Exciton-driven renormalization of quasiparticle band structure in monolayer 
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Lin, Yi; Chan, Yang-Hao; Lee, Woojoo; Lu, Li‐Syuan; Li, Zhenglu; Chang, Wen-Hao; Shih, Chih‐Kang; Kaindl, Robert A.; Louie, Steven G.; Lanzara, Alessandra

doi:10.1103/physrevb.106.l081117

Cited by 15 publications

(14 citation statements)

References 72 publications

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“…In addition, it is the norm for TA data of semiconductor nanoparticles to have spectrally overlapping signals, both bleach and induced absorption, and these can complicate the measured temporal profiles of the features. Of particular importance here is recent theoretical and experimental results that indicate there is a prompt shifting of the quantum-confinement states that occurs with photoexcitation and the resultant changes in screening and shielding that alter the band structure and effective masses of the carriers. − We have termed this shifting as quantum-state renormalization (QSR), and we have shown QSR results in bleach and induced absorption throughout the spectral region of the semiconductor nanoparticles. , The contributions from the QSR appear during the excitation pulse in TA experiments, and the energies of the features can shift with time as the carriers relax to the band-edge states. Consequently, the temporal profiles of TA bleach signals often contain contributions from QSR that appear on ultrashort time scales as well as from the occupation of carriers in the different quantum-confinement states.…”

Section: Discussionmentioning

confidence: 97%

Facet-Specific Electron Transfer in Pseudo-Two-Dimensional Wurtzite Cadmium Selenide Nanocrystals

Meyer,

Chen,

Loomis

et al. 2023

J. Phys. Chem. C

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Ligand-exchange reactions of wurtzite CdSe quantum platelets (QPs) and quantum belts (QBs) with methyl viologen (MV2+) and the derivative ligands MV2+(CH2) n NH2 (n = 2, 4, or 6) are investigated. The QP and QB photoluminescence is quenched after partial ligand exchange. Spectroscopic and compositional data establish that this initial ligand substitution occurs on the thin QP and QB edges. The MV2+(CH2) n NH2 ligands are shown to be more-efficient photoluminescence quenchers than the parent MV2+ ion. The ligands on the thin, nonpolar, long-edge facets quench the photoluminescence via the trapping of excitons. Transient absorption experiments indicate the excitons dissociate, and electron transfer to the MV2+(CH2) n NH2 ligands only occurs at the polar, short-edge facets of the wurtzite CdSe QPs and QBs. Electron transfer to the MV2+(CH2) n NH2 ligands occurs within 100 fs when exciting at the band edge and on longer time scales, due to intraband relaxation, when exciting at higher energies.

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Section: Discussionmentioning

confidence: 97%

Facet-Specific Electron Transfer in Pseudo-Two-Dimensional Wurtzite Cadmium Selenide Nanocrystals

Meyer,

Chen,

Loomis

et al. 2023

J. Phys. Chem. C

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“…As opposed to the bandgap reduction from screening of free carriers, an increase in the bandgap by 40 meV was recently observed in the monolayer MoS 2 /HOPG system. 125 The TR-ARPES experiment was carried out at lower excitation densities below the Mott threshold, which created excitons in MoS 2 instead. This phenomenon was assigned to exciton-driven band renormalizations due to the simultaneous enhancement of band effective mass, which was supported by excitonic many-body theoretical calculations.…”

Section: Tmdc Monolayer Dynamicsmentioning

confidence: 99%

Time- and angle-resolved photoemission spectroscopy (TR-ARPES) of TMDC monolayers and bilayers

Liu

2023

Chem. Sci.

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“…The specific problem is the 2D semiconductor energy levels move under working photocatalytic or photoelectrochemical conditions, due to both the applied potential (𝐸) [11][12][13][14] and absorption of photons [15][16][17][18][19] . The phenomenon called band gap renormalization (BGR) involves movement of the semiconductor band edges, resulting in a potential-or light intensity-dependent G 0 ´ that currently remains unknown or illdefined.…”

Section: 𝑘𝑇mentioning

confidence: 99%

Quantifying interfacial energetics of 2D semiconductor electrodes using in situ spectroelectrochemistry and many-body theory

Almaraz

Sayer

Toole

et al. 2023

Preprint

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Hot carrier extraction occurs in 2D semiconductor photoelectrochemical cells [Austin et. al., PNAS, 2023, 120, e2220333120]. Boosting the energy efficiency of hot carrier-based photoelectrochemical cells requires maximizing the hot carrier extraction rate relative to the cooling rate. One could expect to tune the hot carrier extraction rate constant (k_ET) via a Marcus-Gerischer relationship, where k_ET depends exponentially on ΔG0´ (the standard driving force for interfacial electron transfer). ΔG0´ is defined as the energy level difference between a semiconductor’s conduction/valence band (CB/VB) minima/maxima and the redox potential of reactant molecules in solution. A major challenge in the electrochemistry community is that conventional approaches to quantify ΔG0´ for bulk semiconductors (e.g., Mott-Schottky measurements) cannot be directly applied to ultrathin 2D electrodes. The specific problem is that enormous electronic bandgap changes (>0.5 eV) and CB/VB edge movement take place upon illuminating or applying a potential to a 2D semiconductor electrode. Here, we develop an in situ absorbance spectroscopy approach to quantify interfacial energetics of 2D semiconductor/electrolyte interfaces using a minimal many-body model. Our results show that band edge movement in monolayer MoS2 is significant (0.2-0.5 eV) over a narrow range of applied potentials (0.2-0.3 V). Such large band edge shifts could change k_ET by a factor of 10-100, which has important consequences for practical solar energy conversion applications. We discuss the current experimental and theoretical knowledge gaps that must be addressed to minimize the error in the proposed optical approach.

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Exciton-driven renormalization of quasiparticle band structure in monolayer MoS2

Cited by 15 publications

References 72 publications

Facet-Specific Electron Transfer in Pseudo-Two-Dimensional Wurtzite Cadmium Selenide Nanocrystals

Facet-Specific Electron Transfer in Pseudo-Two-Dimensional Wurtzite Cadmium Selenide Nanocrystals

Time- and angle-resolved photoemission spectroscopy (TR-ARPES) of TMDC monolayers and bilayers

Quantifying interfacial energetics of 2D semiconductor electrodes using in situ spectroelectrochemistry and many-body theory

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