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Articoli di riviste sul tema "Polaron delocalization"

Autore: Grafiati

Pubblicato: 21 dicembre 2024

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1

Rawson, Jeff, Paul J. Angiolillo e Michael J. Therien. "Extreme electron polaron spatial delocalization in π-conjugated materials". Proceedings of the National Academy of Sciences 112, n. 45 (28 ottobre 2015): 13779–83. http://dx.doi.org/10.1073/pnas.1512318112.

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The electron polaron, a spin-1/2 excitation, is the fundamental negative charge carrier in π-conjugated organic materials. Large polaron spatial dimensions result from weak electron-lattice coupling and thus identify materials with unusually low barriers for the charge transfer reactions that are central to electronic device applications. Here we demonstrate electron polarons in π-conjugated multiporphyrin arrays that feature vast areal delocalization. This finding is evidenced by concurrent optical and electron spin resonance measurements, coupled with electronic structure calculations that suggest atypically small reorganization energies for one-electron reduction of these materials. Because the electron polaron dimension can be linked to key performance metrics in organic photovoltaics, light-emitting diodes, and a host of other devices, these findings identify conjugated materials with exceptional optical, electronic, and spintronic properties.

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2

VASILIU-DOLOC, L., R. OSBORN, S. ROSENKRANZ, J. MESOT, J. F. MITCHELL, S. K. SINHA, O. H. SEECK, J. W. LYNN e Z. ISLAM. "POLARON ORDERING IN FERROMAGNETIC COLOSSAL MAGNETORESISTIVE OXIDES". International Journal of Modern Physics B 14, n. 29n31 (20 dicembre 2000): 3711–18. http://dx.doi.org/10.1142/s021797920000426x.

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We review our recent x-ray and neutron scattering studies that reveal static diffuse scattering due to polarons in the paramagnetic phase of the colossal magnetoresistive manganites La 2-2x Sr 1+2x Mn 2 O 7, with x=0.40 and 0.44. We show that the polarons exhibit short-range incommensurate correlations that grow with decreasing temperature, but disappear abruptly at the combined ferromagnetic and metal-insulator transition in the x=0.40 system because of the sudden charge delocalization, while persisting at low temperature in the antiferromagnetic x=0.44 system. The "melting" of the polaron ordering as we cool through TC occurs with the collapse of the polaron scattering itself in the x=0.40 system. The polaron order is characterized by an ordering wave vector q=(0.3,0,1) that is almost independent of x for x≥0.40, and is consistent with a model of disordered stripes.

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3

Ghosh, Raja, Christopher M. Pochas e Frank C. Spano. "Polaron Delocalization in Conjugated Polymer Films". Journal of Physical Chemistry C 120, n. 21 (19 maggio 2016): 11394–406. http://dx.doi.org/10.1021/acs.jpcc.6b02917.

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4

Yan, X. Z., J. Pawlas, T. Goodson e J. F. Hartwig. "Polaron Delocalization in Ladder Macromolecular Systems". Journal of the American Chemical Society 127, n. 25 (giugno 2005): 9105–16. http://dx.doi.org/10.1021/ja050184n.

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5

Matheson, Andrew B., Arvydas Ruseckas, Scott J. Pearson e Ifor D. W. Samuel. "Hole delocalization as a driving force for charge pair dissociation in organic photovoltaics". Materials Horizons 6, n. 5 (2019): 1050–56. http://dx.doi.org/10.1039/c8mh01204k.

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6

Feng, Tao, Liping Li, Quan Shi, Shengde Dong, Baoyun Li, Ke Li e Guangshe Li. "Evidence for the influence of polaron delocalization on the electrical transport in LiNi0.4+xMn0.4−xCo0.2O2". Physical Chemistry Chemical Physics 22, n. 4 (2020): 2054–60. http://dx.doi.org/10.1039/c9cp05768d.

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7

MUKHOPADHYAY, SOMA, e ASHOK CHATTERJEE. "EFFECT OF MULTIPLE PHONON BRANCHES ON THE PHASE TRANSITIONAL BEHAVIOR OF A TWO-DIMENSIONAL POLARON GAS". International Journal of Modern Physics B 09, n. 07 (30 marzo 1995): 849–57. http://dx.doi.org/10.1142/s0217979295000331.

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Using an all-coupling variational method and the random phase approximation, it is shown that a two-dimensional polaron gas exhibiting no localization-delocalization transition with a single optical phonon branch may undergo such a transition in the presence of an additional phonon branch. However, if the system already shows a transition, with a single phonon branch, then the effect of an additional branch is just to enhance the low-mobility self-trapped phase of the polaron.

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8

Steyrleuthner, Robert, Yuexing Zhang, Lei Zhang, Felix Kraffert, Benjamin P. Cherniawski, Robert Bittl, Alejandro L. Briseno, Jean-Luc Bredas e Jan Behrends. "Impact of morphology on polaron delocalization in a semicrystalline conjugated polymer". Physical Chemistry Chemical Physics 19, n. 5 (2017): 3627–39. http://dx.doi.org/10.1039/c6cp07485e.

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9

Fialko, N. S., e V. D. Lakhno. "Numerical Simulation of Small Radius Polaron in a Chain with Random Perturbations". Mathematical Biology and Bioinformatics 14, n. 1 (10 aprile 2019): 126–36. http://dx.doi.org/10.17537/2019.14.126.

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In a number of publications about biophysical experiments on the transfer of a charge to DNA, it is assumed that charge is transferred via a super-exchange mechanism at short distances of 2–3 nucleotide pairs, and in long fragments the charge forms a polaron that moves along the chain under the influence of temperature fluctuations. Using numerical simutation, we investigate the dynamics of a polaron of small radius in a homogeneous chain plaiced in constant electric field at a finite temperature. It is shown that there is no charge transfer by the polaron mechanism, i.e. there is no sequential movement of the polaron from site to site, in chains with parameter valuess corresponding to homogeneous adenine DNA fragments. The “polaron or delocalized state” check is based on the control of the average characteristics: the delocalization parameter, the position of the maximum probability, and the maximum modulus displacement. The dynamics of individual trajectories is also considered. Without electric field, there is a mode of switching between the states "stationary polaron – delocalized state", and a new polaron arises at a random site of the chain. In the chain placed in field with constant intensity, the averaged charge moves in the direction of the field, but the transfer occurs in a delocalized state.

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10

Ji, Xiaozhou, Mingwan Leng, Haomiao Xie, Chenxu Wang, Kim R. Dunbar, Yang Zou e Lei Fang. "Extraordinary electrochemical stability and extended polaron delocalization of ladder-type polyaniline-analogous polymers". Chemical Science 11, n. 47 (2020): 12737–45. http://dx.doi.org/10.1039/d0sc03348k.

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11

Quémerais, P., e S. Fratini. "Polaron Dissociation at the Insulator-to-Metal Transition". Modern Physics Letters B 11, n. 30 (30 dicembre 1997): 1303–12. http://dx.doi.org/10.1142/s0217984997001559.

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Considering the long range Coulomb interactions between large polarons in dielectrics, we propose a model for their crystallization when no bipolarons are formed. As the density increases, the melting is examined at T=0 K. One possibility is the delocalization towards a liquid state of polarons. However, we show that this cannot happen if the electron-phonon coupling is larger than some critical value. The other competing mechanism is the dissociation of the polarons themselves, favored owing to their large mass at strong coupling. Finally, we propose a phase diagram for the insulator-to-metal transition as a function of the density and electron–phonon coupling.

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12

Ghosh, Raja, Christine K. Luscombe, Mike Hambsch, Stefan C. B. Mannsfeld, Alberto Salleo e Frank C. Spano. "Anisotropic Polaron Delocalization in Conjugated Homopolymers and Donor–Acceptor Copolymers". Chemistry of Materials 31, n. 17 (12 luglio 2019): 7033–45. http://dx.doi.org/10.1021/acs.chemmater.9b01704.

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13

Susumu, Kimihiro, Paul R. Frail, Paul J. Angiolillo e Michael J. Therien. "Conjugated Chromophore Arrays with Unusually Large Hole Polaron Delocalization Lengths". Journal of the American Chemical Society 128, n. 26 (luglio 2006): 8380–81. http://dx.doi.org/10.1021/ja0614823.

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14

Niklas, Jens, Tianyue Zheng, Andriy Neshchadin, Kristy L. Mardis, Luping Yu e Oleg G. Poluektov. "Polaron and Exciton Delocalization in Oligomers of High-Performance Polymer PTB7". Journal of the American Chemical Society 142, n. 3 (20 dicembre 2019): 1359–66. http://dx.doi.org/10.1021/jacs.9b10859.

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15

Rosso, Kevin, Christian Ahart, Guido Falk von Rudorff e Jochen Blumberger. "(Invited) Polaronic Transport in Iron Oxides from Density Functional Theory". ECS Meeting Abstracts MA2022-02, n. 48 (9 ottobre 2022): 1840. http://dx.doi.org/10.1149/ma2022-02481840mtgabs.

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Iron oxides such as hematite (α-Fe2O3) play an important role in diverse fields ranging from biogeochemistry to photocatalysis. In the majority of these cases their electrical properties are key because they facilitate electron transfer reactions occurring at their interfaces. The iron oxides tend to be wide band gap semiconductors with a narrow d band. Consequently, electron and hole charge carriers localize by self-trapping to form polarons, carriers whose mobilities are tied to the lattice distortions they create. Site-to-site polaron transport is thermally activated and the rate depends on the energy to reorganize the local structure into a suitable transition state, as well as the strength of the electronic coupling in that transient configuration. In turn, these depend on factors that determine the atomic and electronic structure, including crystallographic direction. Because the structure of polarons, the reorganization energy, and the electronic coupling matrix element are not readily experimentally accessible, quantum mechanical calculations have been extraordinarily useful. However, this also means that the accuracy of predicting polaronic charge carrier mobilities depends strongly on the computational method used. In the ~20 years since the first application of ab initio cluster model computations to this topic for hematite, both the methodological rigor and the supporting computational power have greatly advanced. After a brief historical overview, this talk will highlight current findings obtained with gap-optimized hybrid density functional theory with periodic boundary conditions performed on massively parallel supercomputers. Comparisons will be made to the original calculations for hematite published in 2003. The DFT-based predictions for other iron oxide phases will also be discussed. Specifically, we will present calculations of both the electron and hole polaron structures and associated reorganization energies for the bulk of hematite, lepidocrocite (γ-FeOOH), goethite (α-FeOOH) and white rust (Fe(OH)2).1 Through the use of gap-optimized hybrid functionals and large supercells under periodic boundary conditions, we remove some of the complications and uncertainties present in earlier cluster model calculations. It is found that while the hole polaron in these materials generally localizes onto a single iron site, the electron polaron delocalizes across two iron sites of the same spin layer as a consequence of the lower reorganization energy for electrons compared to holes. An exception to these trends is the hole of goethite, which according to our calculations does not form a localized polaron. For hematite,2 we find that upon ionization the hole relaxes from a delocalized band state to a polaron localized on a single iron atom with localization induced by tetragonal distortion of the six surrounding iron-oxygen bonds. This distortion is responsible for sluggish hopping transport in the Fe-bilayer, characterized by an activation energy of 70 meV and a hole mobility of 0.031 cm2/(V s). By contrast, the excess electron induces a smaller distortion of the iron-oxygen bonds resulting in delocalization over two neighboring Fe units. We find that 2-site delocalization is advantageous for charge transport due to the larger spatial displacements per transfer step. As a result, the electron mobility is predicted to be a factor of three higher than the hole mobility, 0.098 cm2/(V s), in qualitative agreement with experimental observations. The advances made on the theory and simulation front have provided increasing insight into the nature of polaronic transport in the iron oxides, and the methods have been widely duplicated successfully to a variety of materials. However, there is tremendous room for expansion of the work to treat the more challenging aspects governing iron oxide behavior in natural systems and in device application, including the role of interfaces, surface potential, and defects to name a few. Theoretical computations seem poised now more than ever to help unlock the fundamental insight into charge carrier transport in polaronic materials needed to understand and adapt their electrical transport properties. References Ahart C.S., Blumberger J., Rosso K.M. (2020) Polaronic structure of excess electrons and holes for a series of bulk iron oxides. Physical Chemistry Chemical Physics, 22, 10699-10709. Ahart C.S., Rosso K.M., Blumberger J. (2022) Electron and hole mobilities in bulk hematite from spin-constrained density functional theory. Journal of the American Chemical Society, 144, 4623-4632.

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16

Stanfield, Dane A., Zerina Mehmedović e Benjamin J. Schwartz. "Vibrational Stark Effect Mapping of Polaron Delocalization in Chemically Doped Conjugated Polymers". Chemistry of Materials 33, n. 21 (26 ottobre 2021): 8489–500. http://dx.doi.org/10.1021/acs.chemmater.1c02934.

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17

Amaya, Toru, Yasushi Abe e Toshikazu Hirao. "Deprotonation-Induced Efficient Delocalization of Polaron in Self-Doped Poly(anilinephosphonic acid)". Macromolecules 47, n. 22 (10 novembre 2014): 8115–18. http://dx.doi.org/10.1021/ma5016209.

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18

Shirasaki, Ryōen, e Kaoru Iwano. "Delocalization of Polaron of the Extended Peierls–Hubbard System in the Mott Phase". Journal of the Physical Society of Japan 72, n. 11 (15 novembre 2003): 2902–7. http://dx.doi.org/10.1143/jpsj.72.2902.

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19

Dexter Tam, Teck Lip, Akshay Moudgil, Wei Jie Teh, Zicong Marvin Wong, Albertus Denny Handoko, Sheau Wei Chien, Shuo-Wang Yang, Boon Siang Yeo, Wei Lin Leong e Jianwei Xu. "Polaron Delocalization Dependence of the Conductivity and the Seebeck Coefficient in Doped Conjugated Polymers". Journal of Physical Chemistry B 126, n. 9 (24 febbraio 2022): 2073–85. http://dx.doi.org/10.1021/acs.jpcb.2c00303.

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20

Ivanov, Maxim V., Ruchi Shukla, Sergey V. Lindeman, Denan Wang e Rajendra Rathore. "Pyrene-Like HOMO Governs Polaron Delocalization in Model Graphitic Strips: A Combined Experimental and Computational Analysis". Journal of Physical Chemistry C 122, n. 43 (9 ottobre 2018): 24527–34. http://dx.doi.org/10.1021/acs.jpcc.8b06068.

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21

Park, Kyu Hyung, Sung Yun Son, Jun Oh Kim, Gyeongho Kang, Taiho Park e Dongho Kim. "Role of Disorder in the Extent of Interchain Delocalization and Polaron Generation in Polythiophene Crystalline Domains". Journal of Physical Chemistry Letters 9, n. 12 (25 maggio 2018): 3173–80. http://dx.doi.org/10.1021/acs.jpclett.8b01050.

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22

Niklas, Jens, Kristy L. Mardis, Brian P. Banks, Gregory M. Grooms, Andreas Sperlich, Vladimir Dyakonov, Serge Beaupré et al. "Highly-efficient charge separation and polaron delocalization in polymer–fullerene bulk-heterojunctions: a comparative multi-frequency EPR and DFT study". Physical Chemistry Chemical Physics 15, n. 24 (2013): 9562. http://dx.doi.org/10.1039/c3cp51477c.

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23

da Silva, Jéssica Montenegro Santana, Adriano de Souza Carolino, Lilian Rodrigues de Oliveira, Douglas de Souza Gonçalves, Matheus Moraes Biondo, Pedro Henrique Campelo, Jaqueline de Araújo Bezerra et al. "Poly(o-methoxyaniline) Chain Degradation Based on a Heat Treatment (HT) Process: Combined Experimental and Theoretical Evaluation". Molecules 27, n. 12 (8 giugno 2022): 3693. http://dx.doi.org/10.3390/molecules27123693.

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Poly(o-methoxyaniline) emeraldine-salt form (ES-POMA) was chemically synthesized using hydrochloric acid and subjected to a heat treatment (HT) process for 1 h at 100 °C (TT100) and 200 °C (TT200). The HT process promoted a progressive decrease in crystallinity. The Le Bail method revealed a decomposition from tetrameric to trimeric-folded chains after the HT process. The unheated POMA-ES presented a globular vesicular morphology with varied micrometric sizes. The heat treatment promoted a reduction in these globular structures, increasing the non-crystalline phase. The boundary length (S) and connectivity/Euler feature (χ) parameters were calculated from the SEM images, revealing that ES-POMA presented a wide distribution of heights. The TT100 and TT200 presented a narrow boundary distribution, suggesting smoother surfaces with smaller height variations. The UV-VIS analysis revealed that the transition at 343 nm (nonlocal π → π*) was more intense in the TT200 due to the electronic delocalization, which resulted from the reduced polymer chain caused by the HT process. In addition to the loss of conjugation, counter ion withdrawal reduced the ion-chain interaction, decreasing the local electron density. This result shows the influence of the chlorine counter ions on the peaks position related to the HOMO → LUMO transition, since the π → polaron transition occurs due to the creation of the energy states due to the presence of counter ions. Finally, the electrical conductivity decreased after the HT process from 1.4 × 10−4 S.cm−1 to 2.4 × 10−6 S.cm−1 as result of the polymer deprotonation/degradation. Thus, this paper proposed a systematic evaluation of the POMA molecular structure and crystallite size and shape after heat treatment.

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24

Tamai, Yasunari, Kazuki Tsuda, Hideo Ohkita, Hiroaki Benten e Shinzaburo Ito. "Charge-carrier generation in organic solar cells using crystalline donor polymers". Phys. Chem. Chem. Phys. 16, n. 38 (2014): 20338–46. http://dx.doi.org/10.1039/c4cp01820f.

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25

Capobianco, Amedeo, Tonino Caruso e Andrea Peluso. "Hole delocalization over adenine tracts in single stranded DNA oligonucleotides". Physical Chemistry Chemical Physics 17, n. 6 (2015): 4750–56. http://dx.doi.org/10.1039/c4cp04282d.

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26

Larionov, A. V., A. S. Brichkin, S. Hofling e V. D. Kulakovskii. "Localization-delocalization transition in disordered one-dimensional exciton-polariton system". Физика и техника полупроводников 52, n. 4 (2018): 468. http://dx.doi.org/10.21883/ftp.2018.04.45817.06.

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AbstractThe transition from the delocalized to the localized state has been investigated in a quasi-onedimensional exciton-polariton system excited nonresonantly in GaAs-based microcavity wire with disordered potential. The photoexcited polariton condensate has been found to spread along the wire with а velocity exceeding 1 μm/ps. The propagation along the wire is provided by high energy polaritons. The LP localization length decreases with decreasing blue shift of LPs in the excited spot. The polariton condensate returns to the Bose glass state when the blue shift of the LP resonance at the excitation spot decreases below the critical level that depends on the potential disorder.

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27

Xiang, Bo, Raphael F. Ribeiro, Yingmin Li, Adam D. Dunkelberger, Blake B. Simpkins, Joel Yuen-Zhou e Wei Xiong. "Manipulating optical nonlinearities of molecular polaritons by delocalization". Science Advances 5, n. 9 (settembre 2019): eaax5196. http://dx.doi.org/10.1126/sciadv.aax5196.

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Optical nonlinearities are key resources in the contemporary photonics toolbox, relevant to quantum gate operations and all-optical switches. Chemical modification is often used to control the nonlinear response of materials at the microscopic level, but on-the-fly manipulation of such response is challenging. Tunability of optical nonlinearities in the mid-infrared (IR) is even less developed, hindering its applications in chemical sensing or IR photonic circuitry. Here, we report control of vibrational polariton coherent nonlinearities by manipulation of macroscopic parameters such as cavity longitudinal length or molecular concentration. Further two-dimensional IR investigations reveal that nonlinear dephasing provides the dominant source of the observed ultrafast polariton nonlinearities. The reported phenomena originate from the nonlinear macroscopic polarization stemming from strong coupling between microscopic molecular excitations and a macroscopic photonic cavity mode.

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Khalil, Hanaa, e Kalle Levon. "Shear-Induced Delocalization of Polarons in Polyaniline−Surfactant Complexes". Macromolecules 35, n. 21 (ottobre 2002): 8180–84. http://dx.doi.org/10.1021/ma020146d.

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Acquarone, M. "Doping dependence of the delocalization energy of spin polarons". Physica B: Condensed Matter 259-261 (gennaio 1999): 509–10. http://dx.doi.org/10.1016/s0921-4526(98)00913-2.

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Krinichny, V. I. "Spin-Dependent Regulation of The Electronic and Magnetic Properties of Poly(3-Alkylthiophene) Oligomers and Their Composites with Aromatic Nanoadditives". Himiâ vysokih ènergij 58, n. 3 (25 ottobre 2024): 175–89. http://dx.doi.org/10.31857/s0023119324030014.

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The energy and spin parameters of poly(3-alkylthiophene) oligomers and their composites with aromatic hydrocarbons are calculated. The coexistence of polarons with different degrees of delocalization in the studied compounds has been identified. Periodic changes in the electronic and spin properties of composites were detected, initiated by the interaction of oligomers with aromatic nanoadditives. The anisotropic parameters of the spin Hamiltonians of the studied systems are obtained and their high-resolution EPR spectra are calculated.

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Levon, Kalle, e Hanaa Khalil. "Shear-induced delocalization of polarons in polyaniline-zinc salt complexes". Macromolecular Symposia 156, n. 1 (luglio 2000): 103–8. http://dx.doi.org/10.1002/1521-3900(200007)156:1<103::aid-masy103>3.0.co;2-m.

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Österbacka, Nicklas, Paul Erhart, Stefano Falletta, Alfredo Pasquarello e Julia Wiktor. "Small Electron Polarons in CsPbBr3: Competition between Electron Localization and Delocalization". Chemistry of Materials 32, n. 19 (23 settembre 2020): 8393–400. http://dx.doi.org/10.1021/acs.chemmater.0c02345.

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Zhang, W., A. O. Govorov e S. E. Ulloa. "Delocalization of Wannier-Stark ladders by phonons: Tunneling and stretched polarons". Europhysics Letters (EPL) 58, n. 6 (giugno 2002): 857–63. http://dx.doi.org/10.1209/epl/i2002-00453-y.

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Dimitriev, O. P. "The exciton size. Where are the limits?" Semiconductor Physics, Quantum Electronics and Optoelectronics 25, n. 4 (22 dicembre 2022): 372–78. http://dx.doi.org/10.15407/spqeo25.04.372.

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The concept of exciton implies a collective excited state able to travel in a particle-like fashion. Its size is determined by the radius of excited electron-hole pair and, although it may vary by two orders of magnitude, it is always spatially restricted, while its delocalization length owing to the exciton wavefunction spatial dynamics may provide even a larger scale of changes. In this work, the limitations of exciton sizes are discussed by analysis where the exciton concept is still applicable. It is shown that the exciton size can be as small as few angstroms, but even smaller sizes can be, probably, justified. At the same time, coupling of exciton to polariton mode can enlarge the exciton-polariton coherence length to values as high as 20 µm, thus extending the scale of possible exciton sizes up to five orders of magnitude.

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Larionov, A. V., A. S. Brichkin, S. Höfling e V. D. Kulakovskii. "Localization-Delocalization Transition in Disordered One-Dimensional Exciton-Polariton System". Semiconductors 52, n. 4 (aprile 2018): 458–61. http://dx.doi.org/10.1134/s106378261804019x.

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Zakhidov, A. A., G. T. Zhamanbayeva e G. Sh Yar-Mukhamedova. "Investigation of degradation processes in perovskite under the influence of external factors". Kompleksnoe Ispolʹzovanie Mineralʹnogo syrʹâ/Complex Use of Mineral Resources/Mineraldik Shikisattardy Keshendi Paidalanu 3, n. 319 (28 ottobre 2021): 19–24. http://dx.doi.org/10.31643/2021/6445.36.

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The article describes a number of new fundamental knowledge about mechanisms of degradation processes occurring in photoactive perovskite materials based on complex lead halides and solar cells based on them, modern methods and approaches to increasing the operational stability of perovskite photovoltaic devices are considered. The revealed paths of degradation processes occurring in complex metal halides (lead and tin) under the influence of light and elevated temperatures are important for further developments in the field of creating highly efficient and stable perovskite solar cells of a new generation. The investigated models of degradation are described both under the action of moisture and as a result of radiation ionization processes. The importance of solving the Dexter-Varley paradox, which takes into account the competition between the processes of displacement of IS0 states, as well as the delocalization of the resulting hole in the valence band, is emphasized. It was shown that by changing the force of pressure of the tape on the perovskite film, it was possible to achieve the maximum values of the light conversion efficiency of about 12.7%. It was found that the presence of charge carriers in the form of polarons can significantly affect the assessment of the degradation efficiency towards its increase. The data obtained can radically change the traditional ideas about the efficiency of photochemical reactions.

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Takeda, Norihiko, e John R. Miller. "Poly(3-decylthiophene) Radical Anions and Cations in Solution: Single and Multiple Polarons and Their Delocalization Lengths in Conjugated Polymers". Journal of Physical Chemistry B 116, n. 50 (6 dicembre 2012): 14715–23. http://dx.doi.org/10.1021/jp3096242.

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Wu, Weijun, Andrew E. Sifain, Courtney A. Delpo e Gregory D. Scholes. "Polariton enhanced free charge carrier generation in donor–acceptor cavity systems by a second-hybridization mechanism". Journal of Chemical Physics 157, n. 16 (28 ottobre 2022): 161102. http://dx.doi.org/10.1063/5.0122497.

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Cavity quantum electrodynamics has been studied as a potential approach to modify free charge carrier generation in donor–acceptor heterojunctions because of the delocalization and controllable energy level properties of hybridized light–matter states known as polaritons. However, in many experimental systems, cavity coupling decreases charge separation. Here, we theoretically study the quantum dynamics of a coherent and dissipative donor–acceptor cavity system, to investigate the dynamical mechanism and further discover the conditions under which polaritons may enhance free charge carrier generation. We use open quantum system methods based on single-pulse pumping to find that polaritons have the potential to connect excitonic states and charge separated states, further enhancing free charge generation on an ultrafast timescale of several hundred femtoseconds. The mechanism involves polaritons with optimal energy levels that allow the exciton to overcome the high Coulomb barrier induced by electron–hole attraction. Moreover, we propose that a second-hybridization between a polariton state and dark states with similar energy enables the formation of the hybrid charge separated states that are optically active. These two mechanisms lead to a maximum of 50% enhancement of free charge carrier generation on a short timescale. However, our simulation reveals that on the longer timescale of picoseconds, internal conversion and cavity loss dominate and suppress free charge carrier generation, reproducing the experimental results. Thus, our work shows that polaritons can affect the charge separation mechanism and promote free charge carrier generation efficiency, but predominantly on a short timescale after photoexcitation.

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39

Poznanski, Roman R., Jalil Ali, Nicolangelo L. Iannella e Valeriy Sbitnev. "Consciousness: a quantum optical effect in fluorescent protein pathways". Journal of Multiscale Neuroscience 3, n. 3 (16 settembre 2024): 224–41. http://dx.doi.org/10.56280/1648335153.

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This paper presents a physical mechanism of embodied consciousness based on the dynamic organicity theory. We use the entropic pilot wave theory to describe the quantum dipole oscillations from dipole-bound delocalized (quasi-free) electrons in nonpolar nanocavities of aromatic amino acid residues (benzene moiety /cyclic hydrocarbons that contain resonance structures) and their fluorescent pathways. These pathways contain cavity quasipolariton condensates composed of quantized polarization waves of entangled photons. The behavior of oscillating molecular dipoles is influenced by the quantum nature of dynamic organicity, which causes energy fluctuations necessary to move delocalized electrons and create bare polaritons (quantized polarization waves). These waves correspond to photon quasiparticles interacting with water molecules to form quasipolaritons, softened by interacting with hydroxide ions (OH-) within crystal lattices of interfacial water H30. When [H3O+]=[OH−], the solution is neutral in hydrophobic nanocavities. In such nonpolar cavities, evanescent photons (non-radiative transitions in the absence of any source) are emitted while protons (H+) diffuse due to recombination with hydroxide (OH-) ions, acting as protonic analogs of ‘holes’ or excitons. In protein pores, proton motion strongly coupled with π-electron delocalization is a conduit for exciton-photon (polariton) and its polarization wave component. Internal energy fluctuations comprise both quantum potential energy and negative quantum kinetic energy. We explore how quantum potential energy influences the negentropic effect of a 'repulsive force' guided by entropic pilot waves through pilot wave force (negentropic force), functioning as an information-based action of the polarization wave as a conduit of the cavity quasipolariton. When the rate of change of quantum entropy is zero, and momentum of the polarization wave is zero the internal energy transduction between quantum potential energy to quantum kinetic energy manifests as the negentropic force and facilitates the movement of information-based action for information encoding when negative quantum kinetic energy happens at certain times. Experiments have shown that biphoton entanglement interferes with anaesthetics. We postulate that the disruption of cavity polaritonic condensate through its polarization wave component disrupts the decoding of information, suggesting consciousness is attributed to a quantum optical effect. Therefore, we further theorize that consciousness is attributed to the negative quantum kinetic energy of the polarization wave, which provides an informational structure of multiscale redundancy when negentropic action reduces information redundancy. This has profound implications for understanding consciousness as nonmechanical action channeled through negentropic force when the rate of change of quantum entropy is zero.

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40

Giri, Dipanjan, Shraman Kumar Saha, Iona Anderson, Amit Chakraborty, Jyotsana Kala, Jolanda Simone Müller, Jenny Nelson, Ram Kumar Canjeevaram Balasubramanyam e Satish Patil. "Delocalized Polarons in Diketopyrrolopyrrole‐Based Conjugated Polymers: Implications for Near‐Infrared Electrochromism and Beyond". Advanced Functional Materials, 12 novembre 2024. http://dx.doi.org/10.1002/adfm.202410815.

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AbstractConjugated polymers with delocalized polarons and near‐infrared (IR) absorption properties are promising materials for applications in electrochemical devices. However, the poor stability of low bandgap polymers in electrochemical redox conditions limits the realization of such devices. Herein, a new family of near‐IR absorbing conjugated polymers based on diketopyrrolopyrrole (DPP) derivatives with methoxy substituents to achieve reversible p‐type electrochemical doping with bistable near‐IR electrochromism is designed. The extent of volumetric doping in various electrolytes using cyclic voltammetry and spectroelectrochemistry for optimal electrochemical kinetics and near‐IR contrast is systematically investigated. Further, the spray‐coated films of polymers display high open circuit memory as the methoxylation is increased on the polymer backbone. The contrasting electrochromic memory and kinetics observed for these polymers are mainly ascribed to two factors; i) the effect of backbone structure on the spatial extent of polaron delocalization, and ii) the ionization energy of the polymers. The utility of DPP‐based polymers as energy‐efficient electrochromic optical attenuators (EVOAs) with high near‐IR coloration efficiencies, and an optical attenuation value of 5.1 dB at 1.3 and 1.5 µm wavelengths is demonstrated. Furthermore, the experimental findings are corroborated with theoretical studies to establish that the polaron delocalization length is central to the performance of the device.

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41

Kopp, Sebastian M., Jie-Ren Deng, Ashley J. Redman, Henrik Gotfredsen, Robert M. J. Jacobs, Harry L. Anderson e Christiane R. Timmel. "Cationic polaron delocalization in porphyrin nanoribbons". Chem, agosto 2024. http://dx.doi.org/10.1016/j.chempr.2024.07.011.

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42

Balzer, Daniel, e Ivan Kassal. "Even a little delocalization produces large kinetic enhancements of charge-separation efficiency in organic photovoltaics". Science Advances 8, n. 32 (12 agosto 2022). http://dx.doi.org/10.1126/sciadv.abl9692.

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In organic photovoltaics, charges can separate efficiently even if their Coulomb attraction is an order of magnitude greater than the available thermal energy. Delocalization has been suggested to explain this fact, because it could increase the initial separation of charges in the charge-transfer (CT) state, reducing their attraction. However, understanding the mechanism requires a kinetic model of delocalized charge separation, which has proven difficult because it involves tracking the correlated quantum-mechanical motion of the electron and the hole in large simulation boxes required for disordered materials. Here, we report the first three-dimensional simulations of charge-separation dynamics in the presence of disorder, delocalization, and polaron formation, finding that even slight delocalization, across less than two molecules, can substantially enhance the charge-separation efficiency, even starting with thermalized CT states. Delocalization does not enhance efficiency by reducing the Coulomb attraction; instead, the enhancement is a kinetic effect produced by the increased overlap of electronic states.

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43

Mishchenko, A. S., N. Nagaosa, A. Alvermann, H. Fehske, G. De Filippis, V. Cataudella e O. P. Sushkov. "Localization-delocalization transition of a polaron near an impurity". Physical Review B 79, n. 18 (11 maggio 2009). http://dx.doi.org/10.1103/physrevb.79.180301.

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44

Thorley, Karl J. "Estimation of Polaron Delocalization Lengths in Conjugated Organic Polymers". Journal of Physical Chemistry B, 23 maggio 2023. http://dx.doi.org/10.1021/acs.jpcb.3c00153.

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45

Nishida, Jun, Peter T. S. Chang, Jiselle Y. Ye, Prachi Sharma, Dylan M. Wharton, Samuel C. Johnson, Sean E. Shaheen e Markus B. Raschke. "Nanoscale heterogeneity of ultrafast many-body carrier dynamics in triple cation perovskites". Nature Communications 13, n. 1 (3 novembre 2022). http://dx.doi.org/10.1038/s41467-022-33935-0.

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AbstractIn high fluence applications of lead halide perovskites for light-emitting diodes and lasers, multi-polaron interactions and associated Auger recombination limit the device performance. However, the relationship of the ultrafast and strongly lattice coupled carrier dynamics to nanoscale heterogeneities has remained elusive. Here, in ultrafast visible-pump infrared-probe nano-imaging of the photoinduced carrier dynamics in triple cation perovskite films, a ~20 % variation in sub-ns relaxation dynamics with spatial disorder on tens to hundreds of nanometer is resolved. We attribute the non-uniform relaxation dynamics to the heterogeneous evolution of polaron delocalization and increasing scattering time. The initial high-density excitation results in faster relaxation due to strong many-body interactions, followed by extended carrier lifetimes at lower densities. These results point towards the missing link between the optoelectronic heterogeneity and associated carrier dynamics to guide synthesis and device engineering for improved perovskites device performance.

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46

Barford, William. "Exciton dynamics in conjugated polymer systems". Frontiers in Physics 10 (12 ottobre 2022). http://dx.doi.org/10.3389/fphy.2022.1004042.

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Exciton dynamics in π-conjugated polymers systems encompass multiple time and length scales. Ultrafast femtosecond processes are intrachain and involve a quantum mechanical correlation of the exciton and nuclear degrees of freedom. In contrast, post-picosecond processes involve the incoherent Förster transfer of excitons between polymer chains. Exciton dynamics is also strongly determined by the spatial and temporal disorder that is ubiquitous in conjugated polymers. Since excitons are delocalized over hundreds of atoms, a theoretical understanding of these processes is only realistically possible by employing suitably parametrized coarse-grained exciton-phonon models. Moreover, to correctly account for ultrafast processes, the exciton and phonon modes must be treated on the same quantum mechanical basis and the Ehrenfest approximation must be abandoned. This further implies that sophisticated numerical techniques must be employed to solve these models. This review describes our current theoretical understanding of exciton dynamics in conjugated polymer systems. We begin by describing the energetic and spatial distribution of excitons in disordered polymer systems, and define the crucial concept of a “chromophore” in conjugated polymers. We also discuss the role of exciton-nuclear coupling, emphasizing the distinction between “fast” and “slow” nuclear degrees of freedom in determining “self-trapping” and “self-localization” of exciton-polarons. Next, we discuss ultrafast intrachain exciton decoherence caused by exciton-phonon entanglement, which leads to fluorescence depolarization on the timescale of 10-fs. Interactions of the polymer with its environment causes the stochastic relaxation and localization of high-energy delocalized excitons onto chromophores. The coupling of excitons with torsional modes also leads to various dynamical processes. On sub-ps timescales it causes exciton-polaron formation (i.e., exciton localization and local polymer planarization). Conversely, on post-ps timescales stochastic torsional fluctuations cause exciton-polaron diffusion along the polymer chain and at higher temperatures to transient exciton delocalization via extended exciton states. We next describe a first-principles, Förster-type model of interchain exciton transfer and diffusion in the condensed phase, whose starting point is a realistic description of the donor and acceptor chromophores. Finally, we discuss condensed phase transient exciton delocalization in highly-ordered nanofibers. We survey experimental results and explain how they can be understood in terms of our theoretical description of exciton dynamics coupled to information on polymer multiscale structures. The review also contains a brief critique of computational methods to simulate exciton dynamics.

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47

Reppert, Mike, Rajesh Dutta e Lyudmila Slipchenko. "The interplay of excitonic delocalization and vibrational localization in optical lineshapes: A variational polaron approach". Journal of Chemical Physics 161, n. 15 (18 ottobre 2024). http://dx.doi.org/10.1063/5.0225083.

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The dynamics of molecular excitonic systems are complicated by a competition between electronic coupling (which drives delocalization) and vibrational-electronic (vibronic) interactions (which tend to encourage electronic localization). A particular challenge of molecular systems is that they typically possess a large number of independent vibrations, with frequencies often spanning the entire spectrum of relevant electronic energy gaps. Recent spectroscopic observations and numerical simulations on a water-soluble chlorophyll-binding protein (WSCP) reveal a transition between two regimes of vibronic behavior, a Redfield-like regime in which low-frequency vibrations respond to a delocalized excitonic state, and a Förster-like regime where high-frequency vibrations act as incoherent excitations on individual pigments. Although numerical simulations can reproduce these effects, there is a need for a simple, systematic theory that accurately describes the smooth transition between these two regimes in experimental spectra. Here we address this challenge by generalizing the variational polaron transform approach of [Bloemsma et al., Chem. Phys. 481, 250 (2016)] to include arbitrary bath densities for systems with or without symmetry. We benchmark this theory against both numerical matrix-diagonalization methods and experimental 77 K fluorescence spectra for two WSCP variants, obtaining quite satisfactory agreement in both cases. We apply this theory to offer an explanation for the large loss in apparent electronic coupling in the WSCP Q57K mutant and to examine the likely impact of the interplay between excitonic delocalization and vibrational localization on vibrational sideband shapes and apparent coupling strengths in high-resolution optical spectra for chlorophyll-protein complexes such as WSCP.

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48

Moser, Maximilian, Achilleas Savva, Karl Thorley, Bryan D. Paulsen, Tania Cecilia Hidalgo, David Ohayon, Hu Chen et al. "Polaron Delocalization in Donor‐Acceptor Polymers and its Impact on Organic Electrochemical Transistor Performance". Angewandte Chemie International Edition, dicembre 2020. http://dx.doi.org/10.1002/anie.202014078.

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49

Moser, Maximilian, Achilleas Savva, Karl Thorley, Bryan D. Paulsen, Tania Cecilia Hidalgo, David Ohayon, Hu Chen et al. "Polaron Delocalization in Donor‐Acceptor Polymers and its Impact on Organic Electrochemical Transistor Performance". Angewandte Chemie, dicembre 2020. http://dx.doi.org/10.1002/ange.202014078.

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50

Chang, Jui-Fen, Jenny Clark, Ni Zhao, Henning Sirringhaus, Dag W. Breiby, Jens W. Andreasen, Martin M. Nielsen, Mark Giles, Martin Heeney e Iain McCulloch. "Molecular-weight dependence of interchain polaron delocalization and exciton bandwidth in high-mobility conjugated polymers". Physical Review B 74, n. 11 (21 settembre 2006). http://dx.doi.org/10.1103/physrevb.74.115318.

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