Dielectric disorder in two-dimensional materials

Raja, Archana; Waldecker, Lutz; Zipfel, Jonas; Cho, Yeongsu; Brem, Samuel; Ziegler, Jonas D.; Kulig, Marvin; Taniguchi, Takashi; Watanabe, Kenji; Malić, Ermin; Heinz, Tony F.; Berkelbach, Timothy C.; Chernikov, Alexey

doi:10.1038/s41565-019-0520-0

Cited by 295 publications

(341 citation statements)

References 51 publications

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“…Another feasible explanation is that structural disorder is much larger in hybrid perovskites than in TMDCs due to the ionic nature. Structural disorder results in fluctuations in the energy landscape, slowing down exciton transport 45 . We suggest that exciton transport in 2D perovskites can be further enhanced through structural tuning to increase rigidity and reduce structural disorder, for instance, by employing phenyl group motifs at the R site 3 .…”

Section: Resultsmentioning

confidence: 99%

Long-range exciton transport and slow annihilation in two-dimensional hybrid perovskites

et al. 2020

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Two-dimensional hybrid organic-inorganic perovskites with strongly bound excitons and tunable structures are desirable for optoelectronic applications. Exciton transport and annihilation are two key processes in determining device efficiencies; however, a thorough understanding of these processes is hindered by that annihilation rates are often convoluted with exciton diffusion constants. Here we employ transient absorption microscopy to disentangle quantum-well-thickness-dependent exciton diffusion and annihilation in twodimensional perovskites, unraveling the key role of electron-hole interactions and dielectric screening. The exciton diffusion constant is found to increase with quantum-well thickness, ranging from 0.06 ± 0.03 to 0.34 ± 0.03 cm 2 s −1 , which leads to long-range exciton diffusion over hundreds of nanometers. The exciton annihilation rates are more than one order of magnitude lower than those found in the monolayers of transition metal dichalcogenides. The combination of long-range exciton transport and slow annihilation highlights the unique attributes of two-dimensional perovskites as an exciting class of optoelectronic materials.

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Section: Resultsmentioning

confidence: 99%

Long-range exciton transport and slow annihilation in two-dimensional hybrid perovskites

et al. 2020

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“…More importantly, because plasmons in monolayer metallic TMDs originate mostly from electron orbitals of the innermost transition metal layer, we expect that the plasmon wavefunction does not extend too much outside the structure, and hence plasmons in monolayer metallic TMDs are more robust against substrate phonons than plasmons in graphene. While our estimate of the lifetime is an upper bound for an intrinsic sample, extrinsic effects such as ripples and defects, which needs to be considered in applications, can also be partially reduced with substrate engineering and encapsulation 42 .…”

Section: Resultsmentioning

confidence: 99%

Universal slow plasmons and giant field enhancement in atomically thin quasi-two-dimensional metals

et al. 2020

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Plasmons depend strongly on dimensionality: while plasmons in three-dimensional systems start with finite energy at wavevector q = 0, plasmons in traditional two-dimensional (2D) electron gas disperse as ω p $ ffiffi ffi q p . However, besides graphene, plasmons in real, atomically thin quasi-2D materials were heretofore not well understood. Here we show that the plasmons in real quasi-2D metals are qualitatively different, being virtually dispersionless for wavevectors of typical experimental interest. This stems from a broken continuous translational symmetry which leads to interband screening; so, dispersionless plasmons are a universal intrinsic phenomenon in quasi-2D metals. Moreover, our ab initio calculations reveal that plasmons of monolayer metallic transition metal dichalcogenides are tunable, long lived, able to sustain field intensity enhancement exceeding 10 7 , and localizable in real space (within~20 nm) with little spreading over practical measurement time. This opens the possibility of tracking plasmon wave packets in real time for novel imaging techniques in atomically thin materials.

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“…In general, optical excitations, in particular bound excitons, are less affected by dielectric screening because of the neutral nature of such excitations. On the other hand, more loosely bound excitons or excitons with charge transfer character [39,40], present larger electron-hole separations and consequently experience stronger renormalization by the dielectric environment. While the effect of dielectric screening on optical excitations, in particular the lowest bound excitons in 2D materials, are easier to probe experimentally as compared to the QP gap, the theoretical treatment is limited by the assumption of static screening.…”

Section: Fig 4 the Reduction Of The Qp Band Gap Of The Semiconductomentioning

confidence: 99%

Electrically controlled dielectric band gap engineering in a two-dimensional semiconductor

Riis-Jensen¹,

Lu²,

Thygesen³

2020

Phys. Rev. B

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Dielectric disorder in two-dimensional materials

Cited by 295 publications

References 51 publications

Long-range exciton transport and slow annihilation in two-dimensional hybrid perovskites

Long-range exciton transport and slow annihilation in two-dimensional hybrid perovskites

Universal slow plasmons and giant field enhancement in atomically thin quasi-two-dimensional metals

Electrically controlled dielectric band gap engineering in a two-dimensional semiconductor

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