Microscopic theory of exciton-exciton annihilation in two-dimensional semiconductors

Steinhoff, Alexander; Jahnke, F.; Florian, Matthias

doi:10.1103/physrevb.104.155416

Cited by 13 publications

(11 citation statements)

References 60 publications

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“…It follows that the low temperatures facilitate the EEA because they favor the population of excitons having small momentum. [47] This trend is in agreement with an EEA process that lasts longer at higher temperature because of the increase of the crystal dimension due to the thermal expansion and of the thermal vibrations of the lattice that reduce the EEA efficiency. We cannot exclude that this trend is also emphasized by the increase of 2D perovskite absorption at low temperature that determines an increase of the exciton density and hence an enhancement of the scattering rate.…”

Section: Dynamics Of the Transient Absorptionsupporting

confidence: 84%

“…This result is in line with the values already obtained for other 2D materials such as MoS 2 in (4.3 ± 1.1) × 10 −2 cm 2 s −1 [90] and for RPPs with butylammonium as the spacer (1.7 ± 0.5) × 10 −2 cm 2 s −1 . [47] The EEA rate constants are very similar to the values found for RPPs having butylammonium and dodecylammonium, suggesting that the organic spacer only slightly affects the EEA rate. Although the exciton binding energies of DAMAPI-1 and MoS 2 are similar (≈600 meV), the EEA rate constant is lower for the RPP system with respect to the MoS 2 .…”

Section: Dynamics Of the Transient Absorptionsupporting

confidence: 59%

“…[33,44] A transient absorption microscopy experiment has shown the occurrence in 2D perovskites of a slow exciton-exciton annihilation (EEA), [46] which is a non-radiative many-body interaction, a form of Auger recombination where the kinetic energy of an exciton is transferred to another exciton. [47] This non-radiative channel, which is still not completely and extensively studied, is strictly connected to the exciton energetics and more in general to the optoelectronic properties of 2D perovskite materials.…”

Section: Introductionmentioning

confidence: 99%

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Band Structure and Exciton Dynamics in Quasi‐2D Dodecylammonium Halide Perovskites

Ammirati

Martelli

O’Keeffe

et al. 2023

Advanced Optical Materials

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Femtosecond transient absorption spectroscopy (FTAS) is an important tool to investigate the physics of halide perovskites having different dimensionality, morphology, and architectures, giving insights into the electronic and excitonic optical transitions. Here, FTAS on monolayer (n = 1) and multilayer (n = 2, 3) quasi‐2D perovskites in the Ruddlesden–Popper phase: DA2MAn‐1PbnI3n+1 (DAMAPI) is presented, with the dodecylammonium (DA = CH3‐(CH2)11‐NH3+) as the spacer and methylammonium (MA = CH3NH3+) as the organic cation for samples with n > 1. The measurements, performed at 77 K and room temperature using several pump energies and excitation densities, allow the observation of different absorption bleaching energies. Those energies are compared with the results of first‐principles theoretical simulations based on density functional theory, the GW method, and the Bethe–Salpeter equation and assigned to transitions involving excitons with principal quantum numbers 1s and 2s. The temporal analysis of the absorption bleaching indicates the exciton–exciton annihilation as the main relaxation mechanism in the first picoseconds after excitation, while exciton radiative recombination is observed at longer time delays (>100 ps). Therefore, FTAS allows the study of the carrier dynamics and, given its high sensitivity to carrier density changes, the observation of spectral features not observable with steady‐state measurements.

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Section: Dynamics Of the Transient Absorptionsupporting

confidence: 84%

Section: Dynamics Of the Transient Absorptionsupporting

confidence: 59%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Band Structure and Exciton Dynamics in Quasi‐2D Dodecylammonium Halide Perovskites

Ammirati

Martelli

O’Keeffe

et al. 2023

Advanced Optical Materials

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“…Thus, based on the halo formation, we can infer the Auger recombination rate γ as γ h‑BNencap < γ PDMS ≪ γ bare . We note that such a huge variance in the Auger recombination rate cannot be explained by the change of the Coulomb-mediated Auger scattering. , Thus, we infer that the decisive factor is the change of the defect-assisted Auger recombination rate due to various dielectric disorders. In a defective system, the exciton detrapping rate decreases (ratio of excitons being trapped increases) with increased trap depth. ,, The portion of excitons being trapped is also proportional to the density of traps.…”

Section: Resultsmentioning

confidence: 99%

Dielectric Engineering for Manipulating Exciton Transport in Semiconductor Monolayers

Leon

Lee

et al. 2021

Nano Lett.

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The dielectric screening from the disordered media surrounding atomically thin transition metal dichalcogenides (TMDs) monolayers modifies the effective defect energy levels and thereby the transport and energy dynamics of excitons. In this work, we study this effect in WSe2 monolayers for different combinations of surrounding dielectric media. Specifically, we study the source of the anomalous diffusion of excitons in the WSe2 monolayer and attribute the anomaly to the modification of the energy distribution of defect states in different disordered dielectric environments. We use this insight to manipulate exciton transport by engineering the dielectric environment using a graphene/hexagonal boron nitride (h-BN) moiré superlattice. Finally, we observe that the effect of dielectric disorder is even more significant at high excitation fluences, contributing to the nonequilibrium phonon drag effect. These results provide an important step toward achieving control over the exciton energy transport for next-generation opto-excitonic devices.

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“…We connected the full many-body quantum dynamics , of TMD electrons, holes, and excitons − with a macroscopic exciton drift-diffusion equation, where the measured F gradient and mobility μ enter as inputs; the full discussion is provided in Supplementary Section II. The diffusivity D is defined by temperature T , as given by eq .…”

Section: Methodsmentioning

confidence: 99%

Enhanced Exciton Drift Transport through Suppressed Diffusion in One-Dimensional Guides

Li,

Florian,

Datta

et al. 2023

ACS Nano

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Drift-diffusion dynamics is investigated in a one-dimensional (1D) exciton guide at room temperature. Spatial engineering of the exciton energy in a WSe2 monolayer is achieved using local strain to confine and direct exciton transport. An unexpected and massive deviation from the Einstein relation is observed and correlated to exciton capture by defects. We find that the capture reduces exciton temperature and diffusion so much that drift transport visibility improves to 38% as excitons traverse asymmetrically over regions with occupied defect states. Based on measurements over multiple potential gradients, we estimate the exciton mobility to be 169 ± 39 cm2/(eV s) at room temperature. Experiments at elevated exciton densities reveal that the exciton drift velocity monotonically increases with exciton density, unlike exciton mobility, due to contributions from nonequilibrium many-body effects.

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Microscopic theory of exciton-exciton annihilation in two-dimensional semiconductors

Cited by 13 publications

References 60 publications

Band Structure and Exciton Dynamics in Quasi‐2D Dodecylammonium Halide Perovskites

Band Structure and Exciton Dynamics in Quasi‐2D Dodecylammonium Halide Perovskites

Dielectric Engineering for Manipulating Exciton Transport in Semiconductor Monolayers

Enhanced Exciton Drift Transport through Suppressed Diffusion in One-Dimensional Guides

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