The Influence Of Dilution On Structural And Optical Properties Of Organic Semiconductors

This monograph is concerned with the III-V bulk and low-dimensional semiconductors, with the emphasis on the implications of multi-valley bandstructures for the physical mechanisms essential for opto-electronic devices. The optical response of such semiconductor materials is determined by many-body effects such as screening, gap narrowing, Fermi-edge singularity, electron-hole plasma and liquid formation. Consequently, the discussion of these features reflects such interdependencies with the dynamics of excitons and carriers resulting from intervalley coupling.

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.

The continued development of organic semiconductor materials relies on an understanding of the relationship between optoelectronic properties, molecular structure, and molecular interaction. Several detailed studies of electronic properties in functionalized polyacene materials are presented. A computational model which allows the extraction of charge generation and transport properties from experimental data is developed. Ultrafast charge generation is observed, and the dependence of transient photocurrent data on this charge generation is determined. Greater crystallinitity of the donor leads to more efficient ultrafast charge generation, improving device performance. Voltage and incident intensity dependence data is fit using a single parameter set, allowing for the testing of multiple theoretical models against each other. The effect of acceptor addition to the donor material is investigated. Different acceptors allow for the isolation of effects due to packing and electronic structure interactions with the donor. New sources for organic materials to test are important to the future of the field. One novel source for organic small molecules is the secretions of wood-eating fungi. Optical and electronic characterisation is performed on xylindein, a fungally-derived molecule, as an example of the interesting properties and challenges which this source of material present.

Optical and electronic properties of semiconductors are strongly influenced by the different possibilities of carriers to be distributed among the various extrema of the band structure or the transfer between them. The monograph Optical Properties of III-V Semiconductors is concerned with the III-V bulk and low-dimensional semiconductors with the emphasis on the implications of multi-valley bandstructures on the physical mechanisms essential for opto-electronic devices. The optical response of such semiconductor materials is determined by many-body effects like screening, gap narrowing, Fermi-edge singularity, electron-hole plasma and liquid formation. The discussion of the latter features is presented self-consistently with the dynamics of excitons and carriers resulting from intervalley coupling.

Optical Properties and Band Structure of Semiconductors, Volume 1 presents the experimental studies of the fundamental energy band structure of semiconductors and insulators. This book provides detailed information of the available measurement methods and results for a large number of both cubic and non-cubic materials. Comprised of 10 chapters, this volume begins with an overview of the fundamental band structure of semiconductors. This text then discusses the instrumentation and methods available for the measurement of absorption coefficient, absolute reflection coefficient, and other optica ...

This thesis is dedicated to various aspects of liquid crystalline (LC) organic semiconductors (OSCs) in regard to their applications in the field of organic electronics. The first part of this work deals with a well-known LC OSC based on phenyl-naphtalene. Two major ways of performance improvement are proposed and investigated : stabilization of LC structure by in situ photo-polymerization and introduction of electron acceptor doping impurity. In the first case, the influence of polymer network on mesophase order and charge transport is investigated by conventional experimental techniques and Time-Of-Flight (TOF) mobility measurements. Fot the doped materials, ab initio calculations are employed to predict their spectroscopic properties which is exhaustively compared with the experimental data obtained by optical and vibrational spectroscopy. The charge transport is studied by TOF method in the mesophase, while crystalline phase is investigated via conductive atomic force microscopy. A prototype of organic field effect transistor (OFET) is prepared to obtain an estimate of performance for a relevant real-world application. The second part of this work includes design and synthesis of a novel LC semiconductor based on anthracene, additional attention is made to obtain an easy-to-make and low production cost material. Noval molecule is fully characterized : molecular structure is confirmed by relevant techniques ; frontier molecular energy levels are studied by optical spectroscopy and cyclic voltammetry and confronted to values obtaines via ab initio calculations ; mesophase properties are investigated by optical microscopy and scanning calorimetry. charge transporting properties are characterized by means of an OFET device : it is found that new anthracene-molecule exhibits significant improvement of field-effect hole mobility over previously studied phenyl naphtalene derivative. Finally, photoconductive properties of the novel material are addressed in order to investigate its potential applications to organic phototransistors.