PM |
Q33.00011: Carrier Screening of Dopant Coulomb Interactions in Organic Electronics Zlatan Aksamija, Muhamed Duhandzic, Dhandapani Venkataraman, Michael Lu Diaz, Subhayan Samanta The importance of Coulomb interactions and their impact on the density of states (DOS) via dopant-induced disorder is now well established. However, previous studies of hopping transport within the Gaussian Disorder Model did not consider the role of screening of the interactions by the carriers. Here we implement screening in the Debye-Hückel formalism and calculate dopant-induced disorder with the Yukawa potential. Then we solve the Pauli Master Equation with Miller Abrahams hopping rates with states from the resulting doped and screened DOS. Our results show that screening has a significant impact on the Seebeck coefficient and shape of the DOS. The thermoelectric (TE) power factor increases almost by a factor of 2 at higher doping. We also observe that the log slope of the Seebeck coefficient plotted against the electrical conductivity for different doping concentrations, which was previously thought to have a universal value (-1/4), increases for a more energetically disordered system. Including screening we were able to reproduce and explain these curves obtained in measurements and connect the change in slope with change in structure of the host polymer. We conclude that carrier screening of dopant interactions plays an important role in transport and TE properties of polymers, especially at high doping concentrations. Our study refines the understanding of fundamental processes in doped polymers and enable their easier engineering for electronic, thermoelectric, and photovoltaic applications. |
Wednesday, March 8, 2023 5:36PM - 5:48PM |
Q33.00012: Designing High-Spin Small Organic Molecules for Optoelectronic Applications Neeraj Rai, Md Abdus Sabuj, Chinmoy Saha, Md Masrul Huda Polycyclic hydrocarbons with open-shell character are extensively studied due to their tunable molecular scaffold and electronic properties. However, design strategies delineating control of the ground electronic state from closed-shell to open-shell diradical to polyradical character are not well studied. Here, we report indacenodinaphthothiophene isomers fused with five-membered carbonaceous rings and dicyanomethylene groups to show either a high-spin ground state or a large diradical and tetraradical character with small singlet-triplet energy gaps, not observed in these polycyclic hydrocarbons. Density functional theory calculation indicates the syn- and anti-configurations have closed-shell ground-state with a large singlet-triplet energy gap. However, the linear configuration displays pure open-shell diradical and tetraradical characters with small hexaradical characters. This study shows a novel design strategy of polycyclic hydrocarbons with a large polyradical character, compelling synthetic targets for magnetic and spintronics materials. |
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