The Doping Effect In Organic Semiconductor Anthracene

Shown this study the absorption and fluorescence spectra for organic semiconductor dissolved in a polar solvent. Used a diluted concentration to the purpose of minimizing the phenomenon of self-absorption. The measurements of these solutions spectra showed the electron exchange, which led to the energy transfer from the guest to the organic semiconductor. And shown the presence of energies activation organic semiconductor doping different proportions of 2-Methylnaphthallene; each activation energy has different mechanical connecting which could be interpreted by relying on the bands theory of semiconductor which proposes a transition charge which carriers from the fermi donor to the conduction band in the semiconductor negative (n-type)at high temperatures by thermal excitation. The X-ray diffraction spectra possess one sharp and two small peaks. It means that the film is polycrystalline in nature structure.

Thermoelectric materials can turn temperature differences directly into electricity. To use this to harvest e.g. waste heat with an efficiency that approaches the Carnot efficiency requires a figure of merit ZT larger than 1. Compared with their inorganic counterparts, organic thermoelectrics (OTE) have numerous advantages, such as low cost, large-area compatibility, flexibility, material abundance and an inherently low thermal conductivity. Therefore, organic thermoelectrics are considered by many to be a promising candidate material system to be used in lower cost and higher efficiency thermoelectric energy conversion, despite record ZT values for OTE currently lying around 0.25. A complete organic thermoelectric generator (TEG) normally needs both p-type and n-type materials to form its electric circuit. Molecular doping is an effective way to achieve p- and ntype materials using different dopants, and it is necessary to fundamentally understand the doping mechanism. We developed a simple yet quantitative analytical model and compare it with numerical kinetic Monte Carlo simulations to reveal the nature of the doping effect. The results show the formation of a deep tail in the Gaussian density of states (DOS) resulting from the Coulomb potentials of ionized dopants. It is this deep trap tail that negatively influences the charge carrier mobility with increasing doping concentration. The trends in mobilities and conductivities observed from experiments are in good agreement with the modeling results, for a large range of materials and doping concentrations. Having a high power factor PF is necessary for efficient TEG. We demonstrate that the doping method can heavily impact the thermoelectric properties of OTE. In comparison to conventional bulk doping, sequential doping can achieve higher conductivity by preserving the morphology, such that the power factor can improve over 100 times. To achieve TEG with high output power, not only a high PF is needed, but also having a significant active layer thickness is very important. We demonstrate a simple way to fabricate multi-layer devices by sequential doping without significantly sacrificing PF. In addition to the application discussed above, harvesting large amounts of heat at maximum efficiency, organic thermoelectrics may also find use in low-power applications like autonomous sensors where voltage is more important than power. A large output voltage requires a high Seebeck coefficient. We demonstrate that density of states (DOS) engineering is an effective tool to increase the Seebeck coefficient by tailoring the positions of the Fermi energy and the transport energy in n- and p-type doped blends of conjugated polymers and small molecules. In general, morphology heavily impacts the performance of organic electronic devices based on mixtures of two (or more) materials, and organic thermoelectrics are no exception. We experimentally find that the charge and energy transport is distinctly different in well-mixed and phase separated morphologies, which we interpreted in terms of a variable range hopping model. The experimentally observed trends in conductivity and Seebeck coefficient are reproduced by kinetic Monte Carlo simulations in which the morphology is accounted for.

The first advanced textbook to provide a useful introduction in a brief, coherent and comprehensive way, with a focus on the fundamentals. After having read this book, students will be prepared to understand any of the many multi-authored books available in this field that discuss a particular aspect in more detail, and should also benefit from any of the textbooks in photochemistry or spectroscopy that concentrate on a particular mechanism. Based on a successful and well-proven lecture course given by one of the authors for many years, the book is clearly structured into four sections: electronic structure of organic semiconductors, charged and excited states in organic semiconductors, electronic and optical properties of organic semiconductors, and fundamentals of organic semiconductor devices.

One branch of modern electronics requires avoiding the high processing costs associated with inorganic semiconductors in order to create novel low-cost, mechanically flexible, and low-profile devices for the next generation of consumer devices. Organic semiconductors can be doped to improve their charge mobility and carrier density towards creating better polymer-based photovoltaics, organic thin-film transistors, and organic light-emitting diodes. Dopants offer one route to improved device performance, but the specific interactions between the dopant molecule and the semiconductor must be designed for the desired function.This work explores the effects of sulfonic acid groups on the behavior of the common organic semiconductor poly-(3-hexylthiophene) (P3HT). P3HT was chosen for its ubiquitous use in photovoltaics and other organic electronic applications. The doping of P3HT by sulfonic acid-containing moieties was explored initially as a method to replace the poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) electron blocking later at the photovoltaic transparent indium tin oxide electrode. Measurements of doped thiophene-based polymers were conducted in organic thin-film transistor geometries to measure the charge carrier densities. Additionally, spectroscopic evidence of doping complemented the transistor and photovoltaic studies. This work explores the extent to which P3HT can be doped at the highest density and how it may be used in modern organic electronics such as transistors, photovoltaics, and light-emitting diodes.

The 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.

Organic electronics is a promising route for the next generation of electronic devices. With large area scalability, compatibility with flexible and semitransparent substrates, and low temperature processability, printed electronics offers an interesting alternative to conventional silicon-based electronics. On its way to achieve better performances, hole and electron doping needs to be developed to improve the material conductivity as well as the polymer-metal electrode contact. In this work, we have studied the electrical characteristics of the polymer PBDTTT-c upon addition of p-dopant Mo(tfd-COCF3)3. Complementary electrical (variable temperature current voltage, capacitance, admittance spectroscopy), optical (UV-visible absorption and photoluminescence spectroscopy) and material (NMR, SEM, TEM) characterization techniques have been used to analyze the impact of the doping concentration on the electrical properties of the polymer and improve our understanding of the doping mechanism involved. The doped layer was then successfully integrated in an organic photodetector using soft contact transfer lamination to replace the widely used PEDOT:PSS layer, known to be responsible for stability issues. Finally, both the lamination technique and the knowledge acquired on organic semiconductor doping were used to study the impact of unintentional oxygen doping on the organic photodetector performances.Although further works are necessary to complete our understanding of organic semiconductor doping, enhance the lamination processes and introduce doped layers in various solution printed devices, present results are promising for the improvement of organic electronic devices.

Televisions, telephones, watches, calculators, robots, airplanes and space vehicles all depend on silicon chips. Life as we know it would hardly be possible without semiconductor devices. An understanding of how these devices work requires a detailed knowledge of the physics of semiconductors, including charge transport and the emission and absorption of electromagnetic waves. This book may serve both as a university textbook and as a reference for research and microelectronics engineering. Each section of the book begins with a description of an experiment. The theory is then developed as far as necessary to understand the experimental results. Everyone with high-school mathematics should be able to follow the calculations. The band structure calculations for the diamond and zinc blende types of lattice are supplemented with a personal computer program. Semiconductor physics developed most rapidly in the two decades following the invention of the transistor, and naturally most of the references date from this time. But recent developments such as the Gunn effect, the acoustoelectric effect, superlattices, quantum well structures, and the quantum Hall effect are also discussed. The exercises provided (answers to which are available) will greatly assist the student in consolidating the material presented. From the reviews:"This book is a must for any theoretical and experimental physicist working in the area of semiconductor physics." #Physicalia#1