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Journal articles on the topic 'Exciton dynamic'

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Author: Grafiati

Published: 1 April 2023

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1

Tao, Weijian, Qiaohui Zhou, and Haiming Zhu. "Dynamic polaronic screening for anomalous exciton spin relaxation in two-dimensional lead halide perovskites." Science Advances 6, no. 47 (November 2020): eabb7132. http://dx.doi.org/10.1126/sciadv.abb7132.

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Two-dimensional lead halide perovskites with confined excitons have shown exciting potentials in optoelectronic applications. It is intriguing but unclear how the soft and polar lattice redefines excitons in layered perovskites. Here, we reveal the intrinsic exciton properties by investigating exciton spin dynamics, which provides a sensitive probe to exciton coulomb interactions. Compared to transition metal dichalcogenides with comparable exciton binding energy, we observe orders of magnitude smaller exciton-exciton interaction and, counterintuitively, longer exciton spin lifetime at higher temperature. The anomalous spin dynamics implies that excitons exist as exciton polarons with substantially weakened inter- and intra-excitonic interactions by dynamic polaronic screening. The combination of strong light matter interaction from reduced dielectric screening and weakened inter-/intra-exciton interaction from dynamic polaronic screening explains their exceptional performance and provides new rules for quantum-confined optoelectronic and spintronic systems.

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2

Sneyd, Alexander J., Tomoya Fukui, David Paleček, Suryoday Prodhan, Isabella Wagner, Yifan Zhang, Jooyoung Sung, et al. "Efficient energy transport in an organic semiconductor mediated by transient exciton delocalization." Science Advances 7, no. 32 (August 2021): eabh4232. http://dx.doi.org/10.1126/sciadv.abh4232.

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Efficient energy transport is desirable in organic semiconductor (OSC) devices. However, photogenerated excitons in OSC films mostly occupy highly localized states, limiting exciton diffusion coefficients to below ~10−2 cm2/s and diffusion lengths below ~50 nm. We use ultrafast optical microscopy and nonadiabatic molecular dynamics simulations to study well-ordered poly(3-hexylthiophene) nanofiber films prepared using living crystallization-driven self-assembly, and reveal a highly efficient energy transport regime: transient exciton delocalization, where energy exchange with vibrational modes allows excitons to temporarily re-access spatially extended states under equilibrium conditions. We show that this enables exciton diffusion constants up to 1.1 ± 0.1 cm2/s and diffusion lengths of 300 ± 50 nm. Our results reveal the dynamic interplay between localized and delocalized exciton configurations at equilibrium conditions, calling for a re-evaluation of exciton dynamics and suggesting design rules to engineer efficient energy transport in OSC device architectures not based on restrictive bulk heterojunctions.

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3

Chaouachi, Nizar, and Sihem Jaziri. "Possibility of observation quantum beat coherent exciton states with time-resolved photoemission." Journal of Applied Physics 131, no. 15 (April 21, 2022): 155704. http://dx.doi.org/10.1063/5.0086440.

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We develop a theoretical study to evaluate the dynamic of the time-resolved photoemission spectrum arising from the dissociation of exciton steady-states 1s, 2s in a monolayer transition metal dichlacogenides. We discuss the dielectric environment effect on the exciton binding energies. Quantum beat signatures in photoemission intensity demonstrate coherent coupling between 1s and 2s excitons. The beating contribution due to excitonic coherence is also discussed. The periodic oscillations arising from coherent superposition states and quantum beats enable exploration of novel coherent phenomena.

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4

Aslan, Burak, Colin Yule, Yifei Yu, Yan Joe Lee, Tony F. Heinz, Linyou Cao, and Mark L. Brongersma. "Excitons in strained and suspended monolayer WSe₂." 2D Materials 9, no. 1 (October 21, 2021): 015002. http://dx.doi.org/10.1088/2053-1583/ac2d15.

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Abstract We study suspended membranes of atomically thin WSe2 as hosts of excitons. We perform optical reflectance measurements to probe the exciton physics and obtain the peak energies for the 1 s , 2 s , and 3 s states of the A exciton in suspended WSe2 and consider supported membranes as a reference. We find that elimination of the influence of the dielectric environment enables a strong electron–hole interaction and a concomitant increase in the exciton binding energy in suspended monolayer (1L) WSe2. Based on the experimental results, we calculate the excitonic binding energies by employing the recently developed quantum electrostatic heterostructure model and the commonly employed Rytova–Keldysh potential model. We see that the binding energy of the ground state A exciton increases from about 0.3 eV (on a substrate) to above 0.4 eV (suspended). We also exploit the tunability of the excitons in suspended samples via mechanical strain. By applying external gas pressure of 2.72 atm to a 1L suspended over a circular hole of 8 μm diameter, we strain the WSe2 and obtain a reversible 0.15 eV redshift in the exciton resonance. The linewidth of the A exciton decreases by more than half, from about 50 to 20 meV under 1.5% biaxial strain at room temperature. This line narrowing is due to the suppression of intervalley exciton–phonon scattering. By making use of the observed strain-dependent optical signatures, we infer the two-dimensional (2D) elastic moduli of 1L and 2L WSe2. Our results exemplify the use of suspended 2D materials as novel systems for fundamental studies, as well as for strong and dynamic tuning of their optical properties.

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5

Uratani, Hiroki. "(Invited) Simulating Dynamic Excitons Via Quantum Molecular Dynamics: A Case Study in Lead Halide Perovskites." ECS Meeting Abstracts MA2022-01, no. 13 (July 7, 2022): 904. http://dx.doi.org/10.1149/ma2022-0113904mtgabs.

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The ultrafast electronic and structural dynamics invoked by photoexcitation, i.e., “dynamic exciton” phenomena, not only are important in the context of practical applications such as solar cells, but also raise many questions from the viewpoint of fundamental science. Experimental measurement, computational simulations, and theoretical interpretation will be the three pillars for deciphering the dynamic exciton phenomena. From the viewpoint of computational simulations, molecular dynamics (MD) techniques combined with quantum chemical calculations, i.e., quantum molecular dynamics (QMD), has been the popular tool to simulate the dynamic exciton phenomena. The quantum chemical calculations, which are typically conducted on the basis of the density-functional theory (DFT), require the large computational resources and time. These have been the limiting factors for the accessible spatial and time scales by the QMD simulations. To extend the coverage of simulations to more complex, large-scale systems, we have developed efficient excited-state QMD methods that can include nonadiabatic effects. Our method combines the density-functional tight binding (DFTB) method, which is an approximate DFT, and the surface hopping method, which is a theoretical framework to incorporate the nonadiabatic effects into the QMD simulations. The method was further improved to be suitable for condensed-phase simulations explicitly including the environment, i.e., solvent, by using a “divide-and-conquer” style quantum chemical calculation technique. These theoretical framework enables us to simulate the coupled electronic–structural dynamics in excited states of systems consisting of 102–103 atoms[1,2,3]. In addition, using the developed method, we conducted the real-time simulations of the ultrafast processes invoked by photoexcitation of lead iodide perovskites, which are known as the key materials for perovskite solar cells. The dissociation of the exciton into the positive and negative charge carriers was observed. Moreover, the hot carrier cooling, where the charge carriers dissipate excess energy via the electron–phonon coupling and relax to the band edges, was also tracked. Finally, the direct evidence of the polaron formation, where the structural deformation is induced by the presence of charge carriers, was observed. These results highlight the importance of the coupling between electronic and structural degrees of freedom. In the talk, recent improvements in the methodology and future perspectives will also be presented[5]. References [1] H. Uratani and H. Nakai, J. Chem. Phys. 152, 224109 (2020). [2] H. Uratani, T. Morioka, T. Yoshikawa, and H. Nakai, J. Chem. Theory Comput. 16, 7299 (2020). [3] H. Uratani, T. Yoshikawa, and H. Nakai, J. Chem. Theory Comput. 17, 1290 (2021). [4] H. Uratani and H. Nakai, J. Phys. Chem. Lett. 11, 4448 (2020). [5] H. Uratani and H. Nakai, J. Chem. Theory Comput. in press. Figure 1

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6

Zhu, Tong, Jordan M. Snaider, Long Yuan, and Libai Huang. "Ultrafast Dynamic Microscopy of Carrier and Exciton Transport." Annual Review of Physical Chemistry 70, no. 1 (June 14, 2019): 219–44. http://dx.doi.org/10.1146/annurev-physchem-042018-052605.

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We highlight the recent progress in ultrafast dynamic microscopy that combines ultrafast optical spectroscopy with microscopy approaches, focusing on the application transient absorption microscopy (TAM) to directly image energy and charge transport in solar energy harvesting and conversion systems. We discuss the principles, instrumentation, and resolutions of TAM. The simultaneous spatial, temporal, and excited-state-specific resolutions of TAM unraveled exciton and charge transport mechanisms that were previously obscured in conventional ultrafast spectroscopy measurements for systems such as organic solar cells, hybrid perovskite thin films, and molecular aggregates. We also discuss future directions to improve resolutions and to develop other ultrafast imaging contrasts beyond transient absorption.

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7

Ouyang, Hao, Haitao Chen, Yuxiang Tang, Jun Zhang, Chenxi Zhang, Bin Zhang, Xiang’ai Cheng, and Tian Jiang. "All-optical dynamic tuning of local excitonic emission of monolayer MoS2 by integration with Ge2Sb2Te5." Nanophotonics 9, no. 8 (April 18, 2020): 2351–59. http://dx.doi.org/10.1515/nanoph-2019-0366.

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AbstractStrong quantum confinement and coulomb interactions induce tightly bound quasiparticles such as excitons and trions in an atomically thin layer of transitional metal dichalcogenides (TMDs), which play a dominant role in determining their intriguing optoelectronic properties. Thus, controlling the excitonic properties is essential for the applications of TMD-based devices. Here, we demonstrate the all-optical tuning of the local excitonic emission from a monolayer MoS2 hybridized with phase-change material Ge2Sb2Te5 (GST) thin film. By applying pulsed laser with different power on the MoS2/GST heterostructure, the peak energies of the excitonic emission of MoS2 can be tuned up to 40 meV, and the exciton/trion intensity ratio can be tuned by at least one order of magnitude. Raman spectra and transient pump-probe measurements show that the tunability originated from the laser-induced phase change of the GST thin film with charge transferring from GST to the monolayer MoS2. The dynamic tuning of the excitonic emission was all done with localized laser pulses and could be scaled readily, which pave a new way of controlling the excitonic emission in TMDs. Our findings could be potentially used as all-optical modulators or switches in future optical networks.

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8

Chen, Lijia, Lun Cai, Lianbin Niu, Pan Guo, and Qunliang Song. "Influence of Temperature on Exciton Dynamic Processes in CuPc/C60 Based Solar Cells." Micromachines 12, no. 11 (October 22, 2021): 1295. http://dx.doi.org/10.3390/mi12111295.

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Although the effect of high temperature on the performance of organic solar cells has been widely investigated, it is inevitably influenced by the associated annealing effect (which usually leads to film morphology change and variation in electrical properties), which makes the discussion more sophisticated. In this study, we simplified the issue and investigated the influence of low temperatures (from room temperature to 77 K) on the photocurrent and internal/external quantum efficiency of a CuPc/C60 based solar cell. We found that besides the charge dynamic process (charge transport), one or more of the exciton dynamic processes, such as exciton diffusion and exciton dissociation, also play a significant role in affecting the photocurrent of organic solar cells at different temperatures. Additionally, the results showed that the temperature had negligible influence on the absorption of the CuPc film as well as the exciton generation process, but obviously influenced the other two exciton dynamic processes (exciton diffusion and exciton dissociation).

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9

AKAI, I., T. KARASAWA, and T. KOMATSU. "OPTICAL STARK EFFECTS ON THE STACKING FAULT EXCITONS IN BiI3." Journal of Nonlinear Optical Physics & Materials 01, no. 02 (April 1992): 311–37. http://dx.doi.org/10.1142/s0218199192000169.

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A study is made of the optical Stark effects on quasi two-dimensional excitons localized at a stacking fault in layered crystal BiI 3. The dynamic coupling of the driven ground states and driven multiple exciton states by the strong photon field occurs for a wide frequency range of light, from negative to positive detuning. For the positive detuning excitation, an additional nonlinear effect peculiar to condensed matter was also observed. Time-resolved measurements in the sub-nanosecond and picosecond time domains confirmed ultrafast switching between the optical Stark effect and the additional nonlinear effect. From the dependence of the optical Stark shift on the excitation intensity, it is shown that the quasi two-dimensional excition transition has a very large dipole matrix element and third-order nonlinear susceptibility χ(3).

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10

Tikhomirov, S. A. "Ultrafast dynamics and mechanisms of non-stationary absorption in thin gallium selenide samples." Proceedings of the National Academy of Sciences of Belarus. Physics and Mathematics Series 57, no. 1 (April 2, 2021): 99–107. http://dx.doi.org/10.29235/1561-2430-2021-57-1-99-107.

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Herein, the dynamics and mechanisms of induced absorption in thin samples of gallium selenide under various excitation conditions are studied using femtosecond kinetic spectroscopy. We have registered several types of induced changes including induced absorption on free charge carriers (“hot” and thermalized electrons), bleaching and absorption due to the population of near-edge trap or exciton states, as well as rapid changes in the absorption of probing radiation in the region of the overlap of the exciting and probing pulses due to two-quantum two-frequency interband transitions. The time ranges of the relaxation processes are estimated. It is shown that when using relatively low-intensity long-wave excitation (790 nm), the resonant excitation of the near-edge states occurs mainly due to two-quantum two-frequency transitions followed by the formation of the dynamic equilibrium between bound and free electrons in the time range up to 5 ps. When electrons are excited deeply into the conduction band with the formation of hot free electrons and their subsequent thermalization to the bottom of the conduction band in the time range up to 1 ps, the population of the near-edge states and the establishment of the dynamic equilibrium between bound and free electrons is realized in the same time range (5 ps) as when they are excited “from below”.

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11

Anni, Marco, Arianna Cretì, Yuhai Zhang, Maria Luisa De Giorgi, and Mauro Lomascolo. "Investigation of the Role of the Environment on the Photoluminescence and the Exciton Relaxation of CsPbBr3 Nanocrystals Thin Films." Applied Sciences 10, no. 6 (March 21, 2020): 2148. http://dx.doi.org/10.3390/app10062148.

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In this work, we present a detailed optical investigation of the effects of the environment on the photoluminescence (PL) spectra and the relaxation dynamics of pristine and aged CsPbBr3 nanocrystal (NC) thin films. We demonstrate that, contrary to previous results on similar NCs, the PL intensity of pristine NCs is higher when the sample is in wet air than in vacuum, due to the passivation of defects reducing the free exciton trapping and the bound excitons non-radiative relaxation. The aged NCs show a PL intensity increase in wet air nine times stronger than the pristine ones, due to an interplay between static and dynamic effects, increasing the number of emitting NCs and reducing the non-radiative recombination rate of free excitons. These results improve the understanding of the possible interactions between perovskite NCs and the environment, which could be relevant for the development of optical gas sensors exploiting perovskite NCs.

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12

Wang, Jian, Junhui Huang, Yuanhe Li, Kun Ding, Desheng Jiang, Xiuming Dou, and Baoquan Sun. "Inhibited exciton spontaneous emission in InGaAs/GaAs quantum well by the phase-related scattering field of gold nanoparticles." Applied Physics Letters 120, no. 24 (June 13, 2022): 242102. http://dx.doi.org/10.1063/5.0088137.

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We have obtained long lifetime exciton emission in an InGaAs/GaAs quantum well (QW) when the QW film is transferred onto a silicon substrate covered by Au nanoparticles. It is found that the exciton lifetime increases from 0.301 ± 0.003 ns for the as-grown QW sample to 88 ± 6 ns for a QW film with Au nanoparticles, i.e., the spontaneous decay rate is inhibited with a factor of 1/300. The experimental condition of observing long lifetime excitons is very sensitive to the separation distance z between the QW and Au nanoparticles because phase-related scattering field mainly occurs at kz ∼1, where k is the wave vector. A classical dipole oscillator dynamic equation driven by the scattering field of Au nanoparticles can be employed to elucidate the experimental results.

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13

Lange, Christoph, Alex Hayat, Lee A. Rozema, Ardavan Darabi, Henry M. van Driel, Aephraim M. Steinberg, Bryan Nelsen, David W. Snoke, Loren N. Pfeiffer, and Kenneth W. West. "Observation of exciton-polariton ultrafast dynamic Stark effect." EPJ Web of Conferences 41 (2013): 04003. http://dx.doi.org/10.1051/epjconf/20134104003.

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14

Todisco, Francesco, Milena De Giorgi, Marco Esposito, Luisa De Marco, Alessandra Zizzari, Monica Bianco, Lorenzo Dominici, et al. "Ultrastrong Plasmon–Exciton Coupling by Dynamic Molecular Aggregation." ACS Photonics 5, no. 1 (October 12, 2017): 143–50. http://dx.doi.org/10.1021/acsphotonics.7b00554.

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15

NAKANO, MASAYOSHI, RYOHEI KISHI, HITOSHI FUKUI, TAKUYA MINAMI, HIROSHI NAGAI, KYOHEI YONEDA, SEAN BONNESS, and HIDEAKI TAKAHASHI. "THEORETICAL STUDY ON OPEN-SHELL NONLINEAR OPTICAL MOLECULAR SYSTEMS AND A DEVELOPMENT OF A NOVEL COMPUTATIONAL SCHEME OF EXCITON DYNAMICS." International Journal of Nanoscience 08, no. 01n02 (February 2009): 123–29. http://dx.doi.org/10.1142/s0219581x09005803.

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This contribution firstly elucidates a structure–property relationship in third-order nonlinear optical molecular systems with singlet diradical characters. It turns out that the second hyperpolarizabilities (γ) of the singlet open-shell molecules with intermediate diradical characters are significantly enhanced as compared with those of closed-shell and pure diradical molecules. The hybrid density functional theory method, i.e. UBHandHLYP, is applied to the calculations of γ of dimer models composed of singlet diradical diphenalenyl molecules, which show a remarkable enhancement of γ per monomer as decreasing the intermolecular distance. The second contribution is concerned with a development of ab initio molecular orbital configuration-interaction-based quantum master equation (QME) approach. This is found to provide both coherent processes, e.g. dynamic polarization and exciton (electron–hole pair) recurrence motion, and incoherent processes, e.g. exciton migration, in molecular systems. Using this approach, the electron/hole dynamics for dynamic polarizabilities α(ω) are examined for several π-conjugated linear chain systems, and the structural dependences of α(ω) are elucidated.

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16

Pan, Sai, Chenhong Sun, Yugang Zhou, Wei Chen, Rong Zhang, and Youdou Zheng. "Investigation of the Electroluminescence Mechanism of GaN-Based Blue and Green Light-Emitting Diodes with Junction Temperature Range of 120–373 K." Applied Sciences 10, no. 2 (January 8, 2020): 444. http://dx.doi.org/10.3390/app10020444.

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Junction temperature (Tj) and current have important effects on light-emitting diode (LED) properties. Therefore, the electroluminescence (EL) spectra of blue and green LEDs were investigated in a Tj range of 120–373 K and in a current range of 80–240 mA based on accurate real-time measurements of Tj using an LED with a built-in sensor unit. Two maxima of the emission peak energy with changing Tj were observed for the green LED, while the blue LED showed one maximum. This was explained by the transition between the donor-bound excitons (DX) and free excitons A (FXA) in the green LED. At low temperatures, the emission peak energy, full width at half maximum (FWHM), and radiation power of the green LED increase rapidly with increasing current, while those of the blue LED increase slightly. This is because when the strong spatial potential fluctuation and low exciton mobility in the green LED is exhibited, with the current increasing, more bonded excitons are found in different potential valleys. With a shallower potential valley and higher exciton mobility, excitons are mostly bound around the potential minima. The higher threshold voltage of the LEDs at low temperatures may be due to the combined effects of the band gap, dynamic resistance, piezoelectric polarization, and electron-blocking layer (EBL).

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17

Zhang, Yingjun, Xinhan Zhang, Bing Tang, Chuan Tian, Chunyan Xu, Hongxing Dong, and Weihang Zhou. "Realization of an all-optically controlled dynamic superlattice for exciton–polaritons." Nanoscale 10, no. 29 (2018): 14082–89. http://dx.doi.org/10.1039/c8nr02190b.

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18

Datta, Kanak, Zhengyang Lyu, Zidong Li, Takashi Taniguchi, Kenji Watanabe, and Parag B. Deotare. "Spatiotemporally controlled room-temperature exciton transport under dynamic strain." Nature Photonics 16, no. 3 (February 14, 2022): 242–47. http://dx.doi.org/10.1038/s41566-021-00951-3.

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19

Carreras, Abel, and David Casanova. "Simple evaluation of dynamic disorder effects on exciton transport." Journal of Chemical Physics 156, no. 4 (January 28, 2022): 044112. http://dx.doi.org/10.1063/5.0078406.

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20

Yu, Zhenyi, Yi-Shi Wu, Jianwei Chen, Chunlin Sun, and Hongbing Fu. "ortho-Heterofluorene perylenediimides: synthesis, photophysical, and exciton dynamic properties." Physical Chemistry Chemical Physics 18, no. 48 (2016): 32678–81. http://dx.doi.org/10.1039/c6cp04930c.

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We designed heavy-atom-free perylenediimides (PDIs) to prompt the intersystem crossing (ISC) by introducing electron donating heterofluorene groups at the head positions of electron-deficient PDI core.

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21

Ribeiro Junior, Luiz Antonio, Fábio Ferreira Monteiro, Bernhard Georg Enders, Antonio Luciano de Almeida Fonseca, Geraldo Magela e Silva, and Wiliam Ferreira da Cunha. "Dynamic Formation of Bipolaron–Exciton Complexes in Conducting Polymers." Journal of Physical Chemistry A 122, no. 15 (April 2, 2018): 3866–72. http://dx.doi.org/10.1021/acs.jpca.7b12185.

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22

Li, Xinmeng, Francesco Buda, Huub J. M. de Groot, and G. J. Agur Sevink. "Dynamic Disorder Drives Exciton Transfer in Tubular Chlorosomal Assemblies." Journal of Physical Chemistry B 124, no. 20 (April 28, 2020): 4026–35. http://dx.doi.org/10.1021/acs.jpcb.0c00441.

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23

Kulakovskii, V. D., S. S. Gavrilov, and N. A. Gippius. "Dynamic compression of exciton-polariton condensates in semiconductor microcavities." JETP Letters 106, no. 10 (November 2017): 686–91. http://dx.doi.org/10.1134/s0021364017220118.

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24

Izawa, Seiichiro. "(Invited) Photon Upconversion through Dynamic Exciton at Organic Semiconductor Interface." ECS Meeting Abstracts MA2022-01, no. 13 (July 7, 2022): 900. http://dx.doi.org/10.1149/ma2022-0113900mtgabs.

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Energy of photons, i.e. the wavelength of light, can be upgraded through interactions with materials—a process called photon upconversion (UC). Although UC in organic solids is important for various applications, such as in photovoltaics and bioimaging, conventional UC systems, based on intersystem crossing (ISC), suffer from low efficiency. Herein, we report a novel UC mechanism at heterojunctions of organic semiconductors in bilayer structures. The UC occurs by triplet formation during the charge separation and recombination through dynamic exciton: charge transfer (CT) state at the interface. This can efficiently convert the incident photons to triplets without relying on the ISC, whose rate is typically accelerated by the heavy-atom effect. As a result, a solid-state UC system is achieved with an external efficiency of two orders of magnitude higher than those of the conventional systems. Using this result, efficient UC, from near-infrared to visible light, cab be realized on flexible organic thin films under a weak light-emitting diode-induced excitation, observable by naked eyes. Reference: S. Izawa and M. Hiramoto, Nat. Photon., DOI: org/10.1038/s41566-021-00904-w.

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Demenev, A. A., A. S. Brichkin, S. S. Gavrilov, N. A. Gippius, and V. D. Kulakovskii. "Dynamic Compression of Spinor Exciton-Polariton Systems in Semiconductor Microcavities." Semiconductors 52, no. 14 (December 2018): 1827–32. http://dx.doi.org/10.1134/s1063782618140087.

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Emanuele, Emanuela, Krystyna Zakrzewska, Dimitra Markovitsi, Richard Lavery, and Philippe Millié. "Exciton States of Dynamic DNA Double Helices: Alternating dCdG Sequences." Journal of Physical Chemistry B 109, no. 33 (August 2005): 16109–18. http://dx.doi.org/10.1021/jp051833k.

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Peyghambarian, N., S. W. Koch, M. Lindberg, B. Fluegel, and M. Joffre. "Dynamic Stark effect of exciton and continuum states in CdS." Physical Review Letters 62, no. 10 (March 6, 1989): 1185–88. http://dx.doi.org/10.1103/physrevlett.62.1185.

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28

Auerhammer, Nina, Alexander Schulz, Alexander Schmiedel, Marco Holzapfel, Joscha Hoche, Merle I. S. Röhr, Roland Mitric, and Christoph Lambert. "Dynamic exciton localisation in a pyrene–BODIPY–pyrene dye conjugate." Physical Chemistry Chemical Physics 21, no. 18 (2019): 9013–25. http://dx.doi.org/10.1039/c9cp00908f.

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The photophysics of a molecular triad consisting of a BODIPY dye and two pyrene chromophores attached in 2-position are investigated by steady state and fs-time resolved transient absorption spectroscopy as well as by field induced surface hopping (FISH) simulations.

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N M, Anjan Kumar, Soumya Mukherjee, Anoop Sunny, B. Karthikeyan, and N. Kamaraju. "Investigation of self-trapped excitonic dynamics in hematite nanoforms through non-degenerate pump–probe transmission spectroscopy." Applied Physics Letters 121, no. 20 (November 14, 2022): 202102. http://dx.doi.org/10.1063/5.0123246.

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Non-degenerate pump–probe transmission spectroscopy is used to examine the ultrafast dynamics of photo-excited carriers in hematite nanoforms at various pump fluences. Using coupled rate equations, the kinetics of self-trapped exciton (STE) formation and its interaction with free excitons resulting in exciton annihilation were studied. It is shown from this model that the majority of the excitons were trapped by polaronic trap states to form self-trapped excitons within ∼3.5 ps. The findings indicate that free excitons and STEs interact non-linearly, similar to trap-assisted bi-molecular Auger recombination to annihilate one another. It is observed that there is substantial dependence of kinetics of STE formation and exciton decay on photo-excited exciton density, and the nature of this dependence indicates the reduced screening of electron–phonon interaction. Using the screening model applied to the rate constants of STE formation and decay, we estimate the saturation exciton density to be ∼3.3 × 1017 cm−3 and the average STE density to be ∼3.8 × 1018 cm−3 in the hematite nanoforms. We also noticed that doping K and Ni to hematite nanoforms up to 5% did not remarkably change the nature of the exciton dynamics.

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Atwater, Harry. "(Keynote) Van Der Waals Active Metasurfaces and Heterostructures for Phase Modulation and Polarization Conversion." ECS Meeting Abstracts MA2022-01, no. 12 (July 7, 2022): 861. http://dx.doi.org/10.1149/ma2022-0112861mtgabs.

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A grand challenge for nanophotonics is the realization of tunable metasurfaces enabling active control of the key constitutive properties of light – amplitude, phase, wavevector and polarization. Active metasurfaces that enable dynamic modulation of reflection amplitude, phase and polarization have been recently explored using several active materials and modulation phenomena, including carrier index in plasmonic ENZ structures, reorientation of liquid crystal molecules, electrooptic effects in quantum well heterostructures and index change in phase change materials. The rapid advances in understanding of exciton resonances in layered van der Waals materials has now stimulated thinking about active metasurfaces that exploit excitonic modulation phenomena to enable ‘van der Waals active metasurfaces’. As one example, I will describe recent advances in electrically reconfigurable polarization conversion across the telecommunication wavelength range in van der Waals layered materials, integrated in a Fabry-Pérot cavity. The large electrical tunability of the excitonic birefringence in tri-layer black phosphorus enables spectrally broadband polarization conversion over nearly half the Poincaré sphere. We observe both linear to circular and cross-polarization conversion with voltage, demonstrating dynamic access to polarization diversity. As a second example, we discuss the observed large gate tunability of the complex refractive index in monolayer MoSe2 by Fermi level modulation near the A and B excitonic resonances for temperatures between 4 K to 150 K. By tuning the charge density, we observe both temperature and carrier dependent epsilon-near-zero response in the permittivity and transition from metallic to dielectric near the A exciton energy, and directly observe active phase modulation in monolayer MoSe2 gated heterostructures, whose voltage dependence is consistent with our complex index measurements. These results have broad implications for the use of monolayer transition metal dichalcogenides in active metasurfaces, and I also will give a general outlook for the wide range of possibilities for active van der Waals metasurfaces.

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31

Mikhailov A. V., Trifonov A. V., Sultanov O. S., Yugova I. Yu., and Ignatiev I. V. "Quantum beats of light-hole and heavy-hole excitons in reflection spectra of GaAs/AlGaAs quantum well." Semiconductors 56, no. 7 (2022): 484. http://dx.doi.org/10.21883/sc.2022.07.54761.13.

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In this work we experimentally study dynamics of the heavy-hole and light-hole exciton states in a quantum well under coherent excitation of both excitonic resonances using co- and cross-linear and circular polarizations of pump and probe beams. Oscillations of basic parameters of excitonic resonances are observed. Their dependence on the polarization of the pump and probe beams is used to determine the structure of states of the heavy-hole and light-hole excitons by means of theoretical modelling of experimental data. Keywords: quantum well, excitons, quantum beats, light-hole exciton, heavy-hole exciton.

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32

Kim, Heedae, Jong Su Kim, and Jin Dong Song. "Temperature-Dependent Exciton Dynamics in a Single GaAs Quantum Ring and a Quantum Dot." Nanomaterials 12, no. 14 (July 7, 2022): 2331. http://dx.doi.org/10.3390/nano12142331.

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Micro-photoluminescence was observed while increasing the excitation power in a single GaAs quantum ring (QR) at 4 K. Fine structures at the energy levels of the ground (N = 1) and excited (N = 2) state excitons exhibited a blue shift when excitation power increased. The excited state exciton had a strong polarization dependence that stemmed from the asymmetric localized state. According to temperature-dependence measurements, strong exciton–phonon interaction (48 meV) was observed from an excited exciton state in comparison with the weak exciton–phonon interaction (27 meV) from the ground exciton state, resulting from enhanced confinement in the excited exciton state. In addition, higher activation energy (by 20 meV) was observed for the confined electrons in a single GaAs QR, where the confinement effect was enhanced by the asymmetric ring structure.

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33

Kim, Pyosang, Kyu Hyung Park, Woojae Kim, Tomoya Tamachi, Masahiko Iyoda, and Dongho Kim. "Relationship between Dynamic Planarization Processes and Exciton Delocalization in Cyclic Oligothiophenes." Journal of Physical Chemistry Letters 6, no. 3 (January 20, 2015): 451–56. http://dx.doi.org/10.1021/jz502395z.

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34

Raimondo, L., M. Laicini, P. Spearman, S. Tavazzi, and A. Borghesi. "Effect of static and dynamic disorder on exciton mobility in oligothiophenes." Journal of Chemical Physics 125, no. 2 (July 14, 2006): 024702. http://dx.doi.org/10.1063/1.2212943.

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35

Bryant, Garnett W. "Exciton states in quantum dot solids: excitation transfer and dynamic decorrelation." Physica B: Condensed Matter 314, no. 1-4 (March 2002): 15–19. http://dx.doi.org/10.1016/s0921-4526(01)01457-0.

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36

Moon, Hyowon, Gabriele Grosso, Chitraleema Chakraborty, Cheng Peng, Takashi Taniguchi, Kenji Watanabe, and Dirk Englund. "Dynamic Exciton Funneling by Local Strain Control in a Monolayer Semiconductor." Nano Letters 20, no. 9 (August 13, 2020): 6791–97. http://dx.doi.org/10.1021/acs.nanolett.0c02757.

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37

Becker, P. C., D. Lee, M. R. X. d. Barros, A. M. Johnson, A. G. Prosser, R. D. Feldman, R. F. Austin, and R. E. Behringer. "Femtosecond dynamic exciton bleaching in room temperature II-VI quantum wells." IEEE Journal of Quantum Electronics 28, no. 10 (1992): 2535–42. http://dx.doi.org/10.1109/3.159560.

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38

Шамирзаев, Т. С. "Рекомбинация и спиновая динамика экситонов в непрямозонных квантовых ямах и квантовых точках." Физика твердого тела 60, no. 8 (2018): 1542. http://dx.doi.org/10.21883/ftt.2018.08.46240.08gr.

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AbstractThe behavior of excitons in heterostructures with indirect-gap GaAs/AlAs quantum wells and (In, Al)As/AlAs quantum dots is discussed. The possibilities of controlled change of the exciton radiative recombination time in the range from dozens of nanoseconds to dozens of microseconds, experimental study of the spin dynamics of long-lived localized excitons, and use of the optical resonant methods for exciting the indirect-band exciton states are demonstrated.

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39

Shamirzaev, T. S., A. V. Shumilin, D. S. Smirnov, D. Kudlacik, S. V. Nekrasov, Yu G. Kusrayev, D. R. Yakovlev, and M. Bayer. "Optical Orientation of Excitons in a Longitudinal Magnetic Field in Indirect-Band-Gap (In,Al)As/AlAs Quantum Dots with Type-I Band Alignment." Nanomaterials 13, no. 4 (February 14, 2023): 729. http://dx.doi.org/10.3390/nano13040729.

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Exciton recombination and spin dynamics in (In,Al)As/AlAs quantum dots (QDs) with indirect band gap and type-I band alignment were studied. The negligible (less than 0.2 μeV) value of the anisotropic exchange interaction in these QDs prevents the mixing of the excitonic basis states and makes the formation of spin-polarized bright excitons possible under quasi-resonant, circularly polarized excitation. The recombination and spin dynamics of excitons are controlled by the hyperfine interaction between the electron and nuclear spins. A QD blockade by dark excitons was observed in the magnetic field, that eliminates the impact of nuclear spin fluctuations. A kinetic model which accounts for the population dynamics of the bright and dark exciton states as well as for the spin dynamics was developed to quantitatively describe the experimental data.

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40

Zheng, Yue Bing, Bala Krishna Juluri, Lin Lin Jensen, Daniel Ahmed, Mengqian Lu, Lasse Jensen, and Tony Jun Huang. "Exciton-Plasmon Coupling: Dynamic Tuning of Plasmon-Exciton Coupling in Arrays of Nanodisk-J-aggregate Complexes (Adv. Mater. 32/2010)." Advanced Materials 22, no. 32 (August 16, 2010): n/a. http://dx.doi.org/10.1002/adma.201090105.

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41

Imahori, Hiroshi, Yasuhiro Kobori, and Hironori Kaji. "Manipulation of Charge-Transfer States by Molecular Design: Perspective from “Dynamic Exciton”." Accounts of Materials Research 2, no. 7 (June 29, 2021): 501–14. http://dx.doi.org/10.1021/accountsmr.1c00045.

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42

Kobrak, Mark N., and Eric R. Bittner. "A dynamic model for exciton self-trapping in conjugated polymers. I. Theory." Journal of Chemical Physics 112, no. 12 (March 22, 2000): 5399–409. http://dx.doi.org/10.1063/1.481109.

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43

Kobrak, Mark N., and Eric R. Bittner. "A dynamic model for exciton self-trapping in conjugated polymers. II. Implementation." Journal of Chemical Physics 112, no. 12 (March 22, 2000): 5410–19. http://dx.doi.org/10.1063/1.481126.

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44

Cao, Xinqiang, Yishi Wu, Hongbing Fu, and Jiannian Yao. "Self-Assembly of Perylenediimide Nanobelts and Their Size-Tunable Exciton Dynamic Properties." Journal of Physical Chemistry Letters 2, no. 17 (August 12, 2011): 2163–67. http://dx.doi.org/10.1021/jz2009488.

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45

Zhang, Shengxia, Lijun Xu, Peipei Hu, Khan Maaz, Jian Zeng, Pengfei Zhai, Zongzhen Li, Li Liu, and Jie Liu. "Excitonic performance and ultrafast dynamics in defective WSe₂." Applied Physics Letters 121, no. 8 (August 22, 2022): 083102. http://dx.doi.org/10.1063/5.0098100.

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Understanding and facilitating defects in two-dimensional transition metal dichalcogenides (TMDCs) are of fundamental importance for their application in optoelectronic devices and valleytronic devices. In this study, swift heavy ion (SHI) irradiation was applied to introduce defects in monolayer WSe2 in a controlled manner. Temperature-dependent photoluminescence and transient absorption spectroscopy are employed to investigate the excitonic performances in defective WSe2. It is observed that the trion emission rises up alongside exciton emission for WSe2 irradiated with elevated ion fluences. Defects introduced by SHI irradiation can strongly localize carriers and weaken the exciton–phonon coupling and further affect the optical signatures of the excitons. Photoexcited electron–hole pairs were suppressed to form excitons due to the weaken phonon scattering, and the population of exciton was reduced for the irradiated WSe2. These results reveal that SHI irradiation is an effective technique to explore defect dependence of exciton formation and evolution dynamics in TMDCs, which have important implications for various optoelectronic applications.

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Kunsel, T., T. L. C. Jansen, and J. Knoester. "Scaling relations of exciton diffusion in linear aggregates with static and dynamic disorder." Journal of Chemical Physics 155, no. 13 (October 7, 2021): 134305. http://dx.doi.org/10.1063/5.0065206.

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47

Kunsel, T., T. L. C. Jansen, and J. Knoester. "Scaling relations of exciton diffusion in linear aggregates with static and dynamic disorder." Journal of Chemical Physics 155, no. 13 (October 7, 2021): 134305. http://dx.doi.org/10.1063/5.0065206.

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48

Dutta, Rajesh, and Biman Bagchi. "Effects of dynamic disorder on exciton migration: Quantum diffusion, coherences, and energy transfer." Journal of Chemical Physics 145, no. 16 (October 28, 2016): 164907. http://dx.doi.org/10.1063/1.4966035.

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49

Voityuk, Alexander A. "Effects of dynamic disorder on exciton delocalization and photoinduced charge separation in DNA." Photochemical & Photobiological Sciences 12, no. 8 (2013): 1303. http://dx.doi.org/10.1039/c2pp25389e.

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50

Meier, T., F. Rossi, P. Thomas, and S. W. Koch. "Dynamic Localization in Anisotropic Coulomb Systems: Field Induced Crossover of the Exciton Dimension." Physical Review Letters 75, no. 13 (September 25, 1995): 2558–61. http://dx.doi.org/10.1103/physrevlett.75.2558.

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