The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
Jie Shan - One of the best experts on this subject based on the ideXlab platform.
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Opportunities and challenges of interlayer Exciton control and manipulation
Nature Nanotechnology, 2018Co-Authors: Kin Fai Mak, Jie ShanAbstract:Advances in van der Waals heterostructures allow the control of interlayer Excitons by electrical and other means, promising exciting opportunities for high-temperature Exciton condensation and valley–spin optoelectronics. This Commentary discusses practical prospects of using electrical control of interlayer Excitons in van der Waals heterostructures for high-temperature Exciton condensation and valley–spin optoelectronics.
L. R. Weiss - One of the best experts on this subject based on the ideXlab platform.
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spin fine structure reveals biExciton geometry in an organic semiconductor
Physical Review Letters, 2020Co-Authors: K. M. Yunusova, S. L. Bayliss, T. Chanelière, V. Derkach, J. E. Anthony, Alexei Chepelianskii, L. R. WeissAbstract:In organic semiconductors, bi-Exciton states are key intermediates in carrier-multiplication and Exciton annihilation. Of particular recent interest is the spin-2 (quintet) bi-Exciton. Comprised of two triplet Excitons, the bi-Exciton can be formed by singlet fission (the formation of two triplet Excitons from one singlet state) or by triplet-triplet annihilation (the reverse process). Of interest for photovoltaics and photocatalysis, the wavefunction of these optically dark bi-Excitons is difficult to probe and predict. However, the local geometry of the pair-state is imprinted in the fine structure of its spin Hamiltonian. To access the fine structure of the quintet-state we develop and deploy broadband optically detected magnetic resonance (0-9 GHz). Here we correlate the experimentally extracted spin structure with the molecular crystal structure to identify the specific molecular pairings on which the bi-Exciton state resides.
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Spin fine-structure reveals bi-Exciton geometry in an organic semiconductor
2019Co-Authors: K. M. Yunusova, S. L. Bayliss, T. Chanelière, V. Derkach, J. E. Anthony, Alexei Chepelianskii, L. R. WeissAbstract:In organic semiconductors, bi-Exciton states are key intermediates in carrier-multiplication and Exciton annihilation. Of particular recent interest is the spin-2 (quintet) bi-Exciton. Comprised of two triplet Excitons, the bi-Exciton can be formed by singlet fission (the formation of two triplet Excitons from one singlet state) or by triplet-triplet annihilation (the reverse process). Of interest for photovoltaics and photocatalysis, the wavefunction of these optically dark bi-Excitons is difficult to probe and predict. However, the local geometry of the pair-state is imprinted in the fine structure of its spin Hamiltonian. To access the fine structure of the quintet-state we develop and deploy broadband optically detected magnetic resonance (0-9 GHz). Here we correlate the experimentally extracted spin structure with the molecular crystal structure to identify the specific molecular pairings on which the bi-Exciton state resides.
T. Chanelière - One of the best experts on this subject based on the ideXlab platform.
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spin fine structure reveals biExciton geometry in an organic semiconductor
Physical Review Letters, 2020Co-Authors: K. M. Yunusova, S. L. Bayliss, T. Chanelière, V. Derkach, J. E. Anthony, Alexei Chepelianskii, L. R. WeissAbstract:In organic semiconductors, bi-Exciton states are key intermediates in carrier-multiplication and Exciton annihilation. Of particular recent interest is the spin-2 (quintet) bi-Exciton. Comprised of two triplet Excitons, the bi-Exciton can be formed by singlet fission (the formation of two triplet Excitons from one singlet state) or by triplet-triplet annihilation (the reverse process). Of interest for photovoltaics and photocatalysis, the wavefunction of these optically dark bi-Excitons is difficult to probe and predict. However, the local geometry of the pair-state is imprinted in the fine structure of its spin Hamiltonian. To access the fine structure of the quintet-state we develop and deploy broadband optically detected magnetic resonance (0-9 GHz). Here we correlate the experimentally extracted spin structure with the molecular crystal structure to identify the specific molecular pairings on which the bi-Exciton state resides.
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Spin fine-structure reveals bi-Exciton geometry in an organic semiconductor
2019Co-Authors: K. M. Yunusova, S. L. Bayliss, T. Chanelière, V. Derkach, J. E. Anthony, Alexei Chepelianskii, L. R. WeissAbstract:In organic semiconductors, bi-Exciton states are key intermediates in carrier-multiplication and Exciton annihilation. Of particular recent interest is the spin-2 (quintet) bi-Exciton. Comprised of two triplet Excitons, the bi-Exciton can be formed by singlet fission (the formation of two triplet Excitons from one singlet state) or by triplet-triplet annihilation (the reverse process). Of interest for photovoltaics and photocatalysis, the wavefunction of these optically dark bi-Excitons is difficult to probe and predict. However, the local geometry of the pair-state is imprinted in the fine structure of its spin Hamiltonian. To access the fine structure of the quintet-state we develop and deploy broadband optically detected magnetic resonance (0-9 GHz). Here we correlate the experimentally extracted spin structure with the molecular crystal structure to identify the specific molecular pairings on which the bi-Exciton state resides.
Kin Fai Mak - One of the best experts on this subject based on the ideXlab platform.
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Opportunities and challenges of interlayer Exciton control and manipulation
Nature Nanotechnology, 2018Co-Authors: Kin Fai Mak, Jie ShanAbstract:Advances in van der Waals heterostructures allow the control of interlayer Excitons by electrical and other means, promising exciting opportunities for high-temperature Exciton condensation and valley–spin optoelectronics. This Commentary discusses practical prospects of using electrical control of interlayer Excitons in van der Waals heterostructures for high-temperature Exciton condensation and valley–spin optoelectronics.
Guillaume Cassabois - One of the best experts on this subject based on the ideXlab platform.
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Exciton‐Exciton interactions in single-wall carbon nanotubes
2012Co-Authors: Guillaume CassaboisAbstract:The one-dimensionality of carriers in SWNTs results in strong Coulomb interactions, the non-perturbative binding of an electron-hole pair into an Exciton being the first striking signature. Besides the Excitonic nature of the optical resonances in SWNTs, several time-resolved experiments have shown the evidence that the strong Coulomb correlations also affect the relaxation dynamics in SWNTs. In particular, photoluminescence and pump-probe measurements using ultrafast excitation pulses have revealed that the population relaxation dynamics is driven by an efficient Exciton-Exciton annihilation (EEA) process, even at low Exciton density. This Auger process is one type of Exciton-Exciton interaction where one Exciton recombines while the second one is promotted to a high-energy state. Since EEA is known to play a key role in the population relaxation of Frenkel Excitons in organic materials, especially J-aggregates and conjugated polymers, the high efficiency of EEA in SWNTs suggests that Excitons in SWNTs are mostly of Frenkel type. In the following, we will show that the EEA process does not account for the Excitonic collision-induced broadening measured in SWNTs. Power-dependent measurements of the Excitonic homogeneous linewidth demonstrate the predominance of another type of Exciton-Exciton interaction, namely elastic Exciton-Exciton scattering (EES). This latter process redistributes the population within Exciton bands and contributes to pure dephasing of the Excitonic transition. EES is widely observed for Wannier Excitons in inorganic bulk semiconductors or quantum wells but not for Frenkel Excitons in organic materials, leading to a refined picture of Excitons in SWNTs in between Wannier and Frenkel Excitons.
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Elastic Exciton-Exciton scattering in photoexcited carbon nanotubes
Physical Review Letters, 2011Co-Authors: D. T. Nguyen, C. Voisin, Ph. Roussignol, C. Roquelet, Jean-sébastien Lauret, Guillaume CassaboisAbstract:We report on original nonlinear spectral hole-burning experiments in single wall carbon nanotubes that bring evidence of pure dephasing induced by Exciton-Exciton scattering. We show that the collision-induced broadening in carbon nanotubes is controlled by Exciton-Exciton scattering as for Wannier Excitons in inorganic semiconductors, while the population relaxation is driven by Exciton-Exciton annihilation as for Frenkel Excitons in organic materials. We demonstrate that this singular behavior originates from the intrinsic one-dimensionality of Excitons in carbon nanotubes, which display unique hybrid features of organic and inorganic systems.
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Elastic Exciton-Exciton scattering in carbon nanotubes
2011Co-Authors: Guillaume CassaboisAbstract:The one-dimensionality of carriers in single-wall carbon nanotubes results in strong Coulomb interactions. Besides the non-perturbative binding of an electron-hole pair into an Exciton, several time-resolved experiments have shown evidence for efficient Exciton-Exciton interactions. These studies have revealed that the Exciton recombination is driven by an Exciton-Exciton annihilation mechanism. In fact such an Auger process is known to play a key role in the population relaxation of Frenkel Excitons in organic materials, and especially J-aggregates and conjugated polymers. Here we show that the similarity with organic molecules breaks down for the dephasing induced by Exciton-Exciton interactions. We have studied the Exciton dephasing by means of the non-linear optical technique of spectral-hole burning. We show that the collision broadening is surprisingly not limited by Exciton-Exciton Auger annihilation. We demonstrate that the coherence relaxation is determined by quasi-elastic Exciton-Exciton scattering within the fundamental Excitonic band. This process is typical of Wannier Excitons in inorganic semiconductors, while Exciton annihilation is usually observed for Frenkel Excitons in organic compounds. Our results reveal the unique non-linear properties of carbon nanotubes in between inorganic and organic materials.
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Exciton collision broadening in single-wall carbon nanotubes
2011Co-Authors: D. T. Nguyen, C. Voisin, Ph. Roussignol, C. Roquelet, Jean-sébastien Lauret, Guillaume CassaboisAbstract:The one-dimensionality of carriers in single-wall carbon nanotubes results in strong Coulomb interactions. Besides the non-perturbative binding of an electron-hole pair into an Exciton, several time-resolved experiments have shown evidence for efficient Exciton-Exciton interactions. These studies have revealed that the Exciton recombination is driven by an Exciton-Exciton annihilation mechanism. In fact such an Auger process is known to play a key role in the population relaxation of Frenkel Excitons in organic materials, and especially J-aggregates and conjugated polymers. Here we show that the similarity with organic molecules breaks down for the dephasing induced by Exciton-Exciton interactions. We have studied the Exciton dephasing by means of the non-linear optical technique of spectral-hole burning. We show that the collision broadening is surprisingly not limited by Exciton-Exciton Auger annihilation. We demonstrate that the coherence relaxation is determined by quasi-elastic Exciton-Exciton scattering within the fundamental Excitonic band. This process is typical of Wannier Excitons in inorganic semiconductors, while Exciton annihilation is usually observed for Frenkel Excitons in organic compounds. Our results reveal the unique non-linear properties of carbon nanotubes in between inorganic and organic materials.
