Academic literature on the topic 'Ambipolar Charge Transport'
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Journal articles on the topic "Ambipolar Charge Transport"
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Roy, V. A. L., Ella Lai-Ming Wong, Ben Chi-Bun Ko, et al. "Ambipolar Charge Transport in DNA Molecules." Advanced Materials 20, no. 7 (2008): 1258–62. http://dx.doi.org/10.1002/adma.200701179.
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Khademi, S., J. Y. Song, P. B. Wyatt, T. Kreouzis, and W. P. Gillin. "Ambipolar Charge Transport in “Traditional” Organic Hole Transport Layers." Advanced Materials 24, no. 17 (2012): 2278–83. http://dx.doi.org/10.1002/adma.201103830.
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Reig, Marta, Gintautas Bagdziunas, Dmytro Volyniuk, Juozas V. Grazulevicius, and Dolores Velasco. "Tuning the ambipolar charge transport properties of tricyanovinyl-substituted carbazole-based materials." Physical Chemistry Chemical Physics 19, no. 9 (2017): 6721–30. http://dx.doi.org/10.1039/c6cp08078b.
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The ambipolar charge transport properties of a series of push–pull carbazole-based semiconductors are here evaluated. The ambipolar characteristics depend on the supramolecular organization. Experimental results were confirmed and justified through the X-ray analysis of single crystals and by theoretical calculations.
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Liu, Ke, Cheng-Li Song, Ye-Cheng Zhou, et al. "Tuning the ambipolar charge transport properties of N-heteropentacenes by their frontier molecular orbital energy levels." Journal of Materials Chemistry C 3, no. 16 (2015): 4188–96. http://dx.doi.org/10.1039/c4tc02859g.
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Tuning the ambipolar performance: carefully designed N-heteropentacenes realized fine tuning of their HOMOs and LUMOs, which dramatically affected their ambipolar transport performance in field-effect transistors.
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Jiang, Hui, Jun Ye, Peng Hu, et al. "Growth direction dependent separate-channel charge transport in the organic weak charge-transfer co-crystal of anthracene–DTTCNQ." Materials Horizons 9, no. 3 (2022): 1057–67. http://dx.doi.org/10.1039/d1mh01767e.
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Gong, Xiong, Yali Yang, and Steven Xiao. "Ambipolar Charge Transport in Polymer Light-Emitting Diodes." Journal of Physical Chemistry C 113, no. 17 (2009): 7398–404. http://dx.doi.org/10.1021/jp811396j.
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Reig, Marta, Cristian Gozálvez, Vygintas Jankauskas, et al. "Stable All-Organic Radicals with Ambipolar Charge Transport." Chemistry - A European Journal 22, no. 51 (2016): 18551–58. http://dx.doi.org/10.1002/chem.201603723.
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Hasenburg, Franziska H., Kun-Han Lin, Bas van der Zee, Paul W. M. Blom, Denis Andrienko, and Gert-Jan A. H. Wetzelaer. "Ambipolar charge transport in a non-fullerene acceptor." APL Materials 11, no. 2 (2023): 021105. http://dx.doi.org/10.1063/5.0137073.
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Charge transport is one of the key factors in the operation of organic solar cells. Here, we investigate the electron and hole transport in the non-fullerene acceptor (NFA) IT-4F, by a combination of space-charge-limited current measurements and multiscale molecular simulations. The electron and hole mobilities are fairly balanced, amounting to 2.9 × 10−4 cm2 V−1 s−1 for electrons and 2.0 × 10−5 cm2 V−1 s−1 for holes. Orientational ordering and electronic couplings facilitate a better charge-percolating network for electrons than for holes, while ambipolarity itself is due to sufficiently high electron affinity and low ionization energy typical for narrow-gap NFAs. Our findings provide a molecular-level understanding of the balanced hole and electron transport in an archetypical NFA, which may play a key role in exciton diffusion and photogenerated hole transfer in organic solar cells.
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Bala, Indu, Wan-Yun Yang, Santosh Prasad Gupta, et al. "Room temperature discotic liquid crystalline triphenylene-pentaalkynylbenzene dyads as an emitter in blue OLEDs and their charge transfer complexes with ambipolar charge transport behaviour." Journal of Materials Chemistry C 7, no. 19 (2019): 5724–38. http://dx.doi.org/10.1039/c9tc01178a.
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Kang, Evan S. H., Shangzhi Chen, Vedran Đerek, Carl Hägglund, Eric D. Głowacki, and Magnus P. Jonsson. "Charge transport in phthalocyanine thin-film transistors coupled with Fabry–Perot cavities." Journal of Materials Chemistry C 9, no. 7 (2021): 2368–74. http://dx.doi.org/10.1039/d0tc05418f.
Full textDissertations / Theses on the topic "Ambipolar Charge Transport"
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Zuniga, Carlos A. "Solution-processable charge transport layers for phosphorescent OLEDs." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/43671.
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The development of new charge transport materials for use in phosphorescent organic light-emitting diodes (OLEDs) remains an important area of research. In this thesis, several examples of carbazole-containing norbornene-based side-chain polymers were synthesized and studied. In addition, several examples of ambipolar transport moieties were produced by combining hole- (carbazole) and electron- (oxadiazole or triazole) transport groups and examined as both small molecules and as norbornene-based side-chain polymers. UV-visible absorption, fluorescence spectroscopy, cyclic voltammetry, and other methods were used to evaluate the properties of the charge transport materials for use as hole- and/or host layers. It was found that side-functionalization produced polymers with photophysical and electrochemical properties corresponding to the charge transport side groups attached. In addition, several crosslinkable hole-transporting materials (copolymer or small molecule-based) incorporating either benzocyclobutenes, trifluorovinyl ethers, oxetanes, or bis(styrene)s were developed. Thin-films of the crosslinkable materials were shown to be readily insolubilized by thermal treatment permitting the deposition of a subsequent layer from solution onto the crosslinked layer. OLEDs fabricated using several of these materials produced efficient devices. Overall, it was shown that side-chain functionalization can be used to afford solution-processable charge transport polymers where the properties are determined mainly by the side group attached. As such, this approach could be extended to additional examples of charge transport moieties.
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Psaltis, Steven Timothy Peter. "Multicomponent charge transport in electrolyte solutions." Thesis, Queensland University of Technology, 2012. https://eprints.qut.edu.au/60964/1/Steven_Psaltis_Thesis.pdf.
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The work presented in this thesis investigates the mathematical modelling of charge transport in electrolyte solutions, within the nanoporous structures of electrochemical devices. We compare two approaches found in the literature, by developing onedimensional transport models based on the Nernst-Planck and Maxwell-Stefan equations.
The development of the Nernst-Planck equations relies on the assumption that the solution is infinitely dilute. However, this is typically not the case for the electrolyte solutions found within electrochemical devices. Furthermore, ionic concentrations much higher than those of the bulk concentrations can be obtained near the electrode/electrolyte interfaces due to the development of an electric double layer. Hence, multicomponent interactions which are neglected by the Nernst-Planck equations may become important.
The Maxwell-Stefan equations account for these multicomponent interactions, and thus they should provide a more accurate representation of transport in electrolyte solutions. To allow for the effects of the electric double layer in both the Nernst-Planck and Maxwell-Stefan equations, we do not assume local electroneutrality in the solution.
Instead, we model the electrostatic potential as a continuously varying function, by way of Poisson’s equation. Importantly, we show that for a ternary electrolyte solution at high interfacial concentrations, the Maxwell-Stefan equations predict behaviour that is not recovered from the Nernst-Planck equations.
The main difficulty in the application of the Maxwell-Stefan equations to charge transport in electrolyte solutions is knowledge of the transport parameters. In this work, we apply molecular dynamics simulations to obtain the required diffusivities, and thus we are able to incorporate microscopic behaviour into a continuum scale model. This is important due to the small size scales we are concerned with, as we are still able to retain the computational efficiency of continuum modelling. This approach provides an avenue by which the microscopic behaviour may ultimately be incorporated into a full device-scale model.
The one-dimensional Maxwell-Stefan model is extended to two dimensions, representing an important first step for developing a fully-coupled interfacial charge transport model for electrochemical devices. It allows us to begin investigation into ambipolar diffusion effects, where the motion of the ions in the electrolyte is affected by the transport of electrons in the electrode. As we do not consider modelling in the solid phase in this work, this is simulated by applying a time-varying potential to one interface of our two-dimensional computational domain, thus allowing a flow field to develop in the electrolyte. Our model facilitates the observation of the transport of ions near the electrode/electrolyte interface. For the simulations considered in this work, we show that while there is some motion in the direction parallel to the interface, the interfacial coupling is not sufficient for the ions in solution to be "dragged" along the interface for long distances.
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Polander, Lauren E. "Organic charge-transport materials based on oligothiophene and naphthalene diimide: towards ambipolar and air-stable n-channel organic field-effect transistors." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/45849.
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To better understand the physical and electronic properties of donor and acceptor-based structures used in organic electronic applications, a variety of oligothiophene and naphthalene diimide-based small conjugated molecules were designed, synthesized, and characterized. The materials were initially synthesized using oxidative copper-chloride coupling reactions, palladium-catalyzed amination reactions, Friedal-Crafts acylations, Negishi coupling reactions, and Stille coupling reactions. Once isolated, the physical properties of the compounds were characterized through a combination of X-ray crystal structure, thermogravimetric analysis, differential scanning calorimetry, UV-vis. absorption spectroscopy, cyclic voltammetry, and differential pulse voltammetry, along with comparison to quantum-chemical calculations. In some cases, the radical cations or radical anions were generated by chemical oxidation and analyzed by vis-NIR spectroscopy. Furthermore, the electronic properties of the materials were investigated through incorporation as solution-processed active layers in organic field-effect transistors. Multiple examples exhibited hole- and / or electron-transport properties with electron mobility values of up to 1.5 cm²V⁻¹s⁻¹, which is among the highest yet reported for an n-channel OFET based on a solution-processed small molecule.
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Teng, Teng. "Semiconducting Materials Based on Donor/Acceptor Units for Optoelectronic Applications." Electronic Thesis or Diss., Sorbonne université, 2018. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2018SORUS452.pdf.
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Les semi-conducteurs cristaux liquides et les matériaux à faible gap sont deux familles de matériaux intéressants pour des applications dans le domaine de l’optoélectronique. Ils peuvent être utilisés dans de nombreux dispositifs électroniques différents tels que les cellules solaires organiques (OPV), les diodes électroluminescentes organiques (OLED) et les transistors organiques à effet de champ (OFET). Dans ce travail, nous nous sommes concentrés sur la conception et la synthèse de nouveaux matériaux semi-conducteurs constitués d’architectures donneur / accepteur qui présentent soit des propriétés de photoluminescence et de transport de charge élevées, soit un gap énergétique fable pour viser des matériaux ambipolaires. Les premières séries de matériaux sont des molécules organiques cristal liquides basées sur un cœur accepteur de benzothiadiazole et des groupes donneurs de type alcoxyphényle, avant de développer des structures plus complexes de type diade et triade. Les molécules à faible gap sont quant à elles constituées d’un cœur naphtalène diimide substitué par des unités comportant le benzothiadiazole. L'objectif était d'étudier leurs propriétés photophysiques, leurs propriétés de transport de charge et de corréler ces propriétés avec les propriétés structurelles des matériaux développés. Sur la base de nos résultats, nous avons démontré que ces molécules luminescentes possèdent des propriétés cristal liquide avec des structures lamellaires ou multilamellaires constituées de couches alternées d'unités fluorescentes ? Ces matériaux possèdent également une capacité élevée à transporter des charges, ce qui indique que ces composés ont un potentiel intéressant pour des applications en optoélectronique et en particulier pour des dispositifs type OFET. D’autre part, il a été démontré que les deux molécules à faible gap possèdent des propriétés de transport de charge de type n ou de type ambipolaire<br>Liquid crystalline semiconductors and narrow bandgap materials are two kinds of interesting materials for optoelectronic applications. They can be used in several type of organic electronic devices such as organic solar cells (OPV), Organic Light Emitting Diodes (OLED) and Organic Field Effect transistors (OFET). In this work, we focused on designing and synthesizing novel semiconducting materials based on donor/acceptor architectures which present either high photoluminescence and charge transport properties, or a narow bandgap for ambipolar charge transport. These materials are liquid crystalline molecules based on a benzothiadiazole acceptor core and alkoxyphenyl donor groups. The narrow bandgap molecules are based on a naphthalene diimide core and in this case flanked by benzothiadiazole units. The objective was to study their photophysical properties, charge transport properties, and to correlate this to the structural properties of the materials developed. Based on our results, we demostrated that these luminescent molecules possess liquid crystal properties with lamellar or multi-lamellar structures consisting of alternating layers of fluorescent units and high charge transport moieties. The charge transport properties measured of these compounds indicate that they have a potential for optoelectronic applications such as OFET devices. In addition, the two narrow bandgap molecules developed were found to exhibt n-type, and ambipolar charge transport properties
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Rekab, Wassima. "Multicomponent assemblies for organic electronics." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAF002.
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Mon travail de thèse porte sur l’assemblage supramoléculaire et le transport de charge des multi-composants utilisés dans le domaine de l’électronique à base organique. En particulier, l’étude et l’optimisation des transistors organiques à effet de champ (OFETs), des phototransistors, et des inverseurs organiques. Nous avons démontré que la température de recuit des dispositifs OFETs améliore les performances électriques d’un dérivé de fullerène (ICBA). Ces dispositifs dont les surfaces de SiO2 sont fonctionnalisées par OTS ou HMDS ont montrés des mobilités d’électrons de 0.1cm2V-1s-1, qui est la plus élevée par rapport à la littérature. Aussi, nous avons fabriqué des phototransistors à base de mono- et multifibres de PDIF-CN2 qui ont été optimisés par traitements de surfaces du diélectrique (HMDS ou OTS). Les propriétés optoélectroniques de ces dispositifs ont été comparées à ceux des dispositifs à base des couches minces déposés par spin-coating (éduction centrifuge). Nos dispositifs mono-fibres ont montré des valeurs de mobilité plus élevées (supérieure à 2 cm2V-1s-1) par rapport à ceux des multifibres et couches minces. Une telle efficacité de transport d’électrons est le résultat d’une cristallinité très élevée des fibres, qui permet une collecte efficace des excitons photo-générés qui se traduit par la plus haute sensibilité à la lumière (R) et photosensibilité (P) rapportées pour les phototransistors à base de mono-fibre supérieure à 2 × 103 AW-1, et 5 × 103 AW-1. Enfin, un polymère ambipolaire (DPPT-TT) a été utilisé lors de la fabrication de nouveaux dispositifs multifonctionnels par l’addition des molécules diaryléthènes (DAE_tBu et ou DAE_F), dont les propriétés électriques sont contrôlées par la lumière. Cette approche a permis un contrôle optique de gain en tension des inverseurs organiques, ces dispositifs multi-composants sont caractérisés par des gain en tensions très élevées (jusqu’au 504) comparés à ceux reportés dans la littérature (86). Ces travaux réalisés durant cette thèse offrent de nouvelles perspectives dans le domaine de l’optoélectronique et la conception des mémoires optiques<br>This thesis is focused on the investigation of supramolecular assemblies and the charge carriers transport across organic single, bi- and three-component materials, used as the active layer in organic field-effect transistors (OFET), phototransistors (OPT) and complementary inverters. We demonstrated that thermal annealing and duration has high impact in OFET performances based on a fullerene derivative called ICBA. The devices electron mobility enhanced upon HMDS and OTS treated SiO2 surface and reached 0.1 cm2V-1s-1, which is the highest reported value in literature. We have provided evidence for the influence of the order at the supramolecular level in the semiconducting material (PDIF-CN2) on the performance of OPTs. We compared solution processed single crystalline PDIF-CN2 fibers and multifiber assemblies with spin-coated thin films, which revealed that the former exhibited good electron mobility up to 2 cm2s-1V-1. The improved fiber crystallinity allows efficient collection of photogenerated excitons, results in the highest reported responsivity R (>5 × 103 AW-1), and photoswitching ratio P (>2 × 103), which are to date the highest reported in literature for PDI-single crystal OPTs. Finally, we have performed for the first time new multifunctional devices combining an ambipolar polymer (DPPT-TT) with inserted diarylethene molecules in its matrix. The fabricated OFET and organic complementary inverters were optically controlled. The resultant inverters gain values are tuned by ultraviolet and visible light irradiation, reaching 504, which is higher than those reported in literature (86). These findings qualify them as promising potential candidates for the construction of high-performance integrated logic circuits and memory chips
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Fall, Sadiara. "Etude du transport de charges dans les polymères semi-conducteurs à faible bande interdite et de son impact sur les performances photovoltaïques." Phd thesis, Université de Strasbourg, 2013. http://tel.archives-ouvertes.fr/tel-00975750.
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Le transport de charges dans une série de copolymères à faible bande interdite basés sur l'alternance de motifs riches en électrons (thiophène, thiénothiophène) et d'unités déficients en électrons (benzothiadiazole) et dans leurs mélanges avec un dérivé du fullerène (PCBM-C60) a été étudié. Les polymères sont différenciés par la structure moléculaire de leur coeur conjugué et par la nature, la position et la densité de leurs chaines latérales. Dans les polymères purs, la mobilité a été étudiée en fonction de la densité de charges par le biais de l'analyses de caractéristiques électriques de transistors à effet de champ et de dispositifs à un seul type de porteurs dont le courant est limité par la charge d'espace. En utilisant le modèle de transport de charges développé par Vissenberg et al., nous avons pu estimer le degré de désordre dans le film organique et corréler le transport de charge avec le degré d'ordre structural mesuré par la diffraction des Rayons-X. Ces polymères ont été conçus pour être utilisés dans la couche active des cellules solaires organiques. Grâce à l'étude du transport de charges dans les mélanges à différents ratios massiques polymères:fullerène, nous avons mis en évidence l'effet considérable de la structure moléculaire sur le ratio optimal polymère:fullerène. Aussi, nous avons pu montrer que la nature des chaînes latérales joue un rôle important dans l'obtention d'un chemin de percolation optimal à la conduction des électrons.
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Lüttich, Franziska. "Elektrische und morphologische Charakterisierung organischer Feldeffekttransistoren mit aufgedampften, gesprühten sowie aufgeschleuderten organischen Halbleitern." Doctoral thesis, Universitätsbibliothek Chemnitz, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-158832.
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In dieser Arbeit werden organische Feldeffekttransistoren (OFETs) aus den verschiedenen Materialien Manganphthalocyanin (MnPc), [6,6]Phenyl-C61-butansäuremethylester (PCBM), 6,13-Bis(triisopropylsilyethinyl)pentacen (TIPS-Pentacen) und N,N’-
Bis(n-octyl)-1,6-Dicyanoperylen-3,4:9,10-Bis(Dicarboximid) (PDI8-CN2) hergestellt. Dabei finden unterschiedliche Abscheidemethoden wie die Molekularstrahlabscheidung, die Ultraschallsprühbeschichtung und die Drehbeschichtung Anwendung. Die Morphologie sowie die Funktionsweise der Transistoren werden in Abhängigkeit von den Herstellungsparametern und bezüglich ihrer Stabilität gegenüber Lufteinfluss und elektrischer Belastung charakterisiert.
Durch Aufdampfen von MnPc konnten so zum ersten Mal ambipolare MnPc-OFETs hergestellt und charakterisiert werden. Die bestimmten Löcher- und Elektronenbeweglichkeiten bestätigen die Eignung von MnPc für die Anwendung in Spintronik-Bauelementen.
Desweiteren wird anhand gesprühter PCBM- und TIPS-Pentacen-OFETs gezeigt, dass die Ultraschallsprühbeschichtung eine geeignete Technik ist, um organische Halbleiter aus Lösung für die Verwendung in OFETs abzuscheiden. Die Abscheidung organischer Filme lässt sich mit einer Vielzahl an Parametern beeinflussen und die Funktionsweise von OFETs optimieren. In Verbindung mit den Untersuchungen aufgeschleuderter PDI8-CN2-OFETs konnte ein erheblicher Einfluss der Oberflächenenergie des verwendeten SiO2-Gateisolators auf die Korngröße im organischen Film festgestellt werden.
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Kanimozhi, K. Catherine. "Rational Design of Diketopyrrolopyrrole-Based Conjugated Polymers for Ambipolar Charge Transport." Thesis, 2013. http://etd.iisc.ernet.in/2005/3389.
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The present thesis is focused on the rational design of Diketopyrrolopyrrole based π- conjugated polymers for organic electronics. The thesis is organized into six different chapters and a brief description of the individual chapters is provided below.
Chapter 1 briefly describes the physics governing the electronic processes occurring in organic photovoltaics (OPVs) and organic field-effect transistors (OFETs) followed by design rules for the synthesis of conjugated polymers for organic electronics. Diketopyrrolopyrrole (DPP) based π-conjugated materials and their development in OPVs and OFETs have been highlighted.
Chapter 2 discusses the synthesis and characterization of a series of small molecules of DPP derivatives attached with different alkyl chains. Influence of side chains on the photophysical properties of these DPP derivatives have been studied by UV-visible spectroscopy and DFT calculations. Crystal structure studies revealed the effect of alkyl chains on the torsional angle, crystal packing, and intermolecular interactions such as π-π stacking.
Chapter 3 reports the synthesis of novel diketopyrrolopyrrole-diketopyrrolopyrrole (DPPDPP) based conjugated copolymers and their application in high mobility organic field-effect transistors. Effect of insulating alkyl chains on polymer thin film morphology, lamellar packing and π-π stacking interactions have been studied in detail. Investigation of OFET performance of these DPP-DPP copolymers with branched alkyl chains (N-CS2DPP-ODEH) resulted in low charge carrier mobilities as compared to the polymers (N-CS2DPP-ODHE) with linear alkyl chains. Polymer with triethylene glycol side chains (N-CS2DPP-ODTEG) exhibited a high field-effect electron mobility value of ~3 cm2V-1s-1 with a very low threshold voltage of ~2 V.
Chapter 4 investigates the effect of torsional angle on the intermolecular interactions and charge transport properties of diketopyrrolopyrrole (DPP) based polymers (PPDPP-OD-HE and PPDPP-OD-TEG). Grazing incidence x-ray diffraction studies shows the different orientation of the polymer crystallites and lamellar packing involved in polymer thin films. Investigation of OFETs evidenced the effect of torsional angle on the charge transport properties where the polymer with higher torsional angle PPDPP-OD-TEG resulted in high threshold voltage with less charge carrier mobility compared to the polymer with lower torsional angle (N-CS2DPP-OD-TEG).
Chapter 5 investigates the effect of photoactive material morphology on the solar cell device performance, and charge transfer kinetics by adding high boiling point processing additives. DPP based donor-acceptor (D-A) type low band gap polymers (PTDPPQ and PPDPPQ) have been synthesized and employed in bulk-heterojunction (BHJ) solar cells with the acceptor PC71BM. Addition of processing additive 1,8-diiodooctane (DIO) resulted in three order improvements in power conversion efficiency (PCE).
Chapter 6 describes the design and synthesis of two diketopyrrolopyrrole based copolymers (PPDPP-BBT and PTDPP-BBT) for their application in organic devices such as field-effect transistors and bulk-heterojunction solar cells. Investigation of OFET performance of these DPP based copolymers displayed hole mobilities in the order of 10-3 cm2V-1s-1. The semiconductor-dielectric interface has been characterized by capacitance-voltage, and Raman scattering methods.
In summary, the work presented in this thesis describes the synthesis and characterization of diketopyrrolopyrrole based new polymeric semiconductors. Effects of insulating side chains and torsional angle on the charge transport properties of these polymers in OFETs have been investigated. This work also describes the effect of solvent additives on the active layer morphology and BHJ solar cell device performance. The results described here show that these materials have potential application as active components in plastic electronics.
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Guo-EnYan and 顏國恩. "Studies of the ambipolar charge transport properties of organic thin film transistors." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/28212476416853749820.
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碩士<br>國立成功大學<br>光電科學與工程研究所<br>98<br>We have studied the ambipolar properties of pentacene-based organic thin-film transistors (Pen-OTFTs). In the first part, the contact resistance and channel resistance of Pen-OTFTs were investigated. In the second part, the ambipolar characteristics of Pen-OTFTs with different polymer modification layers were studied.
In part 1, we studied the influence of channel length on the ambipolar properties of Pen-OTFTs. With increasing channel length, we observed an increase in the saturated mobilities, and the threshold voltage becomes enlarged. In the saturation region, the contact resistance and channel resistance of Pen-OTFTs decreased with increasing gate bias or decreasing drain bias. Contact resistance plays an important role in the electrical properties of ambipolar pen-OTFTs.
Part 2 focused on an investigation of the influences of various different polymer modification layers on the ambipolar properties of Pen-OTFTs. The polymer modification layers were prepared via solution deposition with a spin-coating technique using different solvents that have various polymer concentrations. We found that the ambipolar properties are highly dependent on the polymer materials and preparation methods of these polymer modification layers. In contrast, we did not observe any considerable effects from the thickness of the modification layers on the ambipolar properties. Yet, we observed a significant influence of the thickness of the pentacene active layer on the ambipolar properties, including the threshold voltage, the threshold behaviors in the output current, and the off-current. On the other hand, when polymer modification layers were treated with oxygen plasma, the pen-OTFTs lost their ambipolar properties, thereby leaving unipolar hole properties. In addition, when the pentacene layers were treated with oxygen plasma, the non-ideal threshold behaviors in the output current were further improved.
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Chen, Li-Yin. "Study of Ambipolar Charge Transport in Organic Semiconductors Having Liquid Crystal Glass and Amorphous Phases." 2008. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-3001200815392100.
Full textBook chapters on the topic "Ambipolar Charge Transport"
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Chan, Yue. "CHAPTER 9. Mathematical Modelling and Simulations for Using Nanotubes and Graphene for Ultrafiltration and Molecular and Charge Transport." In Ambipolar Materials and Devices. Royal Society of Chemistry, 2020. http://dx.doi.org/10.1039/9781788019279-00214.
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Opitz, Andreas, and Wolfgang Brütting. "Ambipolar Charge-Carrier Transport in Molecular Field-Effect Transistors." In Physics of Organic Semiconductors. Wiley-VCH Verlag GmbH & Co. KGaA, 2013. http://dx.doi.org/10.1002/9783527654949.ch8.
Full textConference papers on the topic "Ambipolar Charge Transport"
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Sahoo, Smruti Ranjan, and Sridhar Sahu. "Ambipolar nature of dimethyl benzo difuran (DMBDF) molecule: A charge transport study." In DAE SOLID STATE PHYSICS SYMPOSIUM 2016. Author(s), 2017. http://dx.doi.org/10.1063/1.4980625.
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Schroeder, W. Andreas, Thomas S. Stark, Arthur L. Smir, and George C. Valley. "Hot Carrier Enhancement of Dember Photorefractive Space-Charge Fields in Zincblende Semiconductors." In Photorefractive Materials, Effects, and Devices II. Optica Publishing Group, 1991. http://dx.doi.org/10.1364/pmed.1991.mc5.
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We use a novel, nondegenerate, polarization-sensitive, transient-grating technique1 to monitor the picosecond dynamics of the photorefractive effect in undoped CdTe and InP:Fe at 960 nm. The technique circumvents the limited temporal resolution of the two-beam coupling geometry by using a time-delayed third probe pulse (with a duration of <5 psec) to read the gratings written in the semiconductor. The technique also exploits the crystal symmetry of zincblende semiconductors by using an optically induced anisotropy in the crystal index of refraction2 to separate the photorefractive gratings from the stronger, co-existing instantaneous bound-electronic and freecarrier gratings. In both semiconductors, the photorefractive effect is associated with the Dember field between mobile electron-hole pairs, in contrast to the more conventional photorefractive space-charge field connected with the separation of a mobile carriers species from a stationary, but oppositely charged, mid-gap state. In the undoped CdTe sample, which possesses no optically-active mid-gap levels, the electron-hole pairs are produced by two-photon absorption of 1.3 eV photons across the 1.44 eV band-gap of the semiconductor. The resultant ~1 eV excess carrier energy, which allows hot carrier transport to dominate the initial formation of the space-charge field, causes up to an order of magnitude enhancement in the photorefractive effect on picosecond timescales. After the carriers have cooled and the initial overshoot in the space-charge field has decayed, the photorefractive effect is observed to decay as the Dember field is destroyed by ambipolar diffusion of the electron-hole pairs across the grating period. In InP:Fe on the other hand, the electron-hole pairs are produced predominantly by direct single-photon band-to-band absorption into the band-tail of the semiconductor (band-gap ~1.35 eV), since the iron dopant only dominates the linear absorption at longer wavelengths. This means that the carriers are generated with little excess energy. Consequently, no hot carrier enhancement of the photorefractive effect was observed, and once formed, the Dember space-charge field decayed directly by ambipolar diffusion.
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Abdou, Rana, Mohamed alHor, Zubair Ahmed, and Noora Althani. "Development of organic–inorganic Halide Perovskites (OHPs) based Memristors." In Qatar University Annual Research Forum & Exhibition. Qatar University Press, 2021. http://dx.doi.org/10.29117/quarfe.2021.0017.
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Organic – inorganic halide perovskite (OHP) has drawn researchers’ attention working in the field of optoelectronics from last ten years due to its remarkable optical properties such as adjustable band gap, ambipolar charge transport, high optical absorption coefficients, and extended carrier diffusion lengths. OHP based memristors (memory + resistors) are a newly introduced passive two-terminal, nonlinear device used for information storage. In this work we have fabricated methyl ammonium lead iodide (MAPbI3) crystals-based device from MAPbI3 crystals. The crystals have been developed by simple solution process-based method. Developed crystals have shown highly porous geometry and trap charges across these pores facilitates higher conductivity. The fabricated device exhibits ~2.7 milli second response recovery time, which enabled elevated speed and showed hysteresis in the I-V characteristics thus demonstrating superior storage capacities. Hence, the developed device has been potential tool for next-generation non-volatile memories.
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Smirl, Arthur L., D. S. McCallum, A. N. Cartwright, X. R. Huang, Thomas F. Boggess, and T. C. Hasenberg. "Ultrafast Recovery of Hetero n-i-p-i's by Enhanced In-plane Diffusive Transport." In International Conference on Ultrafast Phenomena. Optica Publishing Group, 1992. http://dx.doi.org/10.1364/up.1992.thc19.
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Hetero n-i-p-i's are one of several semiconductor quantum-well devices that use second-order electro-optic effects and that continue to attract interest for possible applications to low-power two-dimensional switching arrays and all-optical spatial light modulators. The turn-on time for a hetero n-i-p-i device is usually determined by transport perpendicular to the quantum wells. More specifically, it is determined by the time required for carriers generated in the quantum wells to escape the wells and to move to screen the built-in electric field, thus shifting the exciton. Consequently, typical turn-on times are of the order of a few ps. By contrast, when used in the conventional single-beam geometry, the recovery (or turn-off) time of hetero n-i-p-i's is determined by the slow recombination of the spatially-separated charges in the doped regions and is typically in the range of µs-ms. If instead, however, we use a two-beam mixing geometry for the device (where gratings are written in the material by the interference of the two beams), then the decay or turn off of the signal is determined by the decay of the gratings by in-plane transport over micron dimensions. Here, we use transient grating techniques to measure the recovery of such photorefractive and photoabsorptive gratings written in all-binary hetero n-i-p-i's. In this geometry, we show that the separation of photo-generated charge actually speeds the recovery by enhancing the effective in-plane ambipolar diffusion coefficient by roughly an order of magnitude (in contrast to the single beam geometry where charge separation elongates the recombination and recovery time).
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Xue, S., P. Proulx, M. I. Boulos, and T. Murphy. "A Thermal and Chemical Non-Equilibrium Model for Multi-Component Ar-H2 Plasma." In ITSC2005, edited by E. Lugscheider. Verlag für Schweißen und verwandte Verfahren DVS-Verlag GmbH, 2005. http://dx.doi.org/10.31399/asm.cp.itsc2005p0305.
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Abstract A thermal and chemical non-equilibrium model is developed for the modelling of multi-component supersonic induction Ar-H2 plasma flows. The species included in the modelling are electrons(e), hydrogen ion(H+), hydrogen atoms(H), hydrogen molecules(H2), Argon ions(Ar+) and Argon atoms(Ar). The negative hydrogen ions(H-), molecular hydrogen ions(H2+) and second order ionisation are neglected. The chemical reactions considered in the modelling are the H2 dissociations and the corresponding recombination, induced by Ar atom and H2, and the ionisations of the hydrogen and Argon and the corresponding recombination. All the heavy species are assumed to have the same temperature (Ti). The electron temperature (Te) is allowed to deviate from that of heavy species. The energies for these chemical reactions have been treated as the source terms for energy conservation equations. As a result, the contributions of these chemical reactions to the total enthalpy are removed. Therefore, the heavy species temperature can be obtained by solving the thermal kinetic energy equation, rather than the total enthalpy equation. Yos’s mixing law is used to calculate the contribution of vibrational and rotational energies of hydrogen molecules to the thermal conductivity of heavy species. The transport properties are calculated using the formulas derived by Hirschfelder, Curtiss and Bird. The data of collision integrals or collision cross-sections between species in the mixture are taken from Murphy, Devoto and Mason’s publications. The binary mass diffusion coefficients between the species in the mixture are also calculated from these collision integral data. The mass diffusion of species in the mixture are modelled under the dilute approximation at present since the mole fraction of the principal species, Argon, in the whole computational region is more than 90%. For charged species, Ambipolar diffusion coefficients are used. Mass balance equations are solved to obtain the mass fractions or mole fractions or the number densities of all the species except for electrons. The electron number density is determined by the condition of electrical neutrality. The developed model is applied to the modelling of inductive plasma flow, generated by the Tekna PL-35 torch model, under different pressures and then to the supersonic plasma flow. The model has been validated by comparing the transport properties under the LTE conditions from this model with the corresponding published values.