Download or read book Transport Properties of Molecular Junctions written by Natalya A. Zimbovskaya and published by Springer. This book was released on 2013-09-07 with total page 338 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive overview of the physical mechanisms that control electron transport and the characteristics of metal-molecule-metal (MMM) junctions. As far as possible, methods and formalisms presented elsewhere to analyze electron transport through molecules are avoided. This title introduces basic concepts--a description of the electron transport through molecular junctions—and briefly describes relevant experimental methods. Theoretical methods commonly used to analyze the electron transport through molecules are presented. Various effects that manifest in the electron transport through MMMs, as well as the basics of density-functional theory and its applications to electronic structure calculations in molecules are presented. Nanoelectronic applications of molecular junctions and similar systems are discussed as well. Molecular electronics is a diverse and rapidly growing field. Transport Properties of Molecular Junctions presents an up-to-date survey of the field suitable for researchers and professionals.

Download or read book Transport Properties of Molecular Junctions written by Natalya A. Zimbovskaya and published by Springer. This book was released on 2013-09-07 with total page 350 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive overview of the physical mechanisms that control electron transport and the characteristics of metal-molecule-metal (MMM) junctions. As far as possible, methods and formalisms presented elsewhere to analyze electron transport through molecules are avoided. This title introduces basic concepts--a description of the electron transport through molecular junctions—and briefly describes relevant experimental methods. Theoretical methods commonly used to analyze the electron transport through molecules are presented. Various effects that manifest in the electron transport through MMMs, as well as the basics of density-functional theory and its applications to electronic structure calculations in molecules are presented. Nanoelectronic applications of molecular junctions and similar systems are discussed as well. Molecular electronics is a diverse and rapidly growing field. Transport Properties of Molecular Junctions presents an up-to-date survey of the field suitable for researchers and professionals.

Download or read book Electronic and Transport Properties of Molecular and Semiconductor Junctions from First principles written by 呂台華 and published by . This book was released on 2010 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nanoscale Interface for Organic Electronics written by Mitsumasa Iwamoto and published by World Scientific. This book was released on 2011 with total page 387 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book treats the important issues of interface control in organic devices in a wide range of applications that cover from electronics, displays, and sensors to biorelated devices. This book is composed of three parts: Part 1, Nanoscale interface; Part 2, Molecular electronics; Part 3, Polymer electronics.

Download or read book Stretching effect on the spin transport properties of single molecular junctions written by 唐毓慧 and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Charge Transport in Molecular Junctions written by Michele Kotiuga and published by . This book was released on 2015 with total page 195 pages. Available in PDF, EPUB and Kindle. Book excerpt: Here, we use and develop first-principles methods based on density functional theory (DFT) and beyond to understand and predict charge transport phenomena in the novel class of nanostructured devices: molecular junctions. Molecular junctions, individual molecules contacted to two metallic leads, which can be systematically altered by modifying the chemistry of each component, serve as test beds for the study of transport at the nanoscale. To date, various experimental methods have been designed to reliably assemble and mea- sure transport properties of molecular junctions. Furthermore, theoretical methods built on DFT designed to yield quantitative agreement with these experiments for certain classes of molecular junctions have been developed. In order to gain insight into a broader range of molecular junctions and environmental effects associated with the surrounding solution, this dissertation will employ, explore and extend first-principles DFT calculations coupled with approximate self-energy corrections known to yield quantitative agreement with experiments for certain classes of molecular junctions. To start we examine molecular junctions in which the molecule is strongly hybridized with the leads: a challenging limit for the existing methodology. Using a physically motivated tight-binding model, we find that the experimental trends observed for such molecules can be explained by the presence of a so-called "gateway" state associated with the chemical bond that bridges the molecule and the lead. We discuss the ingredients of a self-energy corrected DFT based approach to quantitatively predict conductance in the presence of these hybridization effects. We also develop and apply an approach to account for the surrounding environment on the conductance, which has been predominantly ignored in past transport calculations due to computational complexity. Many experiments are performed in a solution of non-conducting molecules; far from benign, this solution is known to impact the measured conductance by as much as a factor of two. Here, we show that the dominant effect of the solution stems from nearby molecules binding to the lead surface surrounding the junction and altering the local electrostatics. This effect operates in much the same way adsorbates alter the work function of a surface. We develop a framework which implicitly includes the surrounding molecules through an electrostatic-based lattice model with parameters from DFT calculations, reducing the computational complexity of this problem while retaining predictive power. Our approach for computing environmental effects on charge transport in such junctions will pave the way for a better understanding of the physics of nanoscale devices, which are known to be highly sensitive to their surroundings.

Download or read book Design and Control of Highly Conductive Single Molecule Junctions written by Satoshi Kaneko and published by Springer. This book was released on 2017-04-04 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes improvements to and control of the electrical conductance in single-molecule junctions (SMJs), which have potential applications in molecular electronics, with a focus on the bonding between the metal and molecule. In order to improve the electrical conductance, the π orbital of the molecule is directly bonded to the metal orbital, because anchoring groups, which were typically used in other studies to bind molecule with metal electrodes, became resistive spacers. Using this direct π-binding, the author has successfully demonstrated highly conductive SMJs involving benzene, endohedral metallofullerene Ce@C82, and nitrogen. Subsequently, the author investigated control of the electrical conductance of SMJs using pyrazine. The nitrogen atom in the π-conjugated system of pyrazine was expected to function as an anchoring point, and two bonding states were expected. One originates primarily from the π orbital, while the other originates primarily from an n state of the nitrogen. Measurements of conductance and dI/dV spectra coupled with theoretical calculations revealed that the pyrazine SMJ has bistable conductance states, in which the pyrazine axis is either tilted or parallel with respect to the junction axis. The bistable states were switched by changing the gap size between the metal electrodes using an external force. Notably, it is difficult to change the electrical properties of bulk-state materials using mechanical force. The findings reveal that the electron transport properties of a SMJ can be controlled by designing a proper metal–molecule interface, which has considerable potential for molecular electronics. Moreover, this thesis will serve as a guideline for every step of SMJ research: design, fabrication, evaluation, and control.

Download or read book Inelastic Transport In Molecular Junctions from First Principles written by Sejoong Kim (Ph. D.) and published by . This book was released on 2012 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work is dedicated to development of a first-principle approach to study electron-vibration interactions on quantum transport properties. In the first part we discuss a general implementation for inelastic transport calculations based on maximally localized Wannier functions and non-equilibrium Green's functions. Our approach is designed to determine inelastic transport properties such as differential conductances, inelastic tunneling spectroscopies and nonequilibrium vibrational populations. Our approach is first applied to benzene molecular junctions connected to cumulene and carbon nanotube electrodes. In these examples, we discuss the role of the multichannel effect and of parity selection rules on the polarity of conductance steps, and the appearance of a non-monotonic behavior in the vibrational population. In the second part, we extend our formalism to study the effect of the electron-vibration interactions on the local current distribution. Using non-equilibrium Green's functions, we derive an expression for the local distribution of the inelastic current. Applying this to the benzene-cumulene junction, we show that the electron-vibration interaction can lead to a locally inverted current direction and the formation of loop currents. In the third part, we present a comprehensive study of the elastic and inelastic transport properties of carbon nanotube-zigzag graphene nanoribbon junctions, as realized in recent experiments, focusing on the local current distribution over the junctions. We calculate the local distribution of the elastic current to visualize the current injection pattern from the CNT electrodes to the ZGNRs and the current path inside the ZGNRs. For inelastic transport properties, we find a similarity in the IETS peaks and the corresponding vibrational configurations for the CNT/ZGNR/CNT junctions with different widths. As observed in the benzene-cumulene junction, we find that the inelastic current emerges from a complex network that includes loop currents. Our method and implementation can be generalized to other types of interactions, and is not limited to the electron-vibration interactions. Thus our work will be a starting point to understand the role of different and diverse interaction effects on quantum transport, using realistic predictive first-principle calculations.

Download or read book Molecular Junction of Transport Properties and Seebeck Coefficients Calculations written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Introduction to Mesoscopic Physics written by Yoseph Imry and published by . This book was released on 2002 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mesoscopic physics refers to the physics of structures larger than a nanometer (one billionth of a meter) but smaller than a micrometer (one millionth of a meter). This size range is the stage on which the exciting new research on submicroscopic and electronic and mechanical devices is being done. This research often crosses the boundary between physics and engineering, since engineering such tiny electronic components requires a firm grasp of quantum physics. Applications for the future may include such wonders as microscopic robot surgeons that travel through the blood stream to repair clogged arteries, submicroscopic actuators and builders, and supercomputers that fit on the head of a pin. The world of the future is being planned and built by physicists, engineers, and chemists working in the microscopic realm. This book can be used as the main text in a course on mesoscopic physics or as a supplementary text in electronic devices, semiconductor devices, and condensed matter physics courses. For this new edition, the author has substantially updated and modified the material especially of chapters 3: Dephasing, 8: Noise in mesoscopic systems, and the concluding chapter 9.

Download or read book Probing Electronic and Thermoelectric Properties of Single Molecule Junctions written by Jonathan R. Widawsky and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We also report the thermopower of the highly conducting, covalently bound molecular junctions that we have recently been able to form, and learn that, because of their unique transport properties, the junction power factors, GS2, are extremely high. Finally, we discuss the measurement of molecular current-voltage curves and consider the electronic and physical effects of applying a large bias to the system. We conclude with a summary of the work discussed and an outlook on related scientific studies.

Download or read book First Principles Investigations of Electronic Structure and Transport Properties of Graphitic Structures and Single Molecular Junctions written by Jonathan R. Owens and published by . This book was released on 2014 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Application of Quantum Mechanics in Reactivity of Molecules written by Sérgio F. Sousa and published by MDPI. This book was released on 2021-03-19 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over recent decades, the increase in computational resources, coupled with the popularity of competitive quantum mechanics alternatives (particularly DFT), has promoted the widespread penetration of quantum mechanics calculations into a variety of fields targeting the reactivity of molecules. This book presents a selection of original research papers and review articles illustrating diverse applications of quantum mechanics in the study of problems involving molecules and their reactivity.

Download or read book Nanogap Electrodes written by Tao Li and published by John Wiley & Sons. This book was released on 2021-07-14 with total page 432 pages. Available in PDF, EPUB and Kindle. Book excerpt: Unique in its scope, this book comprehensively combines various synthesis strategies with applications for nanogap electrodes. Clearly divided into four parts, the monograph begins with an introduction to molecular electronics and electron transport in molecular junctions, before moving on to a whole section devoted to synthesis and characterization. The third part looks at applications with single molecules or self-assembled monolayers, and the whole is rounded off with a section on interesting phenomena observed using molecular-based devices.

Download or read book Approach to Control Protect and Switch Charge Transport Through Molecular Junctions and Atomic Contact written by Yong Ai and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Molecular electronics has attracted increasing interest in the past decades. Constructing metal/molecules/metal junctions is a basic step towards the investigation of molecular electronics. We have witnessed significant development in both experiment and theory in molecular junctions. This thesis focuses mainly on the study of charge transport through molecular junctions. Conducting polymers and copper filaments were electrochemically deposited with a scanning electrochemical microscope (SECM) configuration between a tip and a substrate electrode. In doing so, we have developed a new way to fabricate atomic contact and molecular junctions, and we have explored the possibility to control, protect and switch these systems.Firstly, SECM, where two microelectrodes are located face-to-face separated by a micrometric gap, has been successfully used for the fabrication of redox-gated conducting polymers junctions, such as PEDOT and PBT. Highly stable and reversible redox-gated nano-junctions were obtained with conductance in the 10-7-10-8 S range in their conducting states. These results, associated with the wire-like growth of the polymer, suggest that the conductance of the entire junction in the conductive state is governed by less than 20 to 100 oligomers.Secondly, to obtain the nano-junctions in a controllable way, a break junction strategy combined with the SECM set up is adopted. A nano-junction could be acquired by pulling the tip away from its initial position. And conductance traces showed that PEDOT junctions can be broken step by step before complete breakdown. Similarly as STM-BJ conductance steps were observed on a PEDOT molecular junction before break down by using SECM-BJ. SECM break junction technique proved to be an efficient way of molecular junction fabrication studies, especially for redox gated polymer molecular junctions. Moreover, a self-terminated strategy is found to be another way to obtain nano-junctions. An external resistance connected to the electrode plays an important role in controlling the size of conducting polymer junctions.PFTQ and PFETQ molecular junctions exhibit well-defined ambipolar transport properties. However, an unbalanced charge transport properties in n- and p- channel for these two polymer junctions was observed when the junctions are in the fiber device scale. In contrast, when molecular junction changes into nano-junction, a balanced n- and p-channel transport property is acquired. We propose that such effect is due to charge transport mechanism changing from diffusive (ohm's law) to ballistic (quantum theory) when the junction size is reduced from fiber devices to nanodevices.High stable Au NPs/ITO electrodes exhibit a well localized surface plasmon (LSP) behavior. These plasmonic substrates have been successfully used to trigger switching of molecular junctions under light irradiation, demonstrating that surface plasmon resonance can induce electrochemical reduction. Such conductance reduction can be attributed to the hot electrons plasmonically generated from gold nanoparticles trapped into the PEDOT junction, resulting in PEDOT being reduced and changed to an insulating state.Finally, copper metallic nanowires were generated using an electrochemical self-terminated method based on SECM configuration. The presence of a few atoms that control the electron transport highlights the formation of metallic nanowires between the asymmetric electrodes. Furthermore, a similar study was performed on mesoporous silica film on ITO used as a substrate electrode. The mesoporous silica films have vertically aligned channels with a diameter of about 3 nm and a thickness of 115 nm, which play a crucial role in protecting the copper filament.

Download or read book A Computational and Theoretical Study of Conductance in Hydrogen bonded Molecular Junctions written by Michael Wimmer and published by . This book was released on 2017 with total page 125 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis is devoted to the theoretical and computational study of electron transport in molecular junctions where one or more hydrogen bonds are involved in the process. While electron transport through covalent bonds has been extensively studied, in recent work the focus has been shifted towards hydrogen-bonded systems due to their ubiquitous presence in biological systems and their potential in forming nano- junctions between molecular electronic devices and biological systems. This analysis allows us to significantly expand our comprehension of the experimentally observed result that the inclusion of hydrogen bonding in a molecular junction significantly impacts its transport properties, a fact that has important implications for our understanding of transport through DNA, and nano-biological interfaces in general. In part of this work I have explored the implications of quasiresonant transport in short chains of weakly-bonded molecular junctions involving hydrogen bonds. I used theoretical and computational analysis to interpret recent experiments and explain the role of Fano resonances in the transmission properties of the junction.In a different direction, I have undertaken the study of the transversal conduction through nucleotide chains that involve a variable number of different hydrogen bonds, e.g. NH...O, OH...O, and NH...N, which are the three most prevalent hydrogen bonds in biological systems and organic electronics. My effort here has fo- cused on the analysis of electronic descriptors that allow a simplified conceptual and computational understanding of transport properties. Specifically, I have expanded our previous work where the molecular polarizability was used as a conductance de- scriptor to include the possibility of atomic and bond partitions of the molecular polarizability. This is important because it affords an alternative molecular descrip- tion of conductance that is not based on the conventional view of molecular orbitals as transport channels. My findings suggest that the hydrogen-bond networks are crucial in understanding the conductance of these junctions. A broader impact of this work pertains the fact that characterizing transport through hydrogen bonding networks may help in developing faster and cost-effective approaches to personalized medicine, to advance DNA sequencing and implantable electronics, and to progress in the design and application of new drugs.

Download or read book Charge carrier Transport Measurements Through Single Molecules written by Emanuel Marc Lörtscher and published by Cuvillier Verlag. This book was released on 2007 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: