Relevant bibliographies by topics / Pai-Conjugated Molecular Materials Electronic Structure

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  1. Journal articles
  2. Dissertations / Theses
  3. Book chapters
  4. Conference papers

Academic literature on the topic 'Pai-Conjugated Molecular Materials Electronic Structure'

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Published: 4 June 2021
Last updated: 7 September 2023

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Journal articles on the topic "Pai-Conjugated Molecular Materials Electronic Structure"

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Men, Xiaoju, and Zhen Yuan. "Multifunctional conjugated polymer nanoparticles for photoacoustic-based multimodal imaging and cancer photothermal therapy." Journal of Innovative Optical Health Sciences 12, no. 03 (May 2019): 1930001. http://dx.doi.org/10.1142/s1793545819300015.

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Photoacoustic imaging (PAI) is a hybrid imaging method based on photoacoustic (PA) effects, which is able to capture the structure, function, and molecular information of biological tissues with high resolution. To date, therapeutic techniques under the guidance of PAI have provided new strategies for accurate diagnosis and precise treatment of tumors. In particular, conjugated polymer nanoparticles have been extensively inspected for PA-based cancer theranostics largely due to their superior optical properties such as tunable spectrum and large absorption coefficient and their good biocompatibility, and abundant functional groups. This mini-review mainly focuses on the recent advances toward the development of novel conjugated polymer nanoparticles for PA-based multimodal imaging and cancer photothermal therapy.
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Caciuc, V., M. C. Lennartz, N. Atodiresei, S. Karthäuser, and S. Blügel. "Fine tuning of the electronic structure of π-conjugated molecules for molecular electronics." Nanotechnology 22, no. 14 (February 24, 2011): 145701. http://dx.doi.org/10.1088/0957-4484/22/14/145701.

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Dong, Xiaodi, Mingsheng Zheng, Baoquan Wan, Xuejie Liu, Haiping Xu, and Junwei Zha. "Low—Permittivity Copolymerized Polyimides with Fluorene Rigid Conjugated Structure." Materials 14, no. 21 (October 21, 2021): 6266. http://dx.doi.org/10.3390/ma14216266.

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As the miniaturization of electronic appliances and microprocessors progresses, low-permittivity interlayer materials are becoming increasingly important for their suppression of electronic crosstalk, signal propagation delay and loss, and so forth. Herein, a kind of copolyimide (CPI) film with a “fluorene” rigid conjugated structure was prepared successfully. By introducing 9,9-Bis(3-fluoro-4-aminophenyl) fluorene as the rigid conjugated structure monomer, a series of CPI films with different molecular weights were fabricated by in situ polymerization, which not only achieved the reduction of permittivity but also maintained excellent thermodynamic stability. Moreover, the hydrophobicity of the CPI film was also improved with the increasing conjugated structure fraction. The lowest permittivity reached 2.53 at 106 Hz, while the thermal decomposition temperature (Td5%) was up to 530 °C, and the tensile strength was ≥ 96 MPa. Thus, the CPI films are potential dielectric materials for microelectronic and insulation applications.
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Lin, Chia-Yang, and Tsuyoshi Michinobu. "Conjugated photothermal materials and structure design for solar steam generation." Beilstein Journal of Nanotechnology 14 (April 4, 2023): 454–66. http://dx.doi.org/10.3762/bjnano.14.36.

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With the development of solar steam generation (SSG) for clean water production, conjugated photothermal materials (PTMs) have attracted significant interest because of their advantages over metallic and inorganic PTMs in terms of high light absorption, designable molecular structures, flexible morphology, and solution processability. We review here the recent progress in solar steam generation devices based on conjugated organic materials. Conjugated organic materials are processed into fibers, membranes, and porous structures. Therefore, nanostructure design based on the concept of nanoarchitectonics is crucial to achieve high SSG efficiency. We discuss the considerations for designing SSG absorbers and describe commonly used conjugated organic materials and structural designs.
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Kim, Jinsang. "Assemblies of conjugated polymers: Intermolecular and intramolecular effects on the photophysical properties of conjugated polymers." Pure and Applied Chemistry 74, no. 11 (January 1, 2002): 2031–44. http://dx.doi.org/10.1351/pac200274112031.

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Conjugated polymers are emerging materials for electronic applications due to the tunability of their properties through variation of their chemical structure. Their applications, which currently include light-emitting diodes (LEDs), field effect transistors (FETs), plastic lasers, batteries, and sensors, are expanding to many new areas. The two critical parameters that determine the function of conjugated polymer-based devices are chemical structure and nanostructure of a conjugated polymer in the solid state. While the physical properties of isolated polymers are primarily controlled by their chemical structure, these properties are drastically altered in the solid state due to electronic coupling between polymer chains as determined by their interpolymer packing and conformation. However, the development of effective and precise methods for controlling the nanostructure of polymers in the solid state has been limited because polymers often fail to assemble into organized structures due to their amorphous character and large molecular weight.In this review, recent developments of organizing methods of conjugated polymers and the conformation and interpolymer interaction effects on the photophysical properties of conjugated polymers are summarized.
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Salaneck, W. R., and J. L. Brédas. "Conjugated Polymer Surfaces and Interfaces for Light-Emitting Devices." MRS Bulletin 22, no. 6 (June 1997): 46–51. http://dx.doi.org/10.1557/s0883769400033625.

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Since the discovery of high electrical conductivity in doped polyacetylene in 1977, π-conjugated polymers have emerged as viable semiconducting electronic materials for numerous applications. In the context of polymer electronic devices, one must understand the nature of the polymer surface's electronic structure and the interface with metals. For conjugated polymers, photoelectron spectroscopy—especially in connection with quantum-chemical modeling—provides a maximum amount of both chemical and electronic structural information in one (type of) measurement. Some details of the early stages of interface formation with metals on the surfaces of conjugated polymers and model molecular solids in connection with polymer-based light-emitting devices (LEDs) are outlined. Then a chosen set of issues is summarized in a band structure diagram for a polymer LED, based upon a “clean calcium electrode” on the clean surface of a thin film of poly(p-phenylene vinylene) (PPV). This diagram helps to point out the complexity of the systems involved in polymer LEDs. No such thing as “an ideal metal-on-polymer contact” exists. There is always some chemistry occurring at the interface.
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Miao, Zongcheng, Yaqin Chu, Lei Wang, Wenqing Zhu, and Dong Wang. "Nonlinear Optical and Ion Sensor Properties of Novel Molecules Conjugated by Click Chemistry." Polymers 14, no. 8 (April 8, 2022): 1516. http://dx.doi.org/10.3390/polym14081516.

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The molecular structure, luminescence behavior, and electronic energy level of an organic optoelectronic materials are important parameters for its synthesis. The electro-optical properties can be changed by modifying the structure of the molecule to make the electronic energy level adjustable. In this article, a series of organic conjugated micro-molecules are successfully synthesized by linking small compound units. This metal-free [2 + 2] click chemistry process generates donor–acceptor chromophore substances with high yield, high solubility, and adjustable energy levels, which can be widely used for sensors and nonlinear optics in different fields. A-TCNE, A-TCNQ, and A-F4-TCNQ molecules are characterized comprehensively via UV-Vis-NIR spectra, 1H NMR spectra, infrared spectroscopy, and mass spectrometry. The unique nonlinear optical phenomena and powerful intra-molecular charge–transfer interactions of these new materials give them fascinating potential for application as optoelectronic materials.
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Kahn, Antoine, Norbert Koch, and Weiying Gao. "Electronic structure and electrical properties of interfaces between metals and ?-conjugated molecular films." Journal of Polymer Science Part B: Polymer Physics 41, no. 21 (October 8, 2003): 2529–48. http://dx.doi.org/10.1002/polb.10642.

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Matt, Clemens, Florian Lombeck, Michael Sommer, and Till Biskup. "Impact of Side Chains of Conjugated Polymers on Electronic Structure: A Case Study." Polymers 11, no. 5 (May 13, 2019): 870. http://dx.doi.org/10.3390/polym11050870.

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Processing from solution is a crucial aspect of organic semiconductors, as it is at the heart of the promise of easy and inexpensive manufacturing of devices. Introducing alkyl side chains is an approach often used to increase solubility and enhance miscibility in blends. The influence of these side chains on the electronic structure, although highly important for a detailed understanding of the structure-function relationship of these materials, is still barely understood. Here, we use time-resolved electron paramagnetic resonance spectroscopy with its molecular resolution to investigate the role of alkyl side chains on the polymer PCDTBT and a series of its building blocks with increasing length. Comparing our results to the non-hexylated compounds allows us to distinguish four different factors determining exciton delocalization. Detailed quantum-chemical calculations (DFT) allows us to further interpret our spectroscopic data and to relate our findings to the molecular geometry. Alkylation generally leads to more localized excitons, most prominent only for the polymer. Furthermore, singlet excitons are more delocalized than the corresponding triplet excitons, despite the larger dihedral angles within the backbone found for the singlet-state geometries. Our results show TREPR spectroscopy of triplet excitons to be well suited for investigating crucial aspects of the structure-function relationship of conjugated polymers used as organic semiconductors on a molecular basis.
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Gong, Pingping, Lili An, Junfeng Tong, Xinpeng Liu, Zezhou Liang, and Jianfeng Li. "Design of A-D-A-Type Organic Third-Order Nonlinear Optical Materials Based on Benzodithiophene: A DFT Study." Nanomaterials 12, no. 20 (October 21, 2022): 3700. http://dx.doi.org/10.3390/nano12203700.

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The acceptor-donor-acceptor (A-D-A) type conjugated organic molecule has been widely applied in the organic optoelectronics field. A total of Nine compounds (1–9) were designed under the A-D-A framework, with the electron donor benzodithiophene as the core and dicyanomethylene as the acceptor moiety, modifying the benzodithiophene with the phenyl, naphthyl, and difluorinated phenyl groups. The conjugation length can be changed by introducing a thiophene π-conjugated bridge. The geometric structures, electronic structure, excited state properties, aromaticity, and the static- and frequency-dependent second hyperpolarizabilities were investigated by employing high-precision density functional theory (DFT) calculations with an aug-cc-pVDZ basis set. As a result, the three compounds with the longest conjugation length exhibit a smaller energy gap (Egap), larger UV-vis absorption coefficient, and response range, which are the three strongest third-order nonlinear optical (NLO) response properties in this work. This work systematically explored the connection between molecular structure and NLO response, which provides a rational design strategy for high-performance organic NLO materials.
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Dissertations / Theses on the topic "Pai-Conjugated Molecular Materials Electronic Structure"

1

Prodhan, Suryoday. "Theoretical Investigation of OPTO-Electronic Processes in Organic Conjugated Systems Within Interacting Models : Exact Diagonalization and DMRG Studies." Thesis, 2017. http://etd.iisc.ac.in/handle/2005/3565.

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The present thesis deals with a theoretical study of electronic structures in -conjugated molecular materials with focus on their application in organic elec-tronics. We also discuss a modified and efficient symmetrized DMRG algorithm for studying excited states in these systems. In recent times, organic conjugated systems have emerged as potential candidates in a wide range of fascinating fields by virtue of their tunable electronic properties, easy processability and low cost. Tunability in the electronic and optical properties primarily are centered on the or-dering and nature of the low-lying excited states. Probing these important excited states also demands development of efficient and adaptable techniques. Chapter 1 provides a basic overview of conjugated organic polymers which have been utilized over decades in diverse fields as in organic light emitting diodes (OLED), organic solar cells (OSC) and non-linear optical (NLO) devices. These systems also contribute significantly to theoretical understanding as they pro vide important insights of one and quasi-one dimensional systems. In this chapter, we have given basic description of the electronic processes in OLED and OSC along with a brief theoretical description of -conjugated organic systems. Chapter 2 gives an account of the numerical techniques which are necessary for the study of low-dimensional strongly correlated systems like -conjugated sys-tems. For this purpose, effective low-energy model Hamiltonians viz. Huckel,¨ Hubbard and Pariser-Parr-Pople Hamiltonians are discussed. Exact diagonalization technique within the diagrammatic valence bond (DVB) basis and density matrix renormalization group (DMRG) technique are discussed in details. We have also given brief accounts of the methods employed to study real-time dynamics. A short description of different computational techniques for the study of NLO properties in -conjugated systems is also provided. Engineering the position of the lowest triplet state (T1) relative to the first excited singlet state (S1) is of great importance in improving the efficiencies of organic light emitting diodes and organic photovoltaic cells. In chapter 3, we have carried out model exact calculations of substituted polyene chains to understand the fac-tors that affect the energy gap between S1 and T1. The factors studied are backbone dimerization, different donor-acceptor substitutions and twisted backbone geome-try. The largest system studied is an eighteen carbon polyene which spans a Hilbert space of about 991 million in the triplet subspace. We show that for reverse inter-system crossing (RISC) process, the best choice involves substituting all carbon sites on one half of the polyene with donors and the other half with acceptors. Singlet fission (SF) is a potential pathway for significant enhancement of efficiency in OSC. In chapter 4, we study singlet fission in a pair of polyene molecules in two different stacking arrangements employing exact many-body wave packet dy-namics. In the non-interacting model, SF is absent. The individual molecules are treated within Hubbard and Pariser-Parr-Pople (PPP) models and the interac-tion between them involves transfer terms, intersite electron repulsions and site-charge—bond-charge repulsion terms. Initial wave packet is construc ted from ex-cited singlet state of one molecule and ground state of the other. Time develop-ment of this wave packet under the influence of intermolecular interactions is fol-lowed within the Schrodinger¨ picture by an efficient predictor-corrector scheme. In unsubstituted Hubbard and PPP chains, 21A state leads to significant SF yield while the 11B state gives negligible fission yield. On substitution by donor-acceptor groups of moderate strength, the lowest excited state will have sufficient 2 1A char-acter and hence gives significant SF yield. Because of rapid internal c onversion, the nature of the lowest excited singlet will determine the SF contribution to OSC effi - ciency. Furthermore, we find the fission yield depends considerably on th e stacking arrangement of the polyene molecules. In chapter 5, we have given an account of a new modified algorithm for symmetry adaptation within symmetrized density matrix renormalization group (SDMRG) technique. SDMRG technique has been an efficient method for studying low-lying eigenstates in one and quasi-one dimensional electronic systems. However, SDMRG method until now, had bottlenecks involving construction of linearly in-dependent symmetry adapted basis states as the symmetry matrices in the DMRG basis were not sparse. Our modified algorithm overcomes this bottleneck. T he new method incorporates end-to-end interchange symmetry (C2), electron-hole symmetry (J) and parity or spin-flip symmetry (P) in these calculations. The one-to-one correspondence between direct-product basis states in the DMRG Hilbert space for these symmetry operations renders the symmetry matrices in the new ba-sis with maximum sparseness, just one non-zero matrix element per row. Using methods similar to those employed in exact diagonalization technique for Pariser-Parr-Pople (PPP) models, developed in the eighties, it is possible to construct or-thogonal SDMRG basis states while bypassing the slow step of Gram-Schmidt orthonormalization procedure. The method together with the PPP model which incorporates long-range electronic correlations is employed to study the correlated excited states of 1,12-benzoperylene. In chapter 6, we have studied the correlated excited states of coronene and ova-lene within Pariser-Parr-Pople (PPP) model employing symmetry adapted density matrix renormalization group technique. These polynuclear aromatic hydrocar-bons can be considered as graphene nanoflakes and study of their ele ctronic struc-tures will shed light on the electron correlation effects in these finite-size gr aphene analogues. The electron correlation effect usually diminishes on going from one-dimensional to higher-dimensional systems, yet, it is significant within these fin ite-size graphene derivatives where it depends on the molecular topology. We have characterized these low-lying energy states by calculating bond orders, spin den-sities in the lowest triplet state and two-photon absorption cross-sections for low-lying two-photon states. vi
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2

Prodhan, Suryoday. "Theoretical Investigation of OPTO-Electronic Processes in Organic Conjugated Systems Within Interacting Models : Exact Diagonalization and DMRG Studies." Thesis, 2017. http://etd.iisc.ernet.in/2005/3565.

Full text
Abstract:
The present thesis deals with a theoretical study of electronic structures in -conjugated molecular materials with focus on their application in organic elec-tronics. We also discuss a modified and efficient symmetrized DMRG algorithm for studying excited states in these systems. In recent times, organic conjugated systems have emerged as potential candidates in a wide range of fascinating fields by virtue of their tunable electronic properties, easy processability and low cost. Tunability in the electronic and optical properties primarily are centered on the or-dering and nature of the low-lying excited states. Probing these important excited states also demands development of efficient and adaptable techniques. Chapter 1 provides a basic overview of conjugated organic polymers which have been utilized over decades in diverse fields as in organic light emitting diodes (OLED), organic solar cells (OSC) and non-linear optical (NLO) devices. These systems also contribute significantly to theoretical understanding as they pro vide important insights of one and quasi-one dimensional systems. In this chapter, we have given basic description of the electronic processes in OLED and OSC along with a brief theoretical description of -conjugated organic systems. Chapter 2 gives an account of the numerical techniques which are necessary for the study of low-dimensional strongly correlated systems like -conjugated sys-tems. For this purpose, effective low-energy model Hamiltonians viz. Huckel,¨ Hubbard and Pariser-Parr-Pople Hamiltonians are discussed. Exact diagonalization technique within the diagrammatic valence bond (DVB) basis and density matrix renormalization group (DMRG) technique are discussed in details. We have also given brief accounts of the methods employed to study real-time dynamics. A short description of different computational techniques for the study of NLO properties in -conjugated systems is also provided. Engineering the position of the lowest triplet state (T1) relative to the first excited singlet state (S1) is of great importance in improving the efficiencies of organic light emitting diodes and organic photovoltaic cells. In chapter 3, we have carried out model exact calculations of substituted polyene chains to understand the fac-tors that affect the energy gap between S1 and T1. The factors studied are backbone dimerization, different donor-acceptor substitutions and twisted backbone geome-try. The largest system studied is an eighteen carbon polyene which spans a Hilbert space of about 991 million in the triplet subspace. We show that for reverse inter-system crossing (RISC) process, the best choice involves substituting all carbon sites on one half of the polyene with donors and the other half with acceptors. Singlet fission (SF) is a potential pathway for significant enhancement of efficiency in OSC. In chapter 4, we study singlet fission in a pair of polyene molecules in two different stacking arrangements employing exact many-body wave packet dy-namics. In the non-interacting model, SF is absent. The individual molecules are treated within Hubbard and Pariser-Parr-Pople (PPP) models and the interac-tion between them involves transfer terms, intersite electron repulsions and site-charge—bond-charge repulsion terms. Initial wave packet is construc ted from ex-cited singlet state of one molecule and ground state of the other. Time develop-ment of this wave packet under the influence of intermolecular interactions is fol-lowed within the Schrodinger¨ picture by an efficient predictor-corrector scheme. In unsubstituted Hubbard and PPP chains, 21A state leads to significant SF yield while the 11B state gives negligible fission yield. On substitution by donor-acceptor groups of moderate strength, the lowest excited state will have sufficient 2 1A char-acter and hence gives significant SF yield. Because of rapid internal c onversion, the nature of the lowest excited singlet will determine the SF contribution to OSC effi - ciency. Furthermore, we find the fission yield depends considerably on th e stacking arrangement of the polyene molecules. In chapter 5, we have given an account of a new modified algorithm for symmetry adaptation within symmetrized density matrix renormalization group (SDMRG) technique. SDMRG technique has been an efficient method for studying low-lying eigenstates in one and quasi-one dimensional electronic systems. However, SDMRG method until now, had bottlenecks involving construction of linearly in-dependent symmetry adapted basis states as the symmetry matrices in the DMRG basis were not sparse. Our modified algorithm overcomes this bottleneck. T he new method incorporates end-to-end interchange symmetry (C2), electron-hole symmetry (J) and parity or spin-flip symmetry (P) in these calculations. The one-to-one correspondence between direct-product basis states in the DMRG Hilbert space for these symmetry operations renders the symmetry matrices in the new ba-sis with maximum sparseness, just one non-zero matrix element per row. Using methods similar to those employed in exact diagonalization technique for Pariser-Parr-Pople (PPP) models, developed in the eighties, it is possible to construct or-thogonal SDMRG basis states while bypassing the slow step of Gram-Schmidt orthonormalization procedure. The method together with the PPP model which incorporates long-range electronic correlations is employed to study the correlated excited states of 1,12-benzoperylene. In chapter 6, we have studied the correlated excited states of coronene and ova-lene within Pariser-Parr-Pople (PPP) model employing symmetry adapted density matrix renormalization group technique. These polynuclear aromatic hydrocar-bons can be considered as graphene nanoflakes and study of their ele ctronic struc-tures will shed light on the electron correlation effects in these finite-size gr aphene analogues. The electron correlation effect usually diminishes on going from one-dimensional to higher-dimensional systems, yet, it is significant within these fin ite-size graphene derivatives where it depends on the molecular topology. We have characterized these low-lying energy states by calculating bond orders, spin den-sities in the lowest triplet state and two-photon absorption cross-sections for low-lying two-photon states. vi
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(8407140), Saadia T. Chaudhry. "CHAIN-LENGTH PROPERTIES OF CONJUGATED SYSTEMS: STRUCTURE, CONFORMATION, AND REDOX CHEMISTRY." Thesis, 2021.

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The development of solution-processable semiconducting polymers has brought mankind’s long-sought dream of plastic electronics to fruition. Their potential in the manufacturing of lightweight, flexible yet robust, and biocompatible electronics has spurred their use in organic transistors, photovoltaics, electrochromic devices, batteries, and sensors for wearable electronics. Yet, despite the successful engineering of semiconducting polymers, we do not fully understand their molecular behavior and how it influences their doping (oxidation/reduction) properties. This is especially true for donor-acceptor (D-A) p-systems which have proven to be very efficient at tuning the electronic properties of organic semiconductors. Historically, chain-length dependent studies have been essential in uncovering the relationship between the molecular structure and polymer properties. Discussed here is the systematic investigation of a complete D-A molecular series composed of monodispersed and well-defined conjugated molecules ranging from oligomer (n=3-21) to polymer scale lengths. Structure-property relationships are established between the molecular structure, chain conformation, and redox-active opto-electronic properties for the molecular series in solution. This research reveals a rod-to-coil transition at the 15 unit chain length, or 4500 Da, in solution. The redox-active optical and electronic properties are investigated as a function of increasing chain-length, giving insight into the nature of charge carriers in a D-A conjugated system. This research aids in understanding the solution behavior of conjugated organic materials.
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Book chapters on the topic "Pai-Conjugated Molecular Materials Electronic Structure"

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Lazzaroni, R., M. Lögdlund, S. Stafström, W. R. Salaneck, D. D. C. Bradley, R. H. Friend, N. Sato, E. Orti, and J. L. Bredas. "Electronic Structure of Processable Conducting Polymers." In Conjugated Polymeric Materials: Opportunities in Electronics, Optoelectronics, and Molecular Electronics, 149–62. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-2041-5_11.

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Toussaint, J. M., F. Meyers, and J. L. Bredas. "Linear Polyenes: The Interplay between Electronic Structure, Geometric Structure, and Nonlinear Optical Properties." In Conjugated Polymeric Materials: Opportunities in Electronics, Optoelectronics, and Molecular Electronics, 207–19. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-2041-5_15.

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Eckhardt, H., K. Y. Jen, L. W. Shacklette, and S. Lefrant. "Vinylene-Linked Low-Band-Gap Conducting Polymers: Electronic Structure And Defects." In Conjugated Polymeric Materials: Opportunities in Electronics, Optoelectronics, and Molecular Electronics, 305–20. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-2041-5_23.

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Bodart, V. P., J. Delhalle, and J. M. André. "Electronic Structure and Static Electric Dipole Polarizability of Acetylenic Analogs of Carbocyanines." In Conjugated Polymeric Materials: Opportunities in Electronics, Optoelectronics, and Molecular Electronics, 509–16. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-2041-5_40.

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Salaneck, W. R., R. Lazzaroni, N. Sato, M. Lögdlund, B. Sjögren, M. P. Keane, S. Svensson, A. Naves Brito, N. Correia, and S. Lunell. "The Electronic and Chemical Structure of Poly(3-Hexyl-Thiophene) Studied by Photoelectron Spectroscopy." In Conjugated Polymeric Materials: Opportunities in Electronics, Optoelectronics, and Molecular Electronics, 101–13. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-2041-5_7.

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Iucci, G., K. Xing, C. W. Spangler, M. Lögdlund, A. Holmes, and W. R. Salaneck. "Chemical and Electronic Structure of Interfaces with Conjugated Polymers: Systems of Interest in Molecular Electronics Applications." In Polymers and Other Advanced Materials, 335–46. Boston, MA: Springer US, 1995. http://dx.doi.org/10.1007/978-1-4899-0502-4_34.

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Zaier, Rania, and Sahbi Ayachi. "Designing Well-Organized Donor-Bridge-Acceptor Conjugated Systems Based on Cyclopentadithiophene as Donors in Bulk Heterojunction Organic Solar Cells: DFT-Based Modeling and Calculations." In Solar Cells - Theory, Materials and Recent Advances. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.94874.

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Two host materials based on CPDT as donors in bulk heterojunction organic solar cells were designed and investigated by means of DFT calculations. The first one (P-CPDTBT3) is a copolymer with D-A configuration and the second one (SM-CPDTDPP) is a D-π-A-π-D type small molecule. The investigated materials exhibited interesting structural properties with high planarity and rigidity originated from intra-molecular non-covalent interactions between the different building blocks. Thanks to their narrow band gaps, the optical absorption spectra have covered the main part of solar spectrum of interest. In addition, some general transport properties have been established. The transition density matrix (TDM) was used to get insight into the interaction of hole–electron localization and the electronic excitation processes. The photovoltaic parameters (FF, Voc) were calculated. The obtained results have been attempted to provide novel structure–property relationships for the rational design strategies of high-performance photovoltaic materials with power conversion efficiency of nearly 10%.
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Zaier, Rania, and Sahbi Ayachi. "Computational Study on Optoelectronic Properties of Donor-Acceptor Type Small π-Conjugated Molecules for Organic Light-Emitting Diodes (OLEDs) and Nonlinear Optical (NLO) Applications." In Density Functional Theory - Recent Advances, New Perspectives and Applications. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.98590.

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Recently, donor-acceptor type molecule that contains electron-rich (D) and electron-deficient (A) moiety has emerged as an interesting approach of molecular design strategy to develop organic light-emitting diodes (OLEDs) and non-linear optical (NLO) devices. In this work, we report a theoretical investigation based on two donor-acceptor (D-A) type small π-conjugated molecules based on dithieno [3,2-b: 2′,3′-d] pyrrole (DTP) and anthracene derivatives. All of the theoretical calculations were performed by Density Functional Theory (DFT) approach at B3LYP/6-31 g(d) level of theory. The structural, electronic, optical and charge transfer properties were investigated. The effect of acceptor blocks (DPA and DTA) on the molecular characteristics was elucidated. The obtained results clearly show that the studied compounds exhibit non-coplanar structures with low electronic band gap values. These relevant structures exhibited important optical absorption and intense emission in the green-yellow region. NLO investigation based on static polarizability (α0), first-order hyperpolarizability (β0) and second-order hyperpolazabilty (ɣ0) demonstrated that the studied materials exhibit excellent NLO properties. Thus, the designed materials showed promising capabilities to be utilized in OLED and NLO applications.
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Chemek, Mourad, Ali Mabrouk, Mourad Ben Braieck, Jany Wérry Ventirini, and Alimi Kamel. "Synthesis, Experimental and Theoretical Investigations on the Optical and Electronic Properties of New Organic Active Layer for a New Generation of Organic Light-Emitting Diode." In Nanocomposite Materials for Biomedical and Energy Storage Applications. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.103807.

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In this chapter, we present new attempts for the development of a new generation of high-performance organic light-emitting diodes (OLEDs). First of all, we present two strategies for obtaining a luminescent active layer. The first one is the chemical synthesis of a block copolymer based on the cross-linked Poly (N-vinyl carbazole) (PVK) and the conjugated poly(3-methylthiophene) (PMeT) system. Secondly, newly small luminescent organic molecules are chemically synthesized and studied. Photo-physical and electronic properties of the synthesized organic materials are fully investigated through experimental analysis and theoretical computations using essentially DFT and TDDFT methodologies. Optical measurements revealed the formation of a new highly luminescent organic material. Furthermore, the newly synthesized small molecules showed a high emission in the blue part. Based on the synthesized active layers, newly multi-structure OLED architectures are theoretically designed by the insertion of a single-walled carbon nanotube (SWCNTs) as a single layer. The theoretical computations show that the insertion of single-walled carbon nanotubes (SWCNTs) single layer improves the injection of electron charge carriers from the chosen cathode (Ca, Mg) to the synthesized active layers, which enhances the performance of the electronic focused devices based on the organic synthesized active layer.
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Conference papers on the topic "Pai-Conjugated Molecular Materials Electronic Structure"

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Paiva, Laura Simonassi Raso de, Leonardo Evaristo de Sousa, and Pedro Henrique de Oliveira Neto. "Energy transport in conjugated polymers: electronic structure and kinetic Monte Carlo simulations." In VIII Simpósio de Estrutura Eletrônica e Dinâmica Molecular. Universidade de Brasília, 2020. http://dx.doi.org/10.21826/viiiseedmol202076.

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Conjugated polymers are materials that have attracted much attention from the research community because of their charge and energy transport properties. In this sense, it is necessary to understand the mechanism behind exciton transfer in this particular class of systems. However, direct application of procedures done for different organic compounds is not straightforward for long polymeric chains, because such procedures would be computationally impracticable. In that matter, alternative treatments are required. In this work, we perform spectrum simulations for poly-thiophene (PTH) and poly(p-phenylene vinylene) (PPV) chains by analyzing the evolution of electronic properties with oligomer sizes and its effects on exciton diffusion. Furthermore, employing a kinetic Monte Carlo model, we also investigate the efficiency of intrachain exciton diffusion. Our results show a reliable description of the optical properties for long polymeric chains, and a comparison is made between the different approaches in describing the optical properties of such polymers. This study may be useful in the development of more sophisticated optoelectronic devices that use conjugated polymers as its active materials.
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Tykwinski, Rik R., Martin Schreiber, Rolf Spreiter, Christian Bosshard, Corinne Boudon, Jean-Paul Gisselbrecht, François Diederich, Peter Günter, and Maurice Gross. "Donor-Acceptor Systems Derived from Tetraethynylethene." In Organic Thin Films for Photonic Applications. Washington, D.C.: Optica Publishing Group, 1995. http://dx.doi.org/10.1364/otfa.1995.md.3.

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An increasing number of conjugated, organic molecules and polymers are finding application as materials for electronics and photonics due to their inherent synthetic flexibility, potential ease of processing and the possibility of tailoring material characteristics to suit a desired property.1 To more efficiently design organic materials to specific tasks, it is necessary to understand how and to what degree alteration of molecular electronic structure affects materials properties. Investigation of a comprehensive series of synthetically related molecules and the relationship between their electronic and physical properties is perhaps the best approach to the rational design of useful organic materials. Hence, we have synthesized a complete series of conjugated, electronically varied molecules based on a tetraethynylethene (TEE, 1) framework. Study of the optical and electrical properties of these electronically diverse building blocks will aid in tuning specific properties for the ultimate formation of functionalized polytriacetylenes (PTAs, 2).
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Prasad, Paras N. "Optical Nonlinearities of Polymers." In Nonlinear Optical Properties of Materials. Washington, D.C.: Optica Publishing Group, 1988. http://dx.doi.org/10.1364/nlopm.1988.tuc4.

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This talk will include selective results from our comprehensive program in nonlinear optical effects in organic molecules and polymers. We have calculated microscopic nonlinearities of organic molecules in several series of conjugated structures using ab-initio SCF approach coupled with the finite field method. The effects of increase in the II - electron conjugation length, molecular conformation, heavy atom effect and the role of substitutes have been investigated in order to derive an understanding of molecular structure-property relation so that structural parameters associated with enhanced optical nonlinearities can be identified. This theoretical study has been complemented with the measurements of optical nonlinearities in sequentially built and systematically derivatized structures.
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Ehrlich, J., A. Heikal, Z. Y. Hu, I. Y. S. Lee, S. R. Marder, J. W. Perry, H. Röckel, and X. L. Wu. "Nonlinear Spectroscopy and Applications of Two-Photon Absorbing Molecules." In Organic Thin Films for Photonic Applications. Washington, D.C.: Optica Publishing Group, 1997. http://dx.doi.org/10.1364/otfa.1997.tha.3.

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Molecules exhibiting strong two-photon absorption hold great potential for a wide range of applications including: two-photon fluorescence microscopy, three-dimensional (3D) optical data storage, 3D microfabrication, and optical limiting. (1-4) From a fundamental point of view, knowledge of molecular two-photon spectra and structure/property relationships are also important for a more complete understanding of the third order polarizabilities of conjugated molecules. However, very little is known or understood about two-photon states and spectra of conjugated molecules or how they correlate with structure. We have observed large two-photon absorptivities in bis-donor diphenylpolyene derivatives, that appears to be correlated to simultaneous charge transfer from the end groups to the pi-conjugated bridge in the molecule. These molecules are also excellent photoexcitable electron donors that can initiate charge-transfer reactions. In initial applications of these materials we have demonstrated their use in two-photon initiation of polymerization and optical limiting.
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Wu, J. W., R. A. Norwood, J. R. Heflin, K. Y. Wong, O. Zamani-Khamiri, and A. F. Garito. "Nonlinear Optical Processes in Lower Dimensional Conjugated Structures." In Nonlinear Optical Properties of Materials. Washington, D.C.: Optica Publishing Group, 1988. http://dx.doi.org/10.1364/nlopm.1988.mb5.

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Strong correlation between π-electrons in effectively reduced spatial dimensions[1] is a guiding concept in designing organic materials possessing large nonlinear optical responses. Microscopic descriptions of second βijk(-ω3;ω1,ω2) and third γijkl(-ω4;ω1,ω2,ω3) order π-electron virtual excitation processes are required in order to understand at a fundamental level the physical properties and behavior of βijk and γijkl and to provide guidelines for molecular designs of new material structures. The purpose of this paper is to report recent developments concerning the origin and mechanisms for γijkl of quasi-1D conjugated structures and recent observations of optical bistability in quasi-2D structures.
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Keogh, S. M. "Physical Interactions between HiPco SWNTs and Semi-Conjugated Polymers." In STRUCTURAL AND ELECTRONIC PROPERTIES OF MOLECULAR NANOSTRUCTURES: XVI International Winterschool on Electronic Properties of Novel Materials. AIP, 2002. http://dx.doi.org/10.1063/1.1514185.

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Szablewski, Marek, Philip Thomas, Graham Cross, and Jacqueline Cole. "Structural and solvatochromic studies of a series of chromophoric TCNQ derivatives with large second order nonlinearities." In Organic Thin Films for Photonic Applications. Washington, D.C.: Optica Publishing Group, 1995. http://dx.doi.org/10.1364/otfa.1995.md.32.

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As a result of our discovery of a novel reaction of TCNQ with triethylamine1 which led to the synthesis of DEMI (structure I, fig. 1)2, we have prepared a range of similar adducts of TCNQ with tertiary ethyl amines (structures I - VII). All of these adducts have similar structural components, a dicyanomethanide group separated from an electron deficient amino moiety by an aromatic/quinoidal ring and a "conjugated" π system. The spectral properties of these species are therefore very similar, comprising a broad charge transfer band with very little absorption to either side of it, in fact a "blue window" centred on 460 nm (fig. 2, below). As a result of their charge separated ground state, these molecules have large theoretical μβ(0) products, indicative of a high second order nonlinearity. The molecular figure of merit, μβ(0) has been calculated for I as -17,500 x 10-48esu. Three TCNQ adducts prepared by conventional reactions of TCNQ with secondary amines6 are included (IIX - X) for comparison purposes. The μβ(0) product of X has been determined7 to be -840 x 10-48 esu, assuming a calculated μ of 3.5 D. This material is however extremely insoluble and therefore difficult to work with.
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Zyss, Joseph. "From Dipolar to Multipolar Systems: Opening New Geometric and Quantum Dimensions in Molecular Nonlinear Optics." In Nonlinear Optics: Materials, Fundamentals and Applications. Washington, D.C.: Optica Publishing Group, 1996. http://dx.doi.org/10.1364/nlo.1996.nmd.1.

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The field of Molecular Nonlinear Optics1 has been seeded in the mid-seventies by the all pervading molecular diode template as exemplified by paranitroaniline derivatives exhibiting the now well recognized features of a rod-like dipolar structure with quasi-one dimensional intramolecular charge transfer between a single donor-acceptor pair via a delocalized π electron linkage. A highly consistent body of experiments in solutions, crystals and polymers as well as related models have come to reinforce the validity of this approach which has been further substantiated by a series of conceptual as well as application oriented developments. NLO measurements are now well acknowledged and currently used in Chemistry as sensitive probes of such basic features as intramolecular charge transfer or π-electron delocalization in conjugated systems whereas recent demonstrations of high bandwidth electrooptic modulation in polymer based modulators2 or low threshold near IR infrared parametric oscillation in molecular crystals3 evidence the application potential of the field. The existence of a large ground state dipole moment and the possibility to couple it to a poling electric field via a Langevin-Boltzmann distribution stands-out as the major cornerstone responsible for the development of the field. A two-level model pointing-out the difference between excited and ground state dipoles as a basic underlying parameter further strengthens the relevance of a dipolar geometry. However, such highly consistent interplay of dipolar models, experiments and technologies may have lead to ignore broader possibilities as recently recognized in the form of octupolar (see Fig.1) and more generally, multipolar systems4.
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Marcy, H. O., M. J. Rosker, Tallis Y. Chang, J. Khoury, K. Hansen, and R. L. Whetten. "Near-Resonance, Time-Resolved Degenerate Four Wave Mixing Studies for Thin Films of C60 and C70 Fullerenes Using Femtosecond Optical Pulses." In Nonlinear Optics. Washington, D.C.: Optica Publishing Group, 1992. http://dx.doi.org/10.1364/nlo.1992.ma6.

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The availability of gram-scale quantities of fullerenes allows for the study the of the physical properties of these unique molecules. The large number of highly polarizable electrons associated with fullerene molecules make them potentially attractive as nonlinear optical materials. Structural studies indicate that fullerenes are bound together in the solid state by relatively weak van der Waals forces. An enhancement of the nonlinear optical response for excitation near the band edge, similar to that observed for semiconductor clusters in passive glass matrices, may occur due to the relative isolation of the individual fullerene molecules. Recent reports1–3 indicate that C60 has a relatively large third-order nonlinear optical response at wavelengths far from the band edge -- on the order of that observed for many highly conjugated organic polymers.
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