Photoinduced Intramolecular Charge Transfer in Donor-Acceptor Biaryls and Resulting Applicational Aspects Regarding Fluorescent Probes and Solar Energy Conversion - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Photoinduced Intramolecular Charge Transfer in Donor-Acceptor Biaryls and Resulting Applicational Aspects Regarding Fluorescent Probes and Solar Energy Conversion write by Michael Maus. This book was released on 1998. Photoinduced Intramolecular Charge Transfer in Donor-Acceptor Biaryls and Resulting Applicational Aspects Regarding Fluorescent Probes and Solar Energy Conversion available in PDF, EPUB and Kindle. This study is focused on the effects of photoinduced intramolecular charge transfer (CT) in three differently twisted donor-acceptor (D-A) biphenyls. Taking into account a further pair of differently twisted D-A biaryls new universal insights into the photoinduced electronic and conformation dynamics of D-A biaryls are obtained. Furthermore, possible applications in fields of solar energy conversion and fluorescence sensing of microenvironments are demonstrated. Experimental means of stationary and time-resolved (ps to s) luminescence, transient absorption (sub-ps), polarization spectroscopy, high pressure and low temperature techniques are employed in conjunction with quantum chemical calculations. Twist angle and solvent dependent electron transfer (ET) interactions between the D and A aryl moieties are responsible for the low lying and solvatochromic intramolecular CT electron band which gains unusually high intensity through strong electronic coupling of the pure 1ET with the ground (S0) and 1La state. As regards the class of biaryl compounds, for the first time, an excited state electron transfer from the D to the A could be monitored by dual spectrally separated stimulated fluorescence bands with precursor-successor relationship on a sub-ps timescale for the D-A biphenyls. It is concluded that, in additon to the electronic interaction of 1ET with S0 and 1La, the electronic interaction with a close lying 1Lb state plays a fundamental role in the ET dynamics and the 1CT-S0 transition probability in D-A biaryls. The initial photoinduced conformational relaxation occurs towards planarity in all biaryls investigated. However, various results evidence that the highly twisted D-A biphenyl additionally performs a slow "excited state intramolecular back twist rotation" leading to a solvent polarity dependent conformational equilibrium between a more planar (CT) and a more twisted (CTR) conformer in S1(1CT). Using global analysis of the biexponential fluorescence decays as a function of temperature and pressure in medium polar solvents, the kinetics, thermodynamics, viscosity control and decomposed emission spectra associated with this adiabatic photoreaction are determined. The twist angle dependent ability of the D-A biphenyls to serve as fluorescent probes of micropolarity, changes of microviscosity or matrix order, protic solvents and pH is investigated. In particular, fluorescence sensing of pH seems to be promising.
Photoinduced Intramolecular Charge Transfer in Donor-receptor Biaryls and Resulting Applicational Aspects Regarding Fluorescent Probes and Solar Energy Conversion
Photoinduced Intramolecular Charge Transfer in Donor-receptor Biaryls and Resulting Applicational Aspects Regarding Fluorescent Probes and Solar Energy Conversion - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Photoinduced Intramolecular Charge Transfer in Donor-receptor Biaryls and Resulting Applicational Aspects Regarding Fluorescent Probes and Solar Energy Conversion write by Michael Maus. This book was released on 1998. Photoinduced Intramolecular Charge Transfer in Donor-receptor Biaryls and Resulting Applicational Aspects Regarding Fluorescent Probes and Solar Energy Conversion available in PDF, EPUB and Kindle.
Polymers in Organic Electronics
Polymers in Organic Electronics - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Polymers in Organic Electronics write by Sulaiman Khalifeh. This book was released on 2020-04-01. Polymers in Organic Electronics available in PDF, EPUB and Kindle. Polymers in Organic Electronics: Polymer Selection for Electronic, Mechatronic, and Optoelectronic Systems provides readers with vital data, guidelines, and techniques for optimally designing organic electronic systems using novel polymers. The book classifies polymer families, types, complexes, composites, nanocomposites, compounds, and small molecules while also providing an introduction to the fundamental principles of polymers and electronics. Features information on concepts and optimized types of electronics and a classification system of electronic polymers, including piezoelectric and pyroelectric, optoelectronic, mechatronic, organic electronic complexes, and more. The book is designed to help readers select the optimized material for structuring their organic electronic system.Chapters discuss the most common properties of electronic polymers, methods of optimization, and polymeric-structured printed circuit boards. The polymeric structures of optoelectronics and photonics are covered and the book concludes with a chapter emphasizing the importance of polymeric structures for packaging of electronic devices. Provides key identifying details on a range of polymers, micro-polymers, nano-polymers, resins, hydrocarbons, and oligomers Covers the most common electrical, electronic, and optical properties of electronic polymers Describes the underlying theories on the mechanics of polymer conductivity Discusses polymeric structured printed circuit boards, including their rapid prototyping and optimizing their polymeric structures Shows optimization methods for both polymeric structures of organic active electronic components and organic passive electronic components
Photoinduced Charge and Energy Transfer Processes in Molecular Aggregates
Photoinduced Charge and Energy Transfer Processes in Molecular Aggregates - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Photoinduced Charge and Energy Transfer Processes in Molecular Aggregates write by . This book was released on 2009. Photoinduced Charge and Energy Transfer Processes in Molecular Aggregates available in PDF, EPUB and Kindle. This project involved the experimental probing of the electronic excited states generated by photoinduced (center-to-center) electron and energy transfer processes in several classes of transition metal donor/acceptor (D/A) complexes. Some of the general properties inferred from these studies should be useful in the design of new systems for energy conversion applications. Pursuit of the project goals has involved the determination of electron transfer efficiencies and the detailed study of variations in the electronic spectra of D/A complexes. This has resulted in the study of some very fundamental issues of photoinduced charge transfer and the identification of some of the constraints on its efficiency. The experimental studies of the competition between the degradative non-radiative unimolecular relaxation of transition metal excited states and their transfer of charge from these excited states to external acceptors have involved a range of techniques such as transient decay kinetics, photoacoustic calorimetry and transient or stationary state spectroscopy. The substrates synthesized for these studies were selected to provide model systems, or series of model systems to probe the validity of models of electronic excited states and their reactivity. The work during the last few years has focused largely, but not exclusively, on the use of emission spectral band shapes to probe the properties of charge transfer (CT) excited states. Bandshape variations are one of the very few approaches for systematically probing electronic excited states and good band shape resolution is necessary in order to gain information about the structural variations that correlate with excited state reactivity. Differences in molecular structure correlate with differences in chemical reactivity, and the variations in emission bandshapes are well known to relate to variations in the molecular structural differences between the excited and ground electronic states. However, it is has been rarely noticed that configurational mixing of the lowest energy excited state with other electronic states leads to unique distortions of the lowest energy excited state which result in modifications in the vibronic structure and bandshape of the emission. We have used the emission sideband shapes to evaluate patterns of ground state-excited state and excited state-excited state configurational mixing in some simple series of complexes.
Charge-transfer and Other Excitonic State in Conjugated Polymer
Charge-transfer and Other Excitonic State in Conjugated Polymer - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Charge-transfer and Other Excitonic State in Conjugated Polymer write by Dhanashree Moghe. This book was released on 2014. Charge-transfer and Other Excitonic State in Conjugated Polymer available in PDF, EPUB and Kindle. Over the last few decades there has been tremendous progress in organic photovoltaics (OPVs), with efficiencies reaching over 10%. Still, many factors including the origin and the dynamics of charge carrier involved are debatable. New and sensitive techniques are constantly being devised to identify the origin of free charges. At the same time, a lot of research has also been devoted to synthesize low bandgap material such that its absorption spectra overlap with that of the solar spectrum. The most important hindrance in organic semiconductors is the formation of bound electron-hole (exciton) charge pair upon photoexcitation. Additional energy is required to dissociate the bound pair to generate free charges for photovoltaic application. The most popular and efficient way to dissociate excitons is to fabricate a bulk heterojunction solar cell, which comprises of a blend of at least two polymers: one donor and the other acceptor. It is very well established that the presence of fullerene (acceptor) helps in transfer of the negative charges from the donor polymer to fullerene, making the exciton slightly less bound. The nanometer scale islands further help in migration of charges. A crucial aspect of our studies has been evaluating the role of various excitonic states such as charge-transfer and triplet excitonic states in device efficiencies. The focus of this work was on diketopyrrolopyrrole (DPP)- based donor-acceptor (D-A) type conjugated copolymers which have low bandgap energies and have been known to show high efficiency in organic photovoltaics. These copolymers have D-A unit present in the same chain, which lowers the optical bandgap of the material. Variation of either the donor or the acceptor fraction offers an option to tune the optical bandgap by using the same D-A chromophores. The D-A configuration also results in the separation of positive and negative charges within the same polymeric chain, which is the intramolecular charge-transfer excitonic state. We analyze the intramolecular charge-transfer state using bias dependent absorption studies, which allowed us to estimate the binding energy of intramolecular exciton. Later, we performed density functional theory (DFT) and time dependent DFT calculations to identify the origin of the intramolecular exciton absorption. Taking the copolymers as donor (and fullerene as acceptor) in an organic photovoltaic device, we probe the (intermolecular) charge-transfer states formed at the copolymer/fullerene interface . We utilize monochromatic photocurrent method and a highly sensitive (and fast) Fourier transform photocurrent spectroscopy technique to probe the intermolecular charge-transfer states in the device. Our analyses show that the optical bandgap difference between the copolymers and fullerene plays a pivotal role in stabilization /destabilization of charge - transfer states in copolymer-fullerene systems. The triplet excitons are also known to play an important role in OPV efficiency. We probe the diffusion length of triplet exciton in ladder-type polymers by devising a simple, yet efficient method using optical modulation spectroscopy (photoinduced absorption spectroscopy). The diffusion length of triplet excitons is estimated to be almost three orders of magnitude more than the singlet excitons . Further, by implementing a 1D random-walk model to the photoinduced absorption data, we estimate diffusivities of the triplet exciton in our sample.
