Excitonic devices with van der Waals heterostructures: valleytronics meets twistronics

Ciarrocchi, Alberto; Tagarelli, Fedele; Avsar, Ahmet

doi:10.1038/s41578-021-00408-7

Cited by 121 publications

(103 citation statements)

References 183 publications

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“…The large increases in electrochemical performance, particularly the low resistance and high stability also suggest that more fundamental investigations may be required. Recent studies in two dimensional materials like graphene [40] and transition metal dichalcogenides [41] have indicated that the relative orientation of molecular sheets can dramatically influence electron transport and result in exotic electical properties like superconductivity. Quantum tunneling has also been found to play a significant role in enhancing conductivity in two dimensional nanoparticle assemblies, and is perhaps one factor behind the low resistance of the thin film electrodes.…”

Section: Resultsmentioning

confidence: 99%

Shear and Solvent-mediated Fabrication of Layered Double Hydroxide Superstructures for High Rate, Stable Supercapacitor Cathodes

Jose

Ковалев

Lapkin

2022

Preprint

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The development of sustainable energy economies is blocked by the lack of stable electrical energy sources with high power and energy densities. Next generation supercapacitors utilizing two-dimensional layered double hydroxides (LDHs) promise to fill this need in hybrid and standalone architectures; however, despite their high power and energy densities, LDH supercapacitors have poor stability. New methods for creating robust LDH electrodes are necessary to prevent this degradation. In this study, the recently developed annular microreactor is used to synthesize defect-rich NiCo LDH nanocrystals. A simple, solvent-based method is used to rationally generate binder-free, superstructured-thin films on Ni foam electrodes. Control over crystallite size, thinness and orientation improves contact with the conductive substrate, increase reactivity and improve structural stability. Optimized electrodes are fabricated with specific capacitances from 3,000-5,000 F/g at charging rates as high as 1,000 A/g, a performance that was retained after 20,000 cycles. This is twice as stable at 5,000 times the current density of the most stable reported Ni-based supercapacitor. Ultimately, this study addresses key concerns in electrode development, introduces new approaches through reactor technology and solvent-mediated assembly, and opens new ground for more fundamental inquiries into the mechanisms of electron transport in 2D systems.

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Section: Resultsmentioning

confidence: 99%

Shear and Solvent-mediated Fabrication of Layered Double Hydroxide Superstructures for High Rate, Stable Supercapacitor Cathodes

Jose

Ковалев

Lapkin

2022

Preprint

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“…Transition metal dichalcogenides (TMDs) have long attracted the attention of researchers due to their fascinating physical properties for optoelectronic device applications, including sizable bandgap energies, large absorption coefficients, high electron mobility, and superior mechanical flexibility [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. In particular, it has been noted that the exciton–photon interactions dominate the optical responses of TMDs even at room temperature.…”

Section: Introductionmentioning

confidence: 99%

“…In particular, it has been noted that the exciton–photon interactions dominate the optical responses of TMDs even at room temperature. In two-dimensional (2D) TMD layers, strongly bound electron-hole pairs (excitons) are generated by the weak dielectric screening and strong geometric confinement [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 ]. The exciton binding energy in TMDs is as large as hundreds of meV, which is one to two orders of magnitude larger than those of conventional semiconductors [ 1 , 2 , 3 , 4 , 5 , 6 ].…”

Section: Introductionmentioning

confidence: 99%

“…In two-dimensional (2D) TMD layers, strongly bound electron-hole pairs (excitons) are generated by the weak dielectric screening and strong geometric confinement [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 ]. The exciton binding energy in TMDs is as large as hundreds of meV, which is one to two orders of magnitude larger than those of conventional semiconductors [ 1 , 2 , 3 , 4 , 5 , 6 ]. Integration of TMDs with photonic nanostructures can broaden our understanding of exciton physics, providing valuable insights into excitonic devices [ 4 , 5 , 6 ].…”

Section: Introductionmentioning

confidence: 99%

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Self-Hybridized Exciton-Polaritons in Sub-10-nm-Thick WS2 Flakes: Roles of Optical Phase Shifts at WS2/Au Interfaces

et al. 2022

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Exciton–polaritons (EPs) can be formed in transition metal dichalcogenide (TMD) multilayers sustaining optical resonance modes without any external cavity. The self-hybridized EP modes are expected to depend on the TMD thickness, which directly determines the resonance wavelength. Exfoliated WS2 flakes were prepared on SiO2/Si substrates and template-stripped ultraflat Au layers, and the thickness dependence of their EP modes was compared. For WS2 flakes on SiO2/Si, the minimum flake thickness to exhibit exciton–photon anticrossing was larger than 40 nm. However, for WS2 flakes on Au, EP mode splitting appeared in flakes thinner than 10 nm. Analytical and numerical calculations were performed to explain the distinct thickness-dependence. The phase shifts of light at the WS2/Au interface, originating from the complex Fresnel coefficients, were as large as π/2 at visible wavelengths. Such exceptionally large phase shifts allowed the optical resonance and resulting EP modes in the sub-10-nm-thick WS2 flakes. This work helps us to propose novel optoelectronic devices based on the intriguing exciton physics of TMDs.

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“…Introduction -Van der Waals heterostructures (vdWH) of atomically thin semiconductors [1] such as transition metal dichalcogenides (TMDCs) have proven to be an effective platform for designing nano and micro-scale optoelectronic and photonic devices for a variety of applications ranging from quantum information processing [2][3][4][5][6][7] to valleytronics-based devices [8][9][10][11][12]. One promising feature of these heterostructures is their ability to host excitons with large binding energies [12].…”

mentioning

confidence: 99%

A photonic integrated chip platform for interlayer exciton valley routing

Mandal¹,

Gupta²,

Sohoni³

et al. 2022

Preprint

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Interlayer excitons in two dimensional semiconductor heterostructures show suppressed electronhole overlap resulting in longer radiative lifetimes as compared to intralyer excitons. Such tightly bound interlayer excitons are relevant for important optoelectronic applications including light storage and quantum communication. Their optical accessibility is, however, limited due to their outof-plane transition dipole moment. In this work, we design a CMOS compatible photonic integrated chip platform for enhanced near field coupling of these interlayer excitons with the whispering gallery modes of a microresonator, exploiting the high confinement of light in a small modal volume and high quality factor of the system. Our platform allows for highly selective emission routing via engineering an asymmetric light transmission which facilitates efficient readout and channeling of the excitonic valley state from such systems.

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Excitonic devices with van der Waals heterostructures: valleytronics meets twistronics

Cited by 121 publications

References 183 publications

Shear and Solvent-mediated Fabrication of Layered Double Hydroxide Superstructures for High Rate, Stable Supercapacitor Cathodes

Shear and Solvent-mediated Fabrication of Layered Double Hydroxide Superstructures for High Rate, Stable Supercapacitor Cathodes

Self-Hybridized Exciton-Polaritons in Sub-10-nm-Thick WS2 Flakes: Roles of Optical Phase Shifts at WS2/Au Interfaces

A photonic integrated chip platform for interlayer exciton valley routing

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