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Author: Ying-quan Peng
Publisher:
ISBN: 9781604563696
Category : Charge transfer
Languages : en
Pages : 0
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Book Description
In this book we investigate mechanism of charge carrier transport in organic semiconductor thin film devices (OTFDs). Numerical models for the current conduction in single layer OTFDs including both injection and bulk effect for both trap free organics as well as organics with traps exponentially distributed in energy are developed. The dependencies of the current density on the operation voltage, the thickness of the organic layer and the trap properties are numerically studied.
Author: Ying-quan Peng
Publisher:
ISBN: 9781604563696
Category : Charge transfer
Languages : en
Pages : 0
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Book Description
In this book we investigate mechanism of charge carrier transport in organic semiconductor thin film devices (OTFDs). Numerical models for the current conduction in single layer OTFDs including both injection and bulk effect for both trap free organics as well as organics with traps exponentially distributed in energy are developed. The dependencies of the current density on the operation voltage, the thickness of the organic layer and the trap properties are numerically studied.
Author: Karl-Philipp Strunk
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Author: Zhenlin Rang
Publisher:
ISBN:
Category :
Languages : en
Pages : 218
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Book Description
Author: Georges Hadziioannou
Publisher: John Wiley & Sons
ISBN: 3527312714
Category : Technology & Engineering
Languages : en
Pages : 786
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Book Description
The field of semiconducting polymers has attracted many researchers from a diversity of disciplines. Printed circuitry, flexible electronics and displays are already migrating from laboratory successes to commercial applications, but even now fundamental knowledge is deficient concerning some of the basic phenomena that so markedly influence a device's usefulness and competitiveness. This two-volume handbook describes the various approaches to doped and undoped semiconducting polymers taken with the aim to provide vital understanding of how to control the properties of these fascinating organic materials. Prominent researchers from the fields of synthetic chemistry, physical chemistry, engineering, computational chemistry, theoretical physics, and applied physics cover all aspects from compounds to devices. Since the first edition was published in 2000, significant findings and successes have been achieved in the field, and especially handheld electronic gadgets have become billion-dollar markets that promise a fertile application ground for flexible, lighter and disposable alternatives to classic silicon circuitry. The second edition brings readers up-to-date on cutting edge research in this field.
Author: Victor I. Klimov
Publisher: CRC Press
ISBN: 1420079271
Category : Technology & Engineering
Languages : en
Pages : 485
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Book Description
A review of recent advancements in colloidal nanocrystals and quantum-confined nanostructures, Nanocrystal Quantum Dots is the second edition of Semiconductor and Metal Nanocrystals: Synthesis and Electronic and Optical Properties, originally published in 2003. This new title reflects the book’s altered focus on semiconductor nanocrystals. Gathering contributions from leading researchers, this book contains new chapters on carrier multiplication (generation of multiexcitons by single photons), doping of semiconductor nanocrystals, and applications of nanocrystals in biology. Other updates include: New insights regarding the underlying mechanisms supporting colloidal nanocrystal growth A revised general overview of multiexciton phenomena, including spectral and dynamical signatures of multiexcitons in transient absorption and photoluminescence Analysis of nanocrystal-specific features of multiexciton recombination A review of the status of new field of carrier multiplication Expanded coverage of theory, covering the regime of high-charge densities New results on quantum dots of lead chalcogenides, with a focus studies of carrier multiplication and the latest results regarding Schottky junction solar cells Presents useful examples to illustrate applications of nanocrystals in biological labeling, imaging, and diagnostics The book also includes a review of recent progress made in biological applications of colloidal nanocrystals, as well as a comparative analysis of the advantages and limitations of techniques for preparing biocompatible quantum dots. The authors summarize the latest developments in the synthesis and understanding of magnetically doped semiconductor nanocrystals, and they present a detailed discussion of issues related to the synthesis, magneto-optics, and photoluminescence of doped colloidal nanocrystals as well. A valuable addition to the pantheon of literature in the field of nanoscience, this book presents pioneering research from experts whose work has led to the numerous advances of the past several years.
Author: Beata Luszczynska
Publisher: John Wiley & Sons
ISBN: 3527814949
Category : Technology & Engineering
Languages : en
Pages : 688
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Book Description
Provides first-hand insights into advanced fabrication techniques for solution processable organic electronics materials and devices The field of printable organic electronics has emerged as a technology which plays a major role in materials science research and development. Printable organic electronics soon compete with, and for specific applications can even outpace, conventional semiconductor devices in terms of performance, cost, and versatility. Printing techniques allow for large-scale fabrication of organic electronic components and functional devices for use as wearable electronics, health-care sensors, Internet of Things, monitoring of environment pollution and many others, yet-to-be-conceived applications. The first part of Solution-Processable Components for Organic Electronic Devices covers the synthesis of: soluble conjugated polymers; solution-processable nanoparticles of inorganic semiconductors; high-k nanoparticles by means of controlled radical polymerization; advanced blending techniques yielding novel materials with extraordinary properties. The book also discusses photogeneration of charge carriers in nanostructured bulk heterojunctions and charge carrier transport in multicomponent materials such as composites and nanocomposites as well as photovoltaic devices modelling. The second part of the book is devoted to organic electronic devices, such as field effect transistors, light emitting diodes, photovoltaics, photodiodes and electronic memory devices which can be produced by solution-based methods, including printing and roll-to-roll manufacturing. The book provides in-depth knowledge for experienced researchers and for those entering the field. It comprises 12 chapters focused on: ? novel organic electronics components synthesis and solution-based processing techniques ? advanced analysis of mechanisms governing charge carrier generation and transport in organic semiconductors and devices ? fabrication techniques and characterization methods of organic electronic devices Providing coverage of the state of the art of organic electronics, Solution-Processable Components for Organic Electronic Devices is an excellent book for materials scientists, applied physicists, engineering scientists, and those working in the electronics industry.
Author: Zachary Alan Lamport
Publisher:
ISBN:
Category :
Languages : en
Pages : 120
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Book Description
The electrical properties of devices based on an organic compound result from the structure of the molecules, their solid-state packing, efficiency of charge injection from the electrodes, and the fabrication procedures. The length scales of interest can also vary widely, ranging from a few nanometers in the case of charge transport through single molecules or two-dimensional molecular ensembles, to tens of micrometers in devices focusing on thin films or molecular crystals. The work outlined in this thesis examines the characteristics of electronic devices at both extremes by incorporating organic molecules in molecular rectifiers and organic field-effect transistors (OFETs). We successfully designed and fabricated molecular rectifiers based on self-assembled monolayers and identified relevant structure-function relationships. We elucidate the dependence of the rectification behavior on molecular length and structure, and found that the degree of rectification is enhanced in shorter molecules and linearly dependent on the strength of the molecular dipole moment. We further developed compounds that, when included into the molecular diodes, rectified current by as much as three orders of magnitude depending on their structure. This performance is on par with that of the best molecular rectifiers obtained on a metallic electrode, but it has the advantage of lower cost and more efficient integration with current silicon technologies, which may yield hybrid systems that can expand the use of silicon towards novel functionalities governed by the molecular species grafted onto its surface. We then explored charge transport in OFETs using the organic semiconductor 7,14-bis(trimethylsilylethynyl)benzo[k]tetraphene (TMS-BT). We produced thin-film OFETs which exhibited more efficient electronic transport than single crystal devices of the same material, in spite of the inherent presence of grain boundaries. We explained these findings in terms of charge transport anisotropy and electronic trap formation at the interface between the semiconductor and dielectric. We further reduced aggressively the contact resistance in small molecule and polymer OFETs by varying the metal deposition rate, which resulted in over 5 times improved charge carrier mobility compared with the best reported devices with identical composition and structure. The obtained contact resistance normalized over the channel width was 500 Ωcm, and the corresponding devices exhibited charge carrier mobilities of 19.2 cm2/Vs for 2,8-difluoro-5,11-bis(triethylsilylethynyl) anthradithiophene (diF-TES ADT) and 10 cm2/Vs for indacenodithiophene-co-benzothiadiazole copolymer (C16IDTBT), with minimal dependence on the gate voltage.
Author: Sam Zhang
Publisher: CRC Press
ISBN: 1420093940
Category : Technology & Engineering
Languages : en
Pages : 256
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Book Description
Authored by leading experts from around the world, the three-volume Handbook of Nanostructured Thin Films and Coatings gives scientific researchers and product engineers a resource as dynamic and flexible as the field itself. The first two volumes cover the latest research and application of the mechanical and functional properties of thin films an
Author: Pyie Phyo Aung
Publisher:
ISBN:
Category : Charge transfer devices (Electronics)
Languages : en
Pages : 50
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Book Description
Thin film organic semiconductors have applications in electronic devices such as transistors, light emitting diodes, and organic solar cells. The performance of such devices depends on the mobility of the charge carriers which is strongly affected by the morphology of the material. In this work, we perform Monte Carlo simulations to study charge transport in lattice models of homogeneous and heterogeneous materials. The model device consists of a layer of the material between two electrodes at different potentials. Charge carriers are injected from the electrodes and move by hopping under the influence of the electric field and Coulomb interactions. To model the effect of polymer chain connectivity on charge transport we include an energetic barrier to hopping between sites on different chains. We measure current-voltage (I-V) characteristics of model devices and determine the mobility of the charge carriers from the slope of the I-V curves in the ohmic regime. We validate our algorithms with simulations of simple devices consisting of two parallel layers of donor and acceptor materials between the electrodes. To study the effect of ordered domains in polymeric semiconductors we simulate charge transport in a recently developed lattice model for polymers that undergo an order-disorder transition. We find that ordering in the material leads to strong anisotropies with increased mobility for transport parallel to the ordered domains and reduced mobility for perpendicular transport.
Author: Brandon Smith
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Organic semiconductors offer the potential for low cost, large area, and flexible electronic devices. However, the lower performance of organic materials relative to silicon, germanium, and other inorganic components has prevented widespread implementation. Correspondingly, the overarching goals of the work outlined in this dissertation focus on exploring the fundamental properties and intermolecular interactions of conjugated polymers and utilizing the findings to develop routes for improving thin-film transistor performance. Charge transport in organic active layers depends largely on the intrinsic carrier mobility of the semiconductor, the morphology achieved during processing and fabrication, as well as the effectiveness of the post-processing techniques. In this work, we investigate the influence of each and will show how appropriately tuning polymorphism, copolymerization between strong and weakly crystallizing moieties, and fluorine substitution on delocalized cores significantly enhance transistor characteristics. Crystalline organic molecules often exhibit the ability to assemble into multiple crystal structures depending on the processing conditions. Exploiting this polymorphism to optimize molecular orbital overlap between adjacent molecules in the unit lattice is a viable method for improving charge transport within the material. We have employed grazing-incident X-ray diffraction to demonstrate the formation of tighter stacking poly(3-hexylthiophene-2,5-diyl) polymorphs in films spin coated from ferrocene-containing solutions. As a result, the addition of ferrocene to casting solutions yields thin-film transistors which exhibit approximately three times higher source-drain currents and charge mobilities than neat polymer devices. Nevertheless, thorough analysis of the active layer reveals that all ferrocene is removed during the spin coating process, which may be an essential factor to achieve good mobilities. Such insights gleaned from ferrocene/poly(3-hexylthiophene) mixtures can serve as a template for selection and optimization of other small molecule/polymer systems with greater baseline charge mobilities. Block copolymerization provides yet another avenue for altering the crystal packing behavior and morphology of polymer semiconductors. Our work reveals that covalently coupling a weakly crystalline acceptor polymer with excellent electron mobility to a strongly crystallizing donor unit can induce ordering in the less crystalline block. Grazing-incidence X-ray scattering results confirm that shorter interchain spacing distances are obtained in poly(3-hexylthiophene)-b-poly(fluorene-dithiophene-benzothiadiazole) copolymers compared with neat poly(fluorene-dithiophene-benzothiadiazole) films. An enhancement in the ordering of the acceptor moiety was also observed both in neat homopolymer and copolymer samples after thermal annealing at 195 C. Consequently, the electron mobility of the block copolymer, measured in thin-film transistors with aluminum contacts, surpassed that of either homopolymer and peaked at annealing temperatures between 195 210 C. Several recent reports have surfaced in the literature in which fluorinated analogues of various donor/acceptor copolymers consistently surpass their non-fluorinated counterparts in terms of performance. Prior studies have speculated as to the origin of this fluorine effect, but concrete evidence has not been forthcoming. Using a benzodithiophene and benzotriazole copolymer series consisting of fluorinated, partially-fluorinated, and non-fluorinated analogues, we confirm that the addition of fluorine substituents beneficially impacts charge transport in polymer semiconductors. Transistor measurements demonstrated a 5x rise in carrier mobilities with the degree of fluorination of the backbone. Furthermore, X-ray diffraction data indicates progressively closer packing between the conjugated cores and an overall greater amount of crystallinity in the fluorinated materials. It is likely that attractive interactions between the electron-rich donor and fluorinated electron-deficient acceptor units induce very tightly stacking crystallites, which reduce the energetic barrier for charge hopping. In addition, a change in crystallite orientation was observed from primarily edge-on without fluorine substituents to mostly face-on with dual fluorine groups. We also introduce a promising post-processing technique adapted from existing zone purification and recrystallization methods. Zone annealing and zone refining are proposed for imparting directionality to the crystallization process, thereby increasing the size of crystallites and uninterrupted conjugation lengths within polymer films. A custom nichrome wire-based zone heating apparatus developed for zone refining thin films is described, and preliminary results with poly(3-hexylthiophene) are presented. A comparison with the UV-Vis absorbance of films annealed statically on a hot plate suggests that similar conjugation lengths can be achieved in approximately a sixth of the time with zone refining. Further optimization and investigatory studies are required before the procedure can be successfully extended to transistor samples, but zone crystallization appears to be a highly compatible post-processing approach for large scale manufacturing. The final portion of this work was dedicated to the development of potential integration venues for organic devices. Applications which take full advantage of the unique properties of polymer semiconductors will be needed as organic electronics begin the arduous transition into the commercial sphere. As such, neutron and X-ray detection systems represent two categories where very large area and flexibility would be invaluable. We therefore explore the feasibility of sensitizing conjugated materials towards either neutrons or X-rays through the incorporation of elements possessing excellent neutron capture or X-ray absorption properties. The projected mechanisms and challenges associated with direct radiation detection are discussed, and the results obtained from numerous screening experiments, conducted to determine which compounds maintain acceptable performance in transistors, are included. Based on these trials, boron nitride, 10B-enriched boric acid, and ruthenocene blended with poly(3-hexylthiophene) at extraordinarily high loadings were identified for further scrutiny and eventual response testing with an X-ray or neutron source. In summary, the objectives set forth for this work have been successfully realized. We examined the impact of several parameters governing charge transport in organic semiconductors, and based on our conclusions, we have identified three approaches for substantially augmenting the performance of polymer field-effect transistors. We have also considered a useful post-process treatment for large scale device fabrication and illustrated the benefits and potential for adapting conjugated materials for novel detection applications. The contributions of the research efforts expounded within this dissertation have far reaching implications yet represent only a small part of the general advance of the organic semiconductor field. Significant progress is being made on many critical fronts, and provided the allure of light weight, completely conformable electronics remains strong, we expect to continue witnessing the steady emergence of ever more numerous devices and gadgets based on organic transistors and diodes.
