A roadmap for interlayer excitons

Lin, Kai-Qiang

doi:10.1038/s41377-021-00544-3

Cited by 14 publications

(6 citation statements)

References 17 publications

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“…Unuchek et al used layers of two atomically thin transition-metal dichalcogenides, namely, molybdenum disulfide (MoS 2 ) and tungsten diselenide (WSe 2 ), 848 but such a prototype can in principle be constructed of organic semiconductor layers as well. One layer in the above heterostructure serves as electron donor and the other as electron acceptor, so light generates excitons that have CT character and are referred to as hybrid, 849 indirect, 850 or interlayer 851 excitons.…”

Section: Excitonic Circuitsmentioning

confidence: 99%

Dynamics of Excitons in Conjugated Molecules and Organic Semiconductor Systems

Dimitriev

2022

Chem. Rev.

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The exciton, an excited electron–hole pair bound by Coulomb attraction, plays a key role in photophysics of organic molecules and drives practically important phenomena such as photoinduced mechanical motions of a molecule, photochemical conversions, energy transfer, generation of free charge carriers, etc. Its behavior in extended π-conjugated molecules and disordered organic films is very different and very rich compared with exciton behavior in inorganic semiconductor crystals. Due to the high degree of variability of organic systems themselves, the exciton not only exerts changes on molecules that carry it but undergoes its own changes during all phases of its lifetime, that is, birth, conversion and transport, and decay. The goal of this review is to give a systematic and comprehensive view on exciton behavior in π-conjugated molecules and molecular assemblies at all phases of exciton evolution with emphasis on rates typical for this dynamic picture and various consequences of the above dynamics. To uncover the rich variety of exciton behavior, details of exciton formation, exciton transport, exciton energy conversion, direct and reverse intersystem crossing, and radiative and nonradiative decay are considered in different systems, where these processes lead to or are influenced by static and dynamic disorder, charge distribution symmetry breaking, photoinduced reactions, electron and proton transfer, structural rearrangements, exciton coupling with vibrations and intermediate particles, and exciton dissociation and annihilation as well.

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Section: Excitonic Circuitsmentioning

confidence: 99%

Dynamics of Excitons in Conjugated Molecules and Organic Semiconductor Systems

Dimitriev

2022

Chem. Rev.

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“…In TMDC monolayers, the excitons have an in-plane dipole moment and without net electric charge, thus the exciton flux is challenging to be manipulated by the in-plane electric field. Fortunately, in the van der Waals heterostructure with type-II band alignment, the confinement of oppositely charged carriers in different layers can form IX with an out-of-plane (z) direction dipole moment p. [37,[74][75][76] Therefore, the out-of-plane electric field E z can modulate the exciton energy by δE = −p z E z , and drives the exciton flow toward the lower energy regions.…”

Section: Electric Controlmentioning

confidence: 99%

“…Fortunately, in the van der Waals heterostructure with type‐II band alignment, the confinement of oppositely charged carriers in different layers can form IX with an out‐of‐plane ( z ) direction dipole moment p . [ 37,74–76 ] Therefore, the out‐of‐plane electric field E z can modulate the exciton energy by δE = − p z E z , and drives the exciton flow toward the lower energy regions. The electrically controlled exciton flux was firstly realized in the type‐II quantum wells, where the IX can be formed with a binding energy of ≈10 meV.…”

Section: Control Of 2d Exciton Fluxmentioning

confidence: 99%

Molding 2D Exciton Flux toward Room Temperature Excitonic Devices

Dai

Luo

et al. 2022

Adv Materials Technologies

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optoelectronic elements and devices. Owing to the unique talents of electrons and photons, the efficient photonic communication and electronic processing of signals have been proved as the essential and core components the information technology. Electrons as charged particles are sensitive to surroundings because of strong Coulomb interaction, leading to the bottleneck of nanosecond response time for integrated electric devices. The electronic response time and the conversation between photonic and electronic systems inevitably limit the operation speed in the conventional optoelectronic. [1] Thus developing compact photonic devices performing the essential logic operations is promising to accelerate information transmission and processing. In this direction, some simple prototypes, including optoelectronic transistor, compact microring resonator-based modulator, and Mach-Zehnder modulator, have been demonstrated. [2][3][4] The high integration of photonic devices is challenging due to the optical diffraction limit. Although the latter devices have achieved switching speeds exceeding several gigahertz, high packing density is greatly limited by their active-region dimensions of 10-100 µm. Excitons, or bound electron−hole pairs, Devices operating with excitons have promising prospects for overcoming the dilemma of response time and integration in current generation of electron-or/and photon-based elements and devices. In combination with the advantages of emerging twistronics and valleytronics, the atomically thin transition metal dichalcogenide semiconductors open up new opportunities for pursuing practical excitonic devices, where the strong exciton binding energy enables operating exciton at room temperature. The essential and foremost step toward exciton devices is the control of spatiotemporal exciton flux, which is density-dependent and affected by the complex many-body interactions. It can be effectively controlled by the strain, electric field, electron-doping, and local dielectric environment. Intriguingly, exotic phenomena such as exciton condensation, electron-hole liquid, exciton Hall effects, and exciton halo effects can be occurred in 2D exciton system, providing new possibilities for excitonic devices. Up to now, the proof-of-principle of room temperature exciton devices, including excitonic switching and transistor, exciton guides, and excitonic nanolaser, have been realized. Here the authors review the recent advances in molding 2D exciton flux from basic principle, manipulation, exotic phenomena to promising applications and discuss the opportunities and challenges in pushing the frontiers of room temperature excitonic devices.

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“…Furthermore, in a homo/hetero-bilayer (HBs) sample made from TMDCs, ultrafast interlayer charge transfer can also facilitate the formation of interlayer excitons (ILXs) with long lifetimes and large exciton binding energies observed at RT in prior work 2 . Therefore, TMDCs have attracted significant attention for both fundamental studies of novel quantum optical phenomena and photonic/optoelectronic applications in recent times [3][4][5][6][7][8][9] .…”

Section: Introductionmentioning

confidence: 99%

Tailoring Exciton Dynamics in TMDC Heterobilayers in the Quantum Plasmonic Regime

Rahaman

Kim

et al. 2023

Preprint

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Control of excitons in transition metal dichalcogenides (TMDCs) and their heterostructures is fundamentally interesting for tailoring light-matter interactions and exploring their potential applications in high-efficiency optoelectronic and nonlinear photonic devices. While both intra- and interlayer excitons in TMDCs have been heavily studied, their behavior in the quantum tunneling regime, in which the TMDC or its heterostructure is optically excited and concurrently serves as a tunnel junction barrier, remains unexplored. Here, using the degree of freedom of a metallic probe in an atomic force microscope, we investigated both intralayer and interlayer excitons dynamics in TMDC heterobilayers via locally controlled junction current in a finely tuned sub-nanometer tip-sample cavity. Our tip-enhanced photoluminescence measurements reveal a significantly different exciton-quantum plasmon coupling for intralayer and interlayer excitons due to different orientation of the dipoles of the respective e-h pairs. Using a steady-state rate equation fit, we extracted field gradients, radiative and nonradiative relaxation rates for excitons in the quantum tunneling regime with and without junction current. Our results show that tip-induced radiative (nonradiative) relaxation of intralayer (interlayer) excitons becomes dominant in the quantum tunneling regime due to the Purcell effect. These findings have important implications for near-field probing of excitonic materials in the strong-coupling regime.

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A roadmap for interlayer excitons

Cited by 14 publications

References 17 publications

Dynamics of Excitons in Conjugated Molecules and Organic Semiconductor Systems

Dynamics of Excitons in Conjugated Molecules and Organic Semiconductor Systems

Molding 2D Exciton Flux toward Room Temperature Excitonic Devices

Tailoring Exciton Dynamics in TMDC Heterobilayers in the Quantum Plasmonic Regime

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