Microscopic View of Charge Injection in a Model Organic Semiconductor
Author: William Richard Silveira
Publisher:
Published: 2005
Total Pages: 630
ISBN-13:
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Author: William Richard Silveira
Publisher:
Published: 2005
Total Pages: 630
ISBN-13:
DOWNLOAD EBOOKAuthor: Kanokkorn Pimcharoen
Publisher:
Published: 2018
Total Pages: 207
ISBN-13: 9780438752245
DOWNLOAD EBOOKCharge injection and transport in organic semiconductors are key factors controlling the device performance, and have been intensively investigated by conductive atomic force microscope (c-AFM) experiments in the space-charge-limited current (SCLC) regime. The simplified SCLC theory, despite being widely used to describe the unipolar SCLC, has limitations in explaining the current-voltage responses of c-AFM measurements due to two major reasons. First, the conventional planar model does not include the effect of current spreading commonly found beneath the conducting tip. Secondly, the theory only considers drift transport, and assumes that charge diffusion can be neglected, causing discrepancies in its predictions of transport behaviors that will be discussed thoroughly here. The focus of this thesis is on developing numerical models for hole-only devices with the full description of drift and diffusion transport mechanisms, which is called the drift-diffusion (DD-) SCLC model. The applications of the models in the analysis of c-AFM experimental data are presented. We generalize the theory which takes both drift and diffusion currents into account, leading to more realistic DD-SCLC models for several applications. We then develop numerical approaches that efficiently simulate the hole-only SCLCs for one-, two-, and three- dimensional systems. In the case of fully 3-D calculations, the DD-SCLC model is able to treat inhomogeneous systems including spatially varying trap distributions, nanoscale morphologies, and the tip-plane (c-AFM) geometry. In the theoretical studies, the device simulations elucidate a number of crucial factors that affect the charge transport in the SCLC regime, including charge diffusion, traps, as well as, nanoscale morphology. We introduce the methodology of characterizing the current-voltage responses from c-AFM measurements, which has been used in elucidating the experiments on semiconductor poly(3-hexylthiophene) (P3HT) thin films that develop fibrous morphologies after thermal annealing. We generalize the theory which takes both drift and diffusion currents into account, leading to more realistic DD-SCLC models for several applications. We then develop numerical approaches that efficiently simulate the hole-only SCLCs for one-, two-, and three- dimensional systems. In the case of fully 3-D calculations, the DD-SCLC model is able to treat inhomogeneous systems including spatially varying trap distributions, nanoscale morphologies, and the tip-plane (c-AFM) geometry. In the theoretical studies, the device simulations elucidate a number of crucial factors that affect the charge transport in the SCLC regime, including charge diffusion, traps, as well as, nanoscale morphology. We introduce the methodology of characterizing the current-voltage responses from c-AFM measurements, which has been used in elucidating the experiments on semiconductor poly(3-hexylthiophene) (P3HT) thin films that develop fibrous morphologies after thermal annealing.
Author: Pascal Kordt
Publisher: Walter de Gruyter GmbH & Co KG
Published: 2016-09-12
Total Pages: 202
ISBN-13: 3110473631
DOWNLOAD EBOOKIn the field of organic semiconductors researchers and manufacturers are faced with a wide range of potential molecules. This work presents concepts for simulation-based predictions of material characteristics starting from chemical stuctures. The focus lies on charge transport – be it in microscopic models of amorphous morphologies, lattice models or large-scale device models. An extensive introductory review, which also includes experimental techniques, makes this work interesting for a broad readership. Contents: Organic Semiconductor Devices Experimental Techniques Charge Dynamics at Dierent Scales Computational Methods Energetics and Dispersive Transport Correlated Energetic Landscapes Microscopic, Stochastic and Device Simulations Parametrization of Lattice Models Drift–Diusion with Microscopic Link
Author: Yulong Shen
Publisher:
Published: 2004
Total Pages: 262
ISBN-13:
DOWNLOAD EBOOKAuthor: Louisa Marion Smieska
Publisher:
Published: 2015
Total Pages: 230
ISBN-13:
DOWNLOAD EBOOKOrganic semiconductors could have wide-ranging applications in lightweight, efficient electronic circuits. However, several fundamental questions regarding organic electronic device behavior have not yet been fully addressed, including the nature of chemical charge traps, and robust models for injection and transport. Many studies focus on engineering devices through bulk transport measurements, but it is not always possible to infer the microscopic behavior leading to the observed measurements. In this thesis, we present scanning-probe microscope studies of organic semiconductor devices in an effort to connect local properties with local device behavior. First, we study the chemistry of charge trapping in pentacene transistors. Working devices are doped with known pentacene impurities and the extent of charge trap formation is mapped across the transistor channel. Trap-clearing spectroscopy is employed to measure an excitation of the pentacene charge trap species, enabling identification of the degradationrelated chemical trap in pentacene. Second, we examine transport and trapping in peryelene diimide (PDI) transistors. Local mobilities are extracted from surface potential profiles across a transistor channel, and charge injection kinetics are found to be highly sensitive to electrode cleanliness. Trap-clearing spectra generally resemble PDI absorption spectra, but one derivative yields evidence indicating variation in trap-clearing mechanisms for different surface chemistries. Trap formation rates are measured and found to be independent of surface chemistry, contradicting a proposed silanol trapping mechanism. Finally, we develop a variation of scanning Kelvin probe microscopy that enables measurement of electric fields through a position modulation. This method avoids taking a numeric derivative of potential, which can introduce high-frequency noise into the electric field signal. Preliminary data is presented, and the theoretical basis for electric field noise in both methods is examined.
Author: Michael Kiy
Publisher:
Published: 2002
Total Pages: 110
ISBN-13:
DOWNLOAD EBOOKAuthor: Wolfgang Brütting
Publisher: John Wiley & Sons
Published: 2012-10-02
Total Pages: 660
ISBN-13: 3527654968
DOWNLOAD EBOOKThe field of organic electronics has seen a steady growth over the last 15 years. At the same time, our scientific understanding of how to achieve optimum device performance has grown, and this book gives an overview of our present-day knowledge of the physics behind organic semiconductor devices. Based on the very successful first edition, the editors have invited top scientists from the US, Japan, and Europe to include the developments from recent years, covering such fundamental issues as: - growth and characterization of thin films of organic semiconductors, - charge transport and photophysical properties of the materials as well as their electronic structure at interfaces, and - analysis and modeling of devices like organic light-emitting diodes or organic lasers. The result is an overview of the field for both readers with basic knowledge and for an application-oriented audience. It thus bridges the gap between textbook knowledge largely based on crystalline molecular solids and those books focusing more on device applications.
Author: Teunis van Woudenbergh
Publisher:
Published: 2005
Total Pages:
ISBN-13: 9789036722780
DOWNLOAD EBOOKAuthor: Sergei Baranovski
Publisher: John Wiley & Sons
Published: 2006-08-14
Total Pages: 498
ISBN-13: 0470095059
DOWNLOAD EBOOKThe field of charge conduction in disordered materials is a rapidly evolving area owing to current and potential applications of these materials in various electronic devices This text aims to cover conduction in disordered solids from fundamental physical principles and theories, through practical material development with an emphasis on applications in all areas of electronic materials. International group of contributors Presents basic physical concepts developed in this field in recent years in a uniform manner Brings up-to-date, in a one-stop source, a key evolving area in the field of electronic materials
Author: Gregor Meller
Publisher: Springer
Published: 2009-12-23
Total Pages: 338
ISBN-13: 3642045383
DOWNLOAD EBOOKDear Readers, Since the ground-breaking, Nobel-prize crowned work of Heeger, MacDiarmid, and Shirakawa on molecularly doped polymers and polymers with an alternating bonding structure at the end of the 1970s, the academic and industrial research on hydrocarbon-based semiconducting materials and devices has made encouraging progress. The strengths of semiconducting polymers are currently mainly unfolding in cheap and easily assembled thin ?lm transistors, light emitting diodes, and organic solar cells. The use of so-called “plastic chips” ranges from lightweight, portable devices over large-area applications to gadgets demanding a degree of mechanical ?exibility, which would overstress conventionaldevices based on inorganic,perfect crystals. The ?eld of organic electronics has evolved quite dynamically during the last few years; thus consumer electronics based on molecular semiconductors has gained suf?cient market attractiveness to be launched by the major manufacturers in the recent past. Nonetheless, the numerous challenges related to organic device physics and the physics of ordered and disordered molecular solids are still the subjects of a cont- uing lively debate. The future of organic microelectronics will unavoidably lead to new devi- physical insights and hence to novel compounds and device architectures of - hanced complexity. Thus, the early evolution of predictive models and precise, computationally effective simulation tools for computer-aided analysis and design of promising device prototypes will be of crucial importance.