Photoluminescence quantum yields for atomically thin-layered ReS2: Identification of indirect-bandgap semiconductors

Mohamed, Nur Baizura; Shinokita, Keisuke; Wang, Xiaofan; Lim, Hong En; Tan, Dezhi; Miyauchi, Yuhei; Matsuda, Kazunari

doi:10.1063/1.5037116

Cited by 39 publications

(37 citation statements)

References 44 publications

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“…However, an indirect bandgap of 1.47 eV has been reported 30 . Low photoluminescence (PL) quantum yield generally observed in all thickness appear to suggest that ReS 2 is indirect semiconductor 31 , while k-space photoemission microscopy revealed a direct bandgap in the bilayer (2L) ReS 2 32 . On the second issue, early experimental and first-principle studies have suggested that the interlayer coupling in ReS 2 is much weaker than other TMDs 5 .…”

Section: Introductionmentioning

confidence: 95%

Interlayer charge transfer in ReS2/WS2 van der Waals heterostructures

Zereshki

Peng

et al. 2019

Phys. Rev. B

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We observed ultrafast charge transfer between distorted-1T -ReS 2 with anisotropic in-plane electronic and optical properties and 2H-WS 2 that is in-plane isotropic. Heterostructures of monolayer ReS 2 /monolayer WS 2 and bilayer ReS 2 /monolayer WS 2 were fabricated by mechanical exfoliation and dry transfer techniques. Significant photoluminescence quenching of WS 2 in the heterostructures indicates efficient charge transfer. In femtosecond transient absorption measurements, it was found that holes injected in monolayer or bilayer ReS 2 transfer to WS 2 on a time scale shorter than time resolution of the measurement. This observation provides evidence that the holes are delocalized in bilayer ReS 2 , revealing strong van der Waals interlayer couplings. These results also show that ReS 2 and WS 2 form type-II heterostructures with excellent charge transfer properties.

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Section: Introductionmentioning

confidence: 95%

Interlayer charge transfer in ReS2/WS2 van der Waals heterostructures

Zereshki

Peng

et al. 2019

Phys. Rev. B

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“…The subsequent experimental studies, however, strongly oppose these predictions about the structural and electronic properties, revealing strong layer-dependent optical [11,27] and vibrational [28] properties of ReS 2 . An additional indication of lesser quantum yields of photoluminescence (PL) with lowering thicknesses [29] also contradicts the direct band gap nature of monolayer and few-layered ReS 2 . The optical response divulges that, starting from the monolayer up to seven layers, ReS 2 remains an indirect band gap semiconductor [28].…”

Section: Introductionmentioning

confidence: 99%

Two-dimensional ReS2 : Solution to the unresolved queries on its structure and inter-layer coupling leading to potential optical applications

Gadde

Karmakar

Maji

et al. 2021

Phys. Rev. Materials

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Over the last few years, ReS 2 has generated a myriad of unattended queries regarding its structure, the concomitant thickness-dependent electronic properties, and its apparently contrasting experimental optical response. In this paper, with elaborate first-principles investigations, using density functional theory (DFT) and time-dependent DFT, we identify the structure of ReS 2 , which is capable of reproducing and analyzing the layer-dependent optical response. The theoretical results are further validated by an in-depth structural, chemical, optical, and optoelectronic analysis of the large-area ReS 2 thin films, grown by the chemical vapor deposition (CVD) process. Micro-Raman, x-ray photoelectron spectroscopy, cross-sectional transmission electron microscopy, and energy-dispersive x-ray analysis have enabled the optimization of the uniform growth of the CVD films. The correlation between the optical and electronic properties was established by static photoluminescence and excited state transient absorption measurements. Sulfur vacancy-induced localized mid-gap states render a significantly long lifetime of the excitons in these films. The ionic gel top-gated photodetectors, fabricated from the as-prepared CVD films, exhibit a large photo-response of ∼5 A/W and a remarkable detectivity of ∼10 11 Jones. The outcome of this paper will be useful in promoting the application of vertically grown large-area films in the field of optics and opto-electronics.

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“…The PL intensity and absorption data of the reference sample are then measured using microscopes for comparison with data obtained from the 1L-TMD samples using the same experimental conditions [27][28][29][30]. In this method, the reference samples are usually thin films made of fluorescent organic dyes, such as 3-borylbithiophene derivatives [27][28][29][30] or rhodamine 6G (R6G) [1,13,14]. The thicknesses and emission profiles of the reference films must be spatially uniform at micro-scale dimensions to permit comparison with the local PL of micro-sized 1L-TMDs.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, they are undesirable for use as reference samples. Previously, 3-borylbithiophene derivatives have been used as reference films [28][29][30]; however, controlling the uniform dispersion of organic molecules in a matrix is technically difficult. Therefore, for the reliable measurement of the QY of 1L-TMDs, the method of preparing thin films containing uniformly dispersed organic dyes is still in high demand.…”

Section: Introductionmentioning

confidence: 99%

Measurement of Quantum Yields of Monolayer TMDs Using Dye-Dispersed PMMA Thin Films

et al. 2020

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In general, the quantum yields (QYs) of monolayer transition metal dichalcogenides (1L-TMDs) are low, typically less than 1% in their pristine state, significantly limiting their photonic applications. Many methods have been reported to increase the QYs of 1L-TMDs; however, the technical difficulties involved in the reliable estimation of these QYs have prevented the general assessment of these methods. Herein, we demonstrate the estimation of the QYs of 1L-TMDs using a poly methyl methacrylate (PMMA) thin film embedded with rhodamine 6G (R6G) as a reference specimen for measuring the QYs of 1L-TMDs. The PMMA/R6G composite films with thicknesses of 80 and 300 nm demonstrated spatially homogeneous emissions with the incorporation of well-dispersed R6G molecules, and may, therefore, be used as ideal reference specimens for the QY measurement of 1L-TMDs. Using our reference specimens, for which the QY ranged from 5.4% to 22.2% depending on the film thickness and R6G concentrations, we measured the QYs of the exfoliated or chemical vapor deposition (CVD)-grown 1L-WS2, -MoSe2, -MoS2, and -WSe2 TMDs. The convenient procedure proposed in this study for preparing the thin reference films and the simple protocol for the QY estimation of 1L-TMDs may enable accurate comparisons of the absolute QYs between the 1L-TMD samples, thereby enabling the development of a method to improve the QY of 1L-TMDs.

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Photoluminescence quantum yields for atomically thin-layered ReS2: Identification of indirect-bandgap semiconductors

Cited by 39 publications

References 44 publications

Interlayer charge transfer in ReS2/WS2 van der Waals heterostructures

Interlayer charge transfer in ReS2/WS2 van der Waals heterostructures

Two-dimensional ReS2 : Solution to the unresolved queries on its structure and inter-layer coupling leading to potential optical applications

Measurement of Quantum Yields of Monolayer TMDs Using Dye-Dispersed PMMA Thin Films

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