Download or read book Investigation of the Photophysical Properties of conjugated pi conjugated Polymers written by Richard Hildner and published by . This book was released on 2008 with total page 137 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Investigation of the Photophysical Properties of Pi conjugated Polymers written by Richard Hildner and published by . This book was released on 2008 with total page 137 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Investigation of the Photophysical Properties of P conjugated pi conjugated Polymers written by Richard Hildner and published by . This book was released on 2008 with total page 137 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Investigation of the Photophysical Properties of Some Conjugated Polymers written by D. A. Ross and published by . This book was released on 1980 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis of Conjugated Polymers with Pendant Metal Complexes and Study of Their Photophysical Properties written by Ka-Wing Tsoi and published by Open Dissertation Press. This book was released on 2017-01-27 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Synthesis of Conjugated Polymers With Pendant Metal Complexes and Study of Their Photophysical Properties" by Ka-wing, Tsoi, 蔡家榮, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: A series of copolymers based on poly(phenylene thienylene) mainchain that contains pendent bisterpyridine ruthenium(II) complexes was synthesized by palladium catalyzed Suzuki coupling reaction. The polymers contain different proportion of metal complexes. The copolymers exhibit broad absorption band in the visible region due to the conjugated backbone and the bisterpyridine ruthenium complexes. The relative intensity of each absorption band depends on the metal complex contents. There is a significant spectral overlap between the emission of the conjugated polymer mainchain and the absorption of the ruthenium complexes. It was found that there is a quenching of polymer emission by the complexes. Based on the results obtained by spectroscopic studies, it is proposed to be Forster type energy transfer process between the polymer mainchain as the donor and the complexes as the acceptors. Two donor-acceptor molecules with pyrazinopyrazine bridge units were synthesized. They exhibit intramolecular charge transfer character and were characterized by 1 H NMR, FTIR, UV-visible absorption and mass spectrometry. The two compounds have absorption band in the near IR region and exhibit narrow band gap. Through structural modification, their optical and electronic properties can be fine tuned. They have potential applications in organic photovoltaic cells and organic field effect transistors. DOI: 10.5353/th_b5351043 Subjects: Conjugated polymers
Download or read book Photophysical Studies of Pi conjugated Oligomers and Polymers That Incorporate Inorganic MLCT Chromophores written by Keith Walters and published by . This book was released on 2019-05-31 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: The photophysics and photochemistry of several molecular series incorporating inorganic MLCT chromophores within pi-conjugated oligomers and polymers is presented, including photothermal measurements to determine nonradiative decay rates. Dissertation Discovery Company and University of Florida are dedicated to making scholarly works more discoverable and accessible throughout the world. This dissertation, "Photophysical Studies of Pi-conjugated Oligomers and Polymers That Incorporate Inorganic MLCT Chromophores" by Keith A. Walters, was obtained from University of Florida and is being sold with permission from the author. A digital copy of this work may also be found in the university's institutional repository, IR@UF. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation.
Download or read book Synthesis of Conjugated Polymers with Pendant Metal Complexes and Study of Their Photophysical Properties written by 蔡家榮 and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Investigation of Photophysical and Photochemical Processes in Conjugated Polymer Nanoparticles by Single Particle and Ensemble Spectroscopy written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Investigation of photophysical and photochemical processes in conjugated polymer nanoparticles by single particle and ensemble spectroscopy.
Download or read book Conjugated Polymers written by Terje A. Skotheim and published by CRC Press. This book was released on 2006-12-26 with total page 1030 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many significant fundamental concepts and practical applications have developed since the publication of the best-selling second edition of the Handbook of Conducting Polymers. Now divided into two books, the third edition continues to retain the excellent expertise of the editors and world-renowned contributors while providing superior coverage of
Download or read book Pyridine Based Conjugated Polymers Photophysical Properties and Light Emitting Diodes written by and published by . This book was released on 1997 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: We study the photophysical properties of the pyridine-based polymers poly (p-pyridyl vinylene) (PPyV) and poly (p-pyridine) (PPy). The primary photoexcitations in the pyridine-based polymers are singlet excitons. We observe direct intersystem crossing (ISC) on picosecond timescales with the volume density of triplet excitons varying with the sample morphology (film or powder). These effects are demonstrated clearly by examining the millisecond photoinduced absorption characteristics of powder and film forms of PPyV. The pyridine-based polymers have been shown to be promising candidates for polymer light-emitting devices both the 'conventional ' diode device and symmetrically configured ac light-emitting (SCALE) device. Here we examine the role of 'insulating' layers and their interfaces with the emitting layer and electrodes in the SCALE device operation with emphasis on the central role of the polymer-polymer interfaces.
Download or read book Photophysics of Conjugated Polymers written by Tieneke E. Dykstra and published by . This book was released on 2008 with total page 326 pages. Available in PDF, EPUB and Kindle. Book excerpt: Poly (para-phenylenevinylene) (PPV), and its derivatives such as poly [2-methoxy, 5-(2'-ethyl-hexoxy)-1,4-phenylene vinylene] (MEH-PPV), are typical conjugated polymers. In order to implement conjugated polymers into processable electronics technologies, we must first understand their complex photophysical properties as their efficiencies depend on the balance between exciton recombination and charge carrier formation. The inherent complexities of these materials arise from entanglement of the pi-electron system with disorder and nuclear motions of the polymer backbone. This disorder breaks the polymer chain into conformational subunits which can couple, giving rise to a set of delocalized states formed by Coulombic interactions between proximate subunits. Characteristics of PPVs include high quantum yields, non-mirror image absorption and fluorescence line shapes, and large apparent Stokes' shifts. These properties are discussed in the context of the relationships between polymer conformation, electronic structure, coupling, disorder and polymer photophysics.These important influences are often manifest in the dynamics of what happens after photoexcitation. In this work, we present 3-pulse photon echo peak shift (3PEPS) studies of conjugated polymers in both solution and film. To elucidate timescales characteristic of relaxation processes, we have simulated the 3PEPS data simultaneously with absorption and fluorescence, observing a rapid localization of the exciton in the initial ∼ 20 fs. Additional contributions to the decay of the peakshift are discussed. We also present transient anisotropy data for PPV polymers and oligomers which is compared to dynamics simulation for isolated chains of PPVs. This work demonstrates the influence of microscopic structure on ultrafast dynamics. We show that relaxation between exciton states can lead to rapid depolarization of the anisotropy, even though the spatial extent of exciton migration may be small. Generally, the connection between conformation and electronic structure is a theme throughout this thesis.
Download or read book Understanding the Correlation Between Microscopic Morphology and Photophysical Properties of Conjugated Polymers by Optical Spectroscopy written by Liwei Wang (Chemist) and published by . This book was released on 2021 with total page 139 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The unique photophysical and electronic properties of conjugated polymers (CPs) make them promising candidates for applications in displays, biosensors, field-effect transistors and photovoltaic devices. The photophysical properties of CPs are strongly dependent on the chain morphology. However, the understanding of the morphology-property correlation is still obscured both due to inhomogeneities in ensemble experiments and even due to multichromophoric properties in single chain experiments. In this dissertation, we constructed a single molecule spectroscopy apparatus and home-built MATLAB code together to correlate simultaneous measurements of intensity, lifetime and spectrum to learn more about proper photophysical models to describe the properties of CPs, the effect of O2, and the role of energy transfer in CPs. Bulk experiments in mixed solvents where chain conformations can be varied were also conducted to understand the CPs from a macroscopic perspective, where chain-chain interactions also play an important role. Especially, we selected three CPs to study, Poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV), Poly(9,9-dioctylfluorene-alt-bithiophene) (F8T2) and Poly(9,9-dioctylfluorene-alt-biselenophene) (F8Se2). In Chapter 3, data from mixed solvent experiments are known to produce biomodal distributions of spectra where chains emitting red light are thought to be in regions where chromophore aggregation is important. We showed in single molecule experiments that MEH-PPV follows the J-aggregate model where the properties of the chromophore are closely related to the conjugation length. Despite the similarity of the single molecule spectra to those observed in the bulk, fluorescence dynamics and intensities of red emitters are similar to those of blue emitters in the single molecule case. O2 mainly causes reversible quenching ("blinking") on the single MEH-PPV chains. Unfortunately, we could not reproduce flaring observed in a previous thesis and, although we had improved N2 protection and better signal to noise (S/N) ratio, we are not sure why our results are different. In Chapter 4 where we study F8T2, we also observe two distinct types of chromophores in the bulk experiments depending on the solvent quality. The photophysical properties of the F8T2 chains were well explained by the Spano HJ model. Even though spectral lineshapes of single F8T2 chains resemble those observed in the bulk, we concluded on the basis of very different emission intensity and lifetime behavior that the origin of the emission spectra is different and could be ascribed to bent chains. We argue that the propensity to bend in the F8T2 case and what makes it different than MEH-PPV derives from the presence of five-membered rings in F8T2 and we note behavioral similarities to polythiophenes that share this property. In Chapter 5, we showed that analogous CPs F8Se2 with selenium instead of sulfur in the monomer units exhibit strongly reduced fluorescence and dramatic reduction in singlet lifetime in the bulk due to heavy atom induced intersystem crossing to the triplet. Surprisingly, however, we observe substantial fluorescence and relatively strong emission in the single chain case for F8Se2. On the basis of a red shift in the spectrum and the long lifetimes relative to the bulk, we believe that the emission we are observing in this case is primarily from a photooxidized species similar to that observed in fluorene polymers. Overall, this work is a step towards looking more carefully at the complex correlation between morphology and photophysical properties. We show that bending of single chains can mimic the spectroscopy of aggregation and that it is necessary to consider fluorescence lifetime and efficiency data to distinguish between these effects. We have also used single chain spectroscopy to look at how chain morphology plays a significant role in energy transfer. In particular, we see little evidence for energy transfer in chains deposited from good solvents in contrast to some work where chains can behave as single chromophores when deposited under conditions where chains are able to collapse. We have also introduced a new way of looking at the relative propensity of different chains within a sample to blink and/or permanently photooxidize through studies correlating intensity drops and rises with spectra"--Pages x-xii.
Download or read book Photophysics of Conjugated Polymers written by Tieneke Emily Dykstra and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Conjugated Polyrotaxanes for Optoelectronic Applications written by Aurica Farcas and published by LAP Lambert Academic Publishing. This book was released on 2015-09-11 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt: The past decade has witnessed remarkable innovations and progress in polymer and supramolecular science, which offer great opportunity for new concepts, new materials with unique properties and novel practical applications. Conjugated polyrotaxanes have attracted considerable attention not only because of their architecture and topology, but also because they offer an efficient strategy towards the "insulation" of individual molecular wires. The presence of the macrocycle is essential for the control of intermolecular interactions, and conjugated polyrotaxanes may function as model compounds in the study of fundamental photophysical properties of pi-conjugated polymers. This book provides an overview of the general principles towards the synthesis and photophysical characteristics of conjugated polyrotaxanes containing as host molecules native cyclodextrins, their chemically-modified derivatives and cucurbit[7]uril. The influence of the host nature on the physical properties will also consider. The present study will be limited mainly to our own endeavours concerning three different polyrotaxane structures with noticeable advantages for optoelectronic applications.
Download or read book Photophysical Studies of Pi conjugated Oligomers and Polymers that Incorporate Inorganic MLCT Chromophores written by Keith A. Walters and published by . This book was released on 2000 with total page 504 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Photophysics of Single Chain Poly arylene Ethynylene s written by Eric Ely Silverman and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: This dissertation presents the results of an investigation into the photophysical properties of single conjugated polymers. The study focuses on the properties of polymers as single-chain "molecular wires", rather than as bulk materials. The dissertation focuses on the design and synthesis of these materials and the use of a variety of techniques to probe their unique properties. The primary focus of the photophysical investigations is the use of optical techniques, although radiolytic techniques were also applied where appropriate.
Download or read book Electronic Energy Transfer Processes and Charge Carrier Transport in Pi conjugated Polymers written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Conjugated polymers have attracted tremendous academical and industrial research interest over the past decades due to the appealing advantages that organic / polymeric materials offer for electronic applications and devices such as organic light emitting diodes (OLED), organic field effect transistors (OFET), organic solar cells (OSC), photodiodes and plastic lasers. The optimization of organic materials for applications in optoelectronic devices requires detailed knowledge of their photophysical properties, for instance energy levels of excited singlet and triplet states, excited state decay mechanisms and charge carrier mobilities. In the present work a variety of different conjugated (co)polymers, mainly polyspirobifluorene- and polyfluorene-type materials, was investigated using time-resolved photoluminescence spectroscopy in the picosecond to second time domain to study their elementary photophysical properties and to get a deeper insight into structure-property relationships. The experiments cover fluorescence spectroscopy using Streak Camera techniques as well as time-delayed gated detection techniques for the investigation of delayed fluorescence and phosphorescence. All measurements were performed on the solid state, i.e. thin polymer films and on diluted solutions. Starting from the elementary photophysical properties of conjugated polymers the experiments were extended to studies of singlet and triplet energy transfer processes in polymer blends, polymer-triplet emitter blends and copolymers. The phenomenon of photonenergy upconversion was investigated in blue light-emitting polymer matrices doped with metallated porphyrin derivatives supposing an bimolecular annihilation upconversion mechanism which could be experimentally verified on a series of copolymers. This mechanism allows for more efficient photonenergy upconversion than previously reported for polyfluorene derivatives. In addition to the above described spectroscopical experiments, amplified sp.
