Bulletin of the American Physical Society
APS March Meeting 2018
Volume 63, Number 1
Monday–Friday, March 5–9, 2018; Los Angeles, California
Session F56: Organic Electronics and Photonics II: ApplicationsFocus
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Sponsoring Units: DPOLY DMP Chair: Stephanie Lee, Stevens Institute of Technology Room: LACC 515B |
Tuesday, March 6, 2018 11:15AM - 11:51AM |
F56.00001: The impact of organic phototransistors on large area image sensors Invited Speaker: Ana Arias This abstract not available. |
Tuesday, March 6, 2018 11:51AM - 12:03PM |
F56.00002: Effect of Radical Polymer Doping on the Carbon Nanotube Transistors Yongho Joo, Mukherjee Sanjoy, Bryan Boudouris Single-walled carbon nanotubes (SWCNTs) have shown exceptional promise for electronic applications due to a complementary set of desirable properties. Due to adventitious atmospheric p-type doping of SWCNT thin film transistors (TFTs) under ambient conditions, p-type unipolar devices are easily attained and have been the focus of extensive optimization and integration. However, n-type doping of SWCNTs for ambipolar transistor operation has proven to be considerably more challenging. Here, we introduce here the use of an aliphatic polymer as an n-type dopant for producing ambipolar SWCNT TFTs. We have systematically studied the effect of doping with the use of aliphatic polymers bearing robust organic radicals as pendant groups on the macromolecular backbone. The large population of the radical redox sites allows for a significant amount of doping to occur between the radical polymers and the SWCNTs, and this affords the ability to tune the TFT performance. Thus, this combination of physical chemistry and device physics allows for never-before-seen behavior in SWCNT-radical polymer composite materials. |
Tuesday, March 6, 2018 12:03PM - 12:15PM |
F56.00003: Intrinsic conductivity mechanisms of radical polymer films with conjugated and non-conjugated backbones Albert Park, Yiren Zhang, Alicia Cintora, Stephen McMillan, Nicholas Harmon, Austin Moehle, Michael Flatté, Christopher Ober, Gregory Fuchs Radical polymers, which incorporate a stable radical pendent group such as 2,2,6,6-tetramethyl pipiridine-1-oxyl (TEMPO), form as class of non-toxic, environmentally friendly materials for battery electrodes. Their conductivity in the solid phase, while critical for battery electrode applications because of the need to collect current, have been controversial. Here we discuss our study of DC conductivity in several species of radical polymers. First, we prepared poly(2,2,6,6-tetramethylpiperidinyloxy methacrylate) (PTMA) using several synthetic methods to examine if the previously proposed redox hopping mechanism is sensitive to the preparation details. We found that PTMA is an insulator, implying that few radical sites participate in conductivity. In search of a radical polymer with higher conductivity, we also investigated the properties of a radical polymer with a conjugated backbone. Our results show that although introducing conjugation to the backbone is a route to introduce conductivity to a radical polymer, the steric hindrance from the TEMPO groups limit the size of the ordered conjugated crystal domains and thus severely reduce the conductivity as compared to the conjugated backbone without TEMPO. |
Tuesday, March 6, 2018 12:15PM - 12:27PM |
F56.00004: Mixed ionic/electronic conduction in a oligoethyleneglycol-terminated oligothiophene rod-coil oligomer Ban Dong, Ziwei Liu, Christopher Ober, Shrayesh Patel, Paul Nealey Developing and studying materials that conduct both electronic and ionic charges on the nanometer length scale is of considerable interest for a wide range of energy harvesting and storage applications. In this work, we report the design, synthesis and characterization of tetraethyleneglycol monomethyl ether-terminated quaterthiophene rod-coil oligomer 4T/PEG4 thin film that shows both ionic and electronic conduction characteristics. At room temperature, 4T/PEG4 only exhibits ionic conductivity on the order of 10-5S/cm upon blending with LiTFSI at the optimum doping concentration r = 0.1. The electronic conduction can be introduced into the bolaamphiphile by doping F4TCNQ into LiTFSI-doped 4T/PEG4 thin film via vapor doping method. The electronic conductivity as high as 2 x 10-3 S/cm in 4T/PEG4 can be achieved without sacrificing ionic conductivity. UV-vis absorption spectroscopy measurement indicates that charge transfer complex is the dominant doping mechanism, suggesting the formation of co-crystal between F4TCNQ and the quaterthiophene unit of 4T/PEG4. Our results show that 4T/PEG4 is a promising candidate to study the combination of both ionic and electronic conductivities in a single materials system. |
Tuesday, March 6, 2018 12:27PM - 1:03PM |
F56.00005: Thermoelectric Properties of Semiconducting Polymers Invited Speaker: Michael Chabinyc An emerging application of semiconducting polymers is as thermoelectric materials. The performance of thermoelectrics is related to their electrical conductivity, thermopower and thermal conductivity. These properties all rely on careful control of the carrier concentration by electrical doping. In many polymers, an empirical power-law relationship is found between the thermopower and electrical conductivity. We will discuss our efforts to model the connection between the electrical conductivity and thermopower of semiconducting polymers using poly(3-hexylthiophene) and a thienothiophene-based polymer, PBTTT. We find that electrical conductivity of doped semiconducting polymers is a strong function of morphology, whereas the thermopower is more weakly dependent on structural order. Temperature-dependent conductivity and thermopower measurements are in reasonable agreement with a recently proposed model that uses a power-law conductivity function to describe their behavior. This model also suggests a power law form for the electronic density of states of doped semiconducting polymers near the Fermi level. The implications of this behavior for improvement of the thermoelectric properties of polymers will be discussed. |
Tuesday, March 6, 2018 1:03PM - 1:15PM |
F56.00006: Thermal Conductivity in Crystalline Polythiophene Using ab-initio Anharmonic Lattice Dynamics Peishi Cheng, Nina Shulumba, Austin Minnich Bulk polymers typically have poor thermal conductivity, but the intrinsic thermal conductivities of polymer chains and crystals can be very high, exceeding those of many metals. Recent measurements have shown that even semi-crystalline polymers with complex unit cells still achieve high thermal conductivity, contrary to the typical guidelines for effective thermal transport which prescribe a simple unit cell with a small number of atoms. In this work, we explore the thermal conductivity and three-phonon scattering pathways of polythiophene using anharmonic lattice dynamics with ab-initio, finite temperature force constants. Lattice dynamics allows us to look in detail at the scattering phase space and three-phonon interaction strength for each individual mode, to identify which vibrations contribute most to thermal conductivity and why. Knowledge of the physical features which determine the thermal transport aids in establishing molecular-scale design principles for thermally conductive polymers. |
Tuesday, March 6, 2018 1:15PM - 1:27PM |
F56.00007: Electro-polymerization of PEDOT with a three-armed conjugated crosslinker leads to enhanced charge transport Junseop Lee, Shrayesh Patel Poly(ethylenedioxythiophene)-based polymers (PEDOT) have emerged as versatile materials for transparent conducting electrodes, electronics for biointerfacing, and organic thermoelectrics – interconversion of heat and electricity. Here, we report on the co-electropolymerization of EDOT with a three-armed conjugated crosslinker TTB (1,3,5,-tri(2-thienyl)-benzene). Through a systematic variation of TTB concentration, we show the incorporation of low levels of TTB leads to enhanced electronic conductivity relative to neat electropolymerized PEDOT films. We attribute the increase in electronic conductivity to enhanced pi-pi interaction of the polymer chains and enhanced conjugation with the TTB crosslinking unit. In addition, to probe the utility as conductive electrode films, electrochemical ac impedance spectroscopy reveals that the incorporation of TTB leads to reduced film impedance in electrolytic solutions at low and high frequencies. Lastly, tuning the charge carrier concentration through controlled oxidation, we show an enhancement in the thermoelectric power factor at low TTB concentrations. Overall, our work conveys the utility of using a three-armed conjugated crosslinker for enhanced charge transport in PEDOT-based platforms. |
Tuesday, March 6, 2018 1:27PM - 1:39PM |
F56.00008: Abstract Withdrawn
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Tuesday, March 6, 2018 1:39PM - 1:51PM |
F56.00009: Tunable motional narrowing of polaron charge carrier hyperfine field distributions in ethylene glycol doped poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) Mandefro Teferi, Jonathan Ogle, Gajadhar Joshi, Shirin Jamali, Douglas Baird, Hans Malissa, Luisa Whittaker-Brooks, Christoph Boehme The conductivity of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) thin films can be enhanced by adding ethylene glycol (EG) to its aqueous solution. We have investigated the effect of this on charge carrier (polaron) spin states by measuring multifrequency continuous wave (cw) and pulsed (p) electrically detected magnetic resonance (EDMR) on PEDOT:PSS based bipolar injection devices with varying EG content [1]. At T=300K, all devices show nearly Ohmic behavior whose conductivity increases with EG concentration. At T=5K, all devices reveal diode-like behavior. Using EDMR, we have been able to spectroscopically separate the hyperfine (HF) interaction from spin-orbit interaction induced g-factor distributions. We observe a reduction of the HF fields with increasing EG content, yet, at the same time, an increase of the spin coherence times T2, in spite of the increased charge carrier mobility. This behavior is consistent with motional narrowing of the observed resonance lines and it shows that EG doping can be used to tune the effective local hyperfine fields. [1] G. Joshi et al., Appl. Phys. Lett. 109, 103303 (2016). |
Tuesday, March 6, 2018 1:51PM - 2:03PM |
F56.00010: Electronic structure of dipeptides in the gas-phase and as an adsorbed monolayer Soumyajit Sarkar, Cunlan Guo, Sivan Refaely-Abramson, David Egger, Tatyana Bendikov, Keiichirou Yonezawa, Yosuke Suda, Takuma Yamaguchi, Israel Pecht, Satoshi Kera, Nobuo Ueno, Mudi Sheves, Leeor Kronik, D Cahen The electronic properties of peptide molecules can change considerably with their structure, allowing for diverse design possibilities of peptide-based molecular electronic devices. We explore the effect of the side-chain on the peptide’s electronic properties, by using both experimental and computational tools to detect the energy levels of the electronic structure of two model peptides - 2Ala and 2Trp - as well as these peptides with a 3-mercaptopropionic acid linker which allows them to form monolayers on Au surface. Specifically, we compare experimental gas phase ultraviolet photoemission spectroscopy measurements with density functional theory-based computational results, using the optimally-tuned range-separated hybrid functional formalism. By analyzing differences in frontier energy levels and molecular orbitals between peptides in gas-phase and in a monolayer, we find that the electronic properties of the peptide side-chain are maintained during binding of the peptide to the gold substrate. This indicates that the energy barrier for the peptide electron transport can be tuned by the amino acid compositions, which suggests a route for structural design of peptide-based electronic devices. |
Tuesday, March 6, 2018 2:03PM - 2:15PM |
F56.00011: Tunable effective resistance and capacitance of Ni ion-complex in Ni-DNA Chia-Ching Chang, Yu-Chang Chen, Wen-Bin Jian, Chiun-Jye Yuan, Massimiliano Di Ventra Metal-ion chains are nanowires with potential applications in nano-electronics and molecular computing. However, it is difficult to create a frame-free metal-ion chain. DNA is a natural nanowire, which can chelate metal ions, such as nickel ions, with its own base pairs. In this study, we discuss the physical properties of a two-micrometer long Ni-DNA. We show that by applying an appropriate external bias the resistance and capacitance of Ni-DNA can be changed and exhibites both memristor and memcapacitor effects. Simulations of these Ni-DNA devices indicates that the resistance and capacitance changes are the result of voltage-driven changes to the nickel ion redox state. We conclude that Ni-DNA is a good candidate for nano-electronics and molecular computing applications [1]. |
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