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Author: Publisher: ISBN: Category : Languages : en Pages : 16
Book Description
The X-band spin 1 photoluminescence-detected magnetic resonance of frozen toluene solutions of poly (p-phenylene ethynylene) (PPE) and poly (p-phenylene)-type ladder (LPPP) polymers are presented. The amplitude of the 800-1100 G wide triplet resonance pattern decreases with decreasing concentration of PPE in toluene and tetrahydrofuran; in frozen saturated solutions of LPPP it is about half of that in neat films. The results suggest the resonance is largely due to a long-lived (^30 microsecs) trapped triplet exciton state localized on a phenylene ring and stabilized by coupling to a segment of an adjacent chain. The role of this trapped triplet in the photophysics of pi-conjugated polymers is discussed.
Author: Publisher: ISBN: Category : Languages : en Pages : 16
Book Description
The X-band spin 1 photoluminescence-detected magnetic resonance of frozen toluene solutions of poly (p-phenylene ethynylene) (PPE) and poly (p-phenylene)-type ladder (LPPP) polymers are presented. The amplitude of the 800-1100 G wide triplet resonance pattern decreases with decreasing concentration of PPE in toluene and tetrahydrofuran; in frozen saturated solutions of LPPP it is about half of that in neat films. The results suggest the resonance is largely due to a long-lived (^30 microsecs) trapped triplet exciton state localized on a phenylene ring and stabilized by coupling to a segment of an adjacent chain. The role of this trapped triplet in the photophysics of pi-conjugated polymers is discussed.
Author: Anna Köhler Publisher: John Wiley & Sons ISBN: 3527332928 Category : Technology & Engineering Languages : en Pages : 436
Book Description
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.
Author: Niyasi Serdar Sariciftci Publisher: World Scientific ISBN: 9814518212 Category : Science Languages : en Pages : 641
Book Description
This volume concentrates on the controversy within the scientific community over how to explain, understand and describe the photophysics/photochemistry of this class of materials.This controvery is of such a fundamental nature that the solution of the problem might be in a unification of the semiconductor and metal physics with the molecular quantum chemistry. Thus, a wide-ranging and comprehensive discussion of this very crucial issue has not been written down yet.This volume brings together the most prominent scientists specializing in this controversial topic. Each contributor addresses the opponents' arguments. After short introductory chapters, the contributors discuss their own speciality area and compare the results with both models and explain their position on why one of the models is more appropriate. Special emphasis is given to comparative discussions with other conjugated molecular systems as well as inorganic semiconductors.
Author: Chakraborty Rajarshi Publisher: ISBN: Category : Languages : en Pages : 129
Book Description
"Conjugated polymers are active candidates of research for their potential applications in organic electronic devices. This thesis contains experimental results of the photophysical behaviour of Poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) in the nanoseconds timescale. It is generally accepted that quantum yield of films are less than their solution counterparts and has a non-exponential "temporal tail" in the decay dynamics. This thesis reports the spectroscopy, excitation wavelength dependence, temperature dependence and electric field quenching of the temporal tail of the photoluminescence in MEH-PPV on a nanosecond timescale. We try to understand if a correlation exists between the "temporal tail" and quantum yield in films. We conclude that the tail represents emission from H-like aggregated regions in the polymer. Using a simple model of the photophysics, we estimate the formation yield of the aggregates responsible for the tail emission and conclude that they cannot account for the large reduction in fluorescence observed in densely packed films relative to that in solution. If recombination of injected charges in an OLED follows quantum spin statistics and all recombination forms the lowest excited states in a spin manifold, then the ratio of formed singlet to triplet exciton would be 1:3 setting an efficiency limit of 25% to the EL emission. However, in conjugated polymers, various studies have reported the formation ratio of singlet to triplet excitons to be greater than 1:3. These results have ambiguity due to issues of magnetoresistance, TTA, charge trapping, outcoupling etc. We try to reexamine the singlet-triplet branching ratio in Poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt- (benzo [2,1,3] thiadiazol-4,8-diyl) (F8BT) along with MEH-PPV with the hope of circumventing these problems. This approach involves simultaneous detection of singlet and triplet state luminescence and then estimate the recombination branching ratios directly from the change in singlet and triplet signals produced by applying magnetic fields. The role of PP in F8BT films are addressed based on studying the effect of external magnetic field on the DF and triplet signals of gold nanoparticle doped films. This work is unique and important because it includes a delay dependent magnetic field effect study of the DF suggesting that spin randomization of charge pairs is a fast process that occurs on the several hundred nanoseconds time scale. The magnetic field effect on the fluorescence persists to tens of microseconds and we argue that this apparent inconsistency implies the existence of an intermediate state in the recombination process that has implications for measurements and theoretical treatments of the singlet recombination fraction in electroluminescent conjugated polymers."--Pages ix-x.
Author: William Barford Publisher: Oxford University Press ISBN: 0198526806 Category : Language Arts & Disciplines Languages : en Pages : 280
Book Description
This book describes and explains the electronic and optical properties of conjugated polymers by developing theoretical models to understand the key electronic states.
Author: Srabanti Ghosh Publisher: John Wiley & Sons ISBN: 3527345574 Category : Technology & Engineering Languages : en Pages : 38
Book Description
A timely overview of fundamental and advanced topics of conjugated polymer nanostructures Conjugated Polymer Nanostructures for Energy Conversion and Storage Applications is a comprehensive reference on conjugated polymers for energy applications. Distinguished academic and editor Srabanti Ghosh offers readers a broad overview of the synthesis, characterization, and energy-related applications of nanostructures based on conjugated polymers. The book includes novel approaches and presents an interdisciplinary perspective rooted in the interfacing of polymer and synthetic chemistry, materials science, organic chemistry, and analytical chemistry. This book provides complete descriptions of conjugated polymer nanostructures and polymer-based hybrid materials for energy conversion, water splitting, and the degradation of organic pollutants. Photovoltaics, solar cells, and energy storage devices such as supercapacitors, lithium ion battery electrodes, and their associated technologies are discussed, as well. Conjugated Polymer Nanostructures for Energy Conversion and Storage Applications covers both the fundamental topics and the most recent advances in this rapidly developing area, including: The design and characterization of conjugated polymer nanostructures, including the template-free and chemical synthesis of polymer nanostructures Conjugated polymer nanostructures for solar energy conversion and environmental protection, including the use of conjugated polymer-based nanocomposites as photocatalysts Conjugated polymer nanostructures for energy storage, including the use of nanocomposites as electrode materials The presentation of different and novel methods of utilizing conjugated polymer nanostructures for energy applications Perfect for materials scientists, polymer chemists, and physical chemists, Conjugated Polymer Nanostructures for Energy Conversion and Storage Applications also belongs on the bookshelves of organic chemists and any other practicing researchers, academics, or professionals whose work touches on these highly versatile and useful structures.
Author: Jishan Wu Publisher: CRC Press ISBN: 1000565254 Category : Science Languages : en Pages : 638
Book Description
π-Conjugated molecules with an even number of π-electrons usually have a closed-shell ground state. However, recent studies have demonstrated that a certain type of molecules could show open-shell singlet ground state and display diradical-like (diradicaloid) behavior. Their electronic structure can be understood in terms of the “diradical character” and “aromaticity” concepts. They display very different electronic properties from traditional closed-shell π-conjugated molecules and could be used as next-generation molecular materials. This book provides a comprehensive review on the chemistry, physics, and material applications of open-shell singlet diradicaloids. Particularly, it elaborates the fundamental structure–diradical character–electronic property relationships both theoretically and experimentally. The book has been written by leading scientists in the field from Japan, Germany, Spain, Italy, China, and Singapore.
Author: R. Rigler Publisher: Springer Science & Business Media ISBN: 3642565441 Category : Science Languages : en Pages : 375
Book Description
The topics range from single molecule experiments in quantum optics and solid-state physics to analogous investigations in physical chemistry and biophysics.
Author: 
Author: 
Author: Lekshmi Sudha Devi
Author: Anna Köhler
Author: Niyasi Serdar Sariciftci
Author: Chakraborty Rajarshi
Author: William Barford
Author: Srabanti Ghosh
Author: 
Author: Jishan Wu
Author: R. Rigler