Theoretical investigation of electron-hole complexes in anisotropic two-dimensional materials

Chaves, Andrey; Mayers, Matthew Z.; Peeters, F. M.; Reichman, David R.

doi:10.1103/physrevb.93.115314

Cited by 40 publications

(53 citation statements)

References 37 publications

(29 reference statements)

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“…To the best of our knowledge, no experimental or theoretical evidence of exciton binding in single-layer arsenene is available in the literature, apart from Ref. [62], which reports the exciton binding energy of bilayer arsenene as ∼500 meV. When combined with our results, this indicates that E b will decrease upon increasing the number of layers.…”

Section: Excitonic Effectssupporting

confidence: 71%

Optical properties of single-layer and bilayer arsenene phases

2016

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An extensive investigation of the optical properties of single-layer buckled and washboard arsenene and their bilayers was performed, starting from layered three-dimensional crystalline phase of arsenic using density functional and many-body perturbation theories combined with random phase approximation. Electron-hole interactions were taken into account by solving the Bethe-Salpeter equation, suggesting first bound exciton energies on the order of 0.7 eV. Thus, many-body effects were found to be crucial for altering the optical properties of arsenene. The light absorption of single-layer and bilayer arsenene structures in general falls within the visible-ultraviolet spectral regime. Moreover, directional anisotropy, varying the number of layers, and applying homogeneous or uniaxial in-plane tensile strain were found to modify the optical properties of two-dimensional arsenene phases, which could be useful for diverse photovoltaic and optoelectronic applications.

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Section: Excitonic Effectssupporting

confidence: 71%

Optical properties of single-layer and bilayer arsenene phases

2016

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“…Besides, X 2 and X 3 states are obtained with different polarization directions, as previously discussed, therefore, binding energies of T ± 2 and T ± 3 trions are more conveniently calculated and are discussed separately. Trion binding energies are observed to be tens of meV, similar to those of monolayer TMDCs [59,61] and black phosphorus [50], except for T + 3 . Positive and negative trions have significantly different binding energies, especially for T ± 3 (≈8 meV), which can be experimentally verified by checking the trion peak position as a function of the doping of the TiS 3 monolayer.…”

Section: B Neutral and Charged Excitonsmentioning

confidence: 65%

“…In this case, a different change of coordinates is proposed, in order to reduce the dimensionality of the problem (see, e.g., the Supplemental Material of Ref. [50]): we take R (with corresponding momentum P ) as the relative coordinate between an electron-hole pair, and r (with corresponding momentum p) as the relative coordinate between the extra charge (extra electron or hole, for negatively or positively charged trions, respectively) and the center of mass of that first electron-hole pair. This leads to a trion Hamiltonian…”

Section: B Neutral and Charged Excitonsmentioning

confidence: 99%

Ab initio and semiempirical modeling of excitons and trions in monolayer TiS3

et al. 2018

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We explore the electronic and the optical properties of monolayer TiS 3 , which shows in-plane anisotropy and is composed of a chain-like structure along one of the lattice directions. Together with its robust direct band gap, which changes very slightly with stacking order and with the thickness of the sample, the anisotropic physical properties of TiS 3 make the material very attractive for various device applications. In this study, we present a detailed investigation on the effect of the crystal anisotropy on the excitons and the trions of the TiS 3 monolayer. We use many-body perturbation theory to calculate the absorption spectrum of anisotropic TiS 3 monolayer by solving the Bethe-Salpeter equation. In parallel, we implement and use a Wannier-Mott model for the excitons that takes into account the anisotropic effective masses and Coulomb screening, which are obtained from ab initio calculations. This model is then extended for the investigation of trion states of monolayer TiS 3 . Our calculations indicate that the absorption spectrum of monolayer TiS 3 drastically depends on the polarization of the incoming light, which excites different excitons with distinct binding energies. In addition, the binding energies of positively and the negatively charged trions are observed to be distinct and they exhibit an anisotropic probability density distribution.

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“…3h. The strain modulation of the binding energy E b gives a relatively minor correction, so that more complex bound states that are formed at high excitation regimes, such as biexcitons [66], are expected to respond to strain gradients in a similar way as excitons, albeit possibly with reduced lifetimes at high densities [47]. The efficient modulation of optoelectronic properties with strain, a hallmark property of this material, was recently showcased by optical absorption experiments in elastically rippled few-layer BP [19].…”

Section: Results and Discusionmentioning

confidence: 99%

Inverse Funnel Effect of Excitons in Strained Black Phosphorus

et al. 2016

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We study the effects of strain on the properties and dynamics of Wannier excitons in monolayer (phosphorene) and few-layer black phosphorus (BP), a promising two-dimensional material for optoelectronic applications due to its high mobility, mechanical strength, and strain-tunable direct band gap. We compare the results to the case of molybdenum disulphide (MoS 2 ) monolayers. We find that the so-called funnel effect, i.e., the possibility of controlling exciton motion by means of inhomogeneous strains, is much stronger in few-layer BP than in MoS 2 monolayers and, crucially, is of opposite sign. Instead of excitons accumulating isotropically around regions of high tensile strain like in MoS 2 , excitons in BP are pushed away from said regions. This inverse funnel effect is moreover highly anisotropic, with much larger funnel distances along the armchair crystallographic direction, leading to a directional focusing of exciton flow. A strong inverse funnel effect could enable simpler designs of funnel solar cells and offer new possibilities for the manipulation and harvesting of light.

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Theoretical investigation of electron-hole complexes in anisotropic two-dimensional materials

Cited by 40 publications

References 37 publications

Optical properties of single-layer and bilayer arsenene phases

Optical properties of single-layer and bilayer arsenene phases

Ab initio and semiempirical modeling of excitons and trions in monolayer TiS3

Inverse Funnel Effect of Excitons in Strained Black Phosphorus

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