Interlayer‐State‐Coupling Dependent Ultrafast Charge Transfer in MoS<sub>2</sub>/WS<sub>2</sub> Bilayers

Zhang, Jin; Hong, Hao; Lian, Chao; Ma, Wei; Xu, Xiaozhi; Zhou, Xu; Fu, Huixia; Liu, Kaihui; Meng, Sheng

doi:10.1002/advs.201700086

Cited by 91 publications

(99 citation statements)

References 52 publications

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“…Future experiments include gating the heterostructures with controlled carrier densities and spectrally separated excitonic resonances to further clarify their roles in exciton dephasing and population relaxation[17,74]. Also, previous studies about the ultrafast charge transfer between layers within the MoS2/WS2 heterostructures reveal the fs scale dynamics which can be tuned significantly by changing stacking configuration[53,[63][64]. So future ultrafast pump-probe spectroscopy experiment on our trilayer compared with the bilayer heterostructure can be an interesting topic about the effect of extra WSe2 layer, inducing its stacking configuration, on the charge transfer dynamics.…”

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confidence: 90%

Enhanced interlayer neutral excitons and trions in trilayer van der Waals heterostructures

et al. 2018

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Vertically stacked van der Waals heterostructures constitute a promising platform for providing tailored band alignment with enhanced excitonic systems. Here we report the first observations of neutral and charged interlayer excitons in trilayer WSe2-MoSe2-WSe2 van der Waals heterostructures and their dynamics. The addition of a WSe2 layer in the trilayer leads to significantly higher photoluminescence quantum yields and tunable spectral resonance compared to its bilayer heterostructures at cryogenic temperatures. The observed enhancement in the photoluminescence quantum yield is due to significantly larger electronhole overlap and higher light absorbance in the trilayer heterostructure, supported via firstprinciple pseudopotential calculations based on spin-polarized density functional theory. We further uncover the temperature-and power-dependence, as well as time-resolved photoluminescence of the trilayer heterostructure interlayer neutral excitons and trions. Our study elucidates the prospects of manipulating light emission from interlayer excitons and designing atomic heterostructures from first-principles for optoelectronics. In two-dimensional (2D) materials, Coulomb-induced electronic states of excitons have been examined as a platform to understand many-body carrier-carrier interactions. These excitonic interactions dominate in layered materials due to quantum confinement and reduced dielectric screening. 2D atomic crystals of transition metal dichalcogenides (TMDs) have provided new opportunities in the studies of single-exciton single-photon interactions, spin-orbit coupling, ultrafast dynamics, and nanoelectronic devices [1-22]. Layer-by-layer stacking of TMDs-based van der Waals (vdWs) heterostructures has recently captured the attention of the scientific community where the tailored band alignment with diverse 2D materials can be achieved via advanced 2D growth and transfer techniques [23-28]. This has allowed the extension of indirect excitons with spatially separated electrons and holes from, for example, coupled quantum wells in GaAs/AlGaAs [29,30] to TMD vdW heterostructure bilayers, where they are referred to as interlayer excitons. These interlayer excitons exhibit rich physics in TMDs-based vdWs heterostructures due to the novel atomic granularity control through layer-by-layer stacking and the chiral properties of quantum electronic states [8,31,32]. Recently several studies observed that heterostructure interlayer excitons feature long lifetimes, spin-valley polarization by circularlypolarized pumping, near-unity valley polarization via large magnetic splitting, and charge transfer at the heterogeneous interfaces [32-45].Here we demonstrate TMDs-based vdWs heterostructures composed of a three-layer WSe2-MoSe2-WSe2 stack to achieve unique band alignment that promotes efficient interlayer radiative recombination. We first design the heterostructure through pseudopotential calculations based on Supplementary Information Enhanced interlayer neutral excitons and trions in trilayer van der Waals ...

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confidence: 90%

Enhanced interlayer neutral excitons and trions in trilayer van der Waals heterostructures

et al. 2018

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“…[1][2][3][4] Due to their importance, considerable efforts were made to investigate the photoinduced charge transfer dynamics of these materials from the theoretical point of view. 3,[5][6][7][8][9][10][11] For example, transition-metal dichalcoge nide (TMD) van der Waals heterostructures MoS2/WS2 attracted tremendous interests due to their potential applicability as optoelectronic and solar energy conversion devices. [1][2][3][4][12][13][14][15] By using photoluminescence and femtosecond pump-probe measurements, Hong et al 12 found that the hole transfer in MoS2/WS2 was at the femtosecond scale (50 fs), indicating it is a promising candidate for optoelectronic and photovoltaic applicatio ns.…”

Section: Tocmentioning

confidence: 99%

“…The ultrafast charge transfer at TMD heterostructure interface has been further convinced by other experiments. [13][14][15] This process has also been investigated by different theoretical simulations 3,[5][6][7][8][9][10][11] . For example, Zheng et al 6 used ab initio nonadiabatic molecular dynamics based on time-dependent Kohn-Sham equation and surface hopping method to show that the ultrafast interlayer hole transfer is strongly promoted by an adiabatic mechanism through phonon excitation occurring on 20 fs, which is consistent with the experimental results.…”

Section: Tocmentioning

confidence: 99%

Diabatic Hamiltonian construction in van der Waals heterostructure complexes

et al. 2019

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A diabatization method is developed for the approximated description of the photoinduced charge separation/transfer processes in the van der Waals (vdW) heterostructure complex, which is based on the wavefunction projection approach using a plane wave basis set in the framework of the single-particle picture. We build the diabatic Hamiltonian for the description of the interlayer photoinduced hole-trans fer process of the two-dimensional vdW MoS2/WS2 heterostructure complexes. The diabatic Hamiltonian gives the energies of the localized valence band states (located at MoS2 and valence band states (located at WS2), as well as the couplings between them.The wavefunction projection method provides a practical and reasonable approach to construct the diabatic model in the description of photoinduced charge transfer processes in the vdW heterostructure complexes.

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“…Since the charge carrier transfer occurs mainly due to the overlap of interlayer states, photoexcitation charge carrier transfer dynamics certainly shows dependence on the interlayer stacking orders (twisting, translation and spacing) and interactions. Recent results on the basis of TDDFT demonstrate that specific interlayer registry between MoS 2 and WS 2 can significantly modulate the interlayer charge transfer, in particular, changes the time scale from 100 to 1,000 fs . It was further unraveled that the transfer rate is governed by the coupling between specific interlayer states, instead of the overall interlayer coupling strength.…”

Section: Photoexcitation Dynamics Of Chargr Carriersmentioning

confidence: 99%

Photoexcited charge carrier behaviors in solar energy conversion systems from theoretical simulations

Wei

Huang

Dai

2019

WIREs Comput Mol Sci

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Solar energy bears great potential in the substitution of conventional fossil fuels to enable a sustainable world. In order to harness and use solar energy, photocatalytic and photovoltaic systems made of semiconductor materials have been developed to convert sunlight into energy (electricity) based on the photoelectrochemical effects.Photoelectric events are related with the light-energy (electricity) conversion process, including photon absorption, photoexcited charge carrier separation and recombination, charge carrier transport, and photocurrent generation, as well as electron plasmonic resonance. We focus on the recent state-of-the-art simulation methods correspondingly mimicking these photogenerated charge carrier behaviors, taking electron-phonon, electron-exciton, and exciton-exciton interactions into account. Results can be obtained from the standard density function theory (DFT) for ground-state properties, many-body perturbation theory for band gap renormalization and optical absorption, time-domain DFT in combination with nonadiabatic molecular dynamics for photoexcitation dynamics, nonequilibrium Green's function and self-consistent theory for charge carrier transport properties, and classical Maxwell's equations in discrete dipole approximation for localized surface plasmon resonance absorption and near-field enhancement. In combination of the results from these simulation methods, a complete and consistent picture describing the fundamental photoelectric process in light-energy (electricity) conversion could be obtained. Simulation results offer guidelines for experimental efforts and provide new basic insights into the underlying mechanisms and the design principles for next-generation photocatalytic and photovoltaic devices of high solar light utilization efficiency.

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Interlayer‐State‐Coupling Dependent Ultrafast Charge Transfer in MoS₂/WS₂ Bilayers

Cited by 91 publications

References 52 publications

Enhanced interlayer neutral excitons and trions in trilayer van der Waals heterostructures

Enhanced interlayer neutral excitons and trions in trilayer van der Waals heterostructures

Diabatic Hamiltonian construction in van der Waals heterostructure complexes

Photoexcited charge carrier behaviors in solar energy conversion systems from theoretical simulations

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Interlayer‐State‐Coupling Dependent Ultrafast Charge Transfer in MoS2/WS2 Bilayers

Cited by 91 publications

References 52 publications

Enhanced interlayer neutral excitons and trions in trilayer van der Waals heterostructures

Enhanced interlayer neutral excitons and trions in trilayer van der Waals heterostructures

Diabatic Hamiltonian construction in van der Waals heterostructure complexes

Photoexcited charge carrier behaviors in solar energy conversion systems from theoretical simulations

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Interlayer‐State‐Coupling Dependent Ultrafast Charge Transfer in MoS₂/WS₂ Bilayers