Exciton Kinetics, Quantum Efficiency, and Efficiency Droop of Monolayer MoS<sub>2</sub> Light-Emitting Devices

Salehzadeh, O.; Tran, Nghi H.; Liu, X.; Shih, I.; Mi, Zetian

doi:10.1021/nl5017283

Cited by 161 publications

(128 citation statements)

References 38 publications

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“…Power-dependent PL decay was conducted with pulse laser powers 0.19, 0.38, 0.77, and 1.15 mW, and the same fitting process was performed to obtain the carrier lifetimes to be 222, 219, 232, and 211 ps, respectively, showing no significant power dependence. The power-dependent carrier lifetime measurement results of the monolayer phosphorene sample differ from the results of other TMD semiconductors, which show a decreasing carrier lifetime with increase in excitation laser power 35 . This independence of carrier lifetime of our monolayer phosphorene samples suggests that higher order processes such as exciton-exciton annihilation were negligible for the excitation power employed in our experiments 34 .…”

Section: Excitons and Trions In Monolayer Phosphorenecontrasting

confidence: 83%

Optical tuning of exciton and trion emissions in monolayer phosphorene

et al. 2015

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Monolayer phosphorene provides a unique two-dimensional (2D) platform to investigate the fundamental dynamics of excitons and trions (charged excitons) in reduced dimensions. However, owing to its high instability, unambiguous identification of monolayer phosphorene has been elusive. Consequently, many important fundamental properties, such as exciton dynamics, remain underexplored. We report a rapid, noninvasive, and highly accurate approach based on optical interferometry to determine the layer number of phosphorene, and confirm the results with reliable photoluminescence measurements. Furthermore, we successfully probed the dynamics of excitons and trions in monolayer phosphorene by controlling the photo-carrier injection in a relatively low excitation power range. Based on our measured optical gap and the previously measured electronic energy gap, we determined the exciton binding energy to be ,0.3 eV for the monolayer phosphorene on SiO 2 /Si substrate, which agrees well with theoretical predictions. A huge trion binding energy of ,100 meV was first observed in monolayer phosphorene, which is around five times higher than that in transition metal dichalcogenide (TMD) monolayer semiconductor, such as MoS 2 . The carrier lifetime of exciton emission in monolayer phosphorene was measured to be ,220 ps, which is comparable to those in other 2D TMD semiconductors. Our results open new avenues for exploring fundamental phenomena and novel optoelectronic applications using monolayer phosphorene. Keywords: exciton; monolayer phosphorene; optical injection; two-dimensional materials INTRODUCTION Phosphorene is a recently developed two-dimensional (2D) material that has attracted tremendous attention owing to its unique anisotropic manner 1-6 , layer-dependent direct band gaps 7,8 , and quasi-onedimensional (1D) excitonic nature 9,10 , which are all in drastic contrast with the properties of other 2D materials, such as graphene 11 and transition metal dichalcogenide (TMD) semiconductors [12][13][14] . Monolayer phosphorene has been of particular interest in exploring technological applications and investigating fundamental phenomena, such as 2D quantum confinement and many-body interactions 9,15 . However, such unique 2D materials are unstable in ambient conditions and degrade quickly 8,16 . Particularly, monolayer phosphorene is expected to be much less stable than few-layer phosphorene 16 , hence making its identification and characterization extremely challenging. There is a huge controversy on the identification of very few-layer (one or two layers) phosphorene and thus on their properties [16][17][18] . This controversy was primarily due to the lack of a robust experimental technique to precisely identify the monolayer phosphorene. Consequently, many important fundamental properties of monolayer phosphorene, such as its excitonic nature, remain elusive. In this study, we propose and implement a rapid, noninvasive,

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Section: Excitons and Trions In Monolayer Phosphorenecontrasting

confidence: 83%

Optical tuning of exciton and trion emissions in monolayer phosphorene

et al. 2015

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“…10,11 Recently, signatures of a strong exciton-phonon interaction have been observed, 12,13 such as the preservation of valley coherence in double-resonant Raman scattering, 14 trion to exciton luminescence upconversion in monolayer WSe 2 assisted by A ′ 1 phonons, 15 and exciton enhanced anti-Stokes shifts in few layer MoTe 2 . 16 Despite a few theoretical proposals on the role of optical phonons in exciton dynamics, [17][18][19] and several experimental studies on phonon-limited exciton relaxation, [20][21][22] the details behind how and which phonons impact metrics such as the formation and relaxation of excitons remains largely unexplored. This knowledge is important for interpreting a wide range of 2D exciton phenomena and for exploring the potential of exciton-based 2D optoelectronics.…”

Section: Introductionmentioning

confidence: 99%

Phonon-assisted oscillatory exciton dynamics in monolayer MoSe2

Chow

Jones

et al. 2017

npj 2D Mater Appl

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In monolayer semiconductor transition metal dichalcogenides, the exciton-phonon interaction strongly affects the photocarrier dynamics. Here, we report on an unusual oscillatory enhancement of the neutral exciton photoluminescence with the excitation laser frequency in monolayer MoSe 2 . The frequency of oscillation matches that of the M-point longitudinal acoustic phonon, LA(M), suggesting the significance of zone-edge acoustic phonons and hence the deformation potential in exciton-phonon coupling in MoSe 2 . Moreover, oscillatory behavior is observed in the steady-state emission linewidth and in time-resolved PLE data, which reveals variation with excitation energy in the exciton lifetime. These results clearly expose the key role played by phonons in the exciton formation and relaxation dynamics of two-dimensional van der Waals semiconductors.

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“…For monolayer MoS 2 on SiO 2 substrates, the non-radiative decay time is~70 ps and the spontaneous emission lifetime is 10 ns, as estimated at room temperature [234,235].…”

Section: Lasersmentioning

confidence: 86%

Recent Advances in Electronic and Optoelectronic Devices Based on Two-Dimensional Transition Metal Dichalcogenides

Zhang

Yap

2017

Electronics

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Two-dimensional transition metal dichalcogenides (2D TMDCs) offer several attractive features for use in next-generation electronic and optoelectronic devices. Device applications of TMDCs have gained much research interest, and significant advancement has been recorded. In this review, the overall research advancement in electronic and optoelectronic devices based on TMDCs are summarized and discussed. In particular, we focus on evaluating field effect transistors (FETs), photovoltaic cells, light-emitting diodes (LEDs), photodetectors, lasers, and integrated circuits (ICs) using TMDCs.

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Exciton Kinetics, Quantum Efficiency, and Efficiency Droop of Monolayer MoS₂ Light-Emitting Devices

Cited by 161 publications

References 38 publications

Optical tuning of exciton and trion emissions in monolayer phosphorene

Optical tuning of exciton and trion emissions in monolayer phosphorene

Phonon-assisted oscillatory exciton dynamics in monolayer MoSe2

Recent Advances in Electronic and Optoelectronic Devices Based on Two-Dimensional Transition Metal Dichalcogenides

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Exciton Kinetics, Quantum Efficiency, and Efficiency Droop of Monolayer MoS2 Light-Emitting Devices

Cited by 161 publications

References 38 publications

Optical tuning of exciton and trion emissions in monolayer phosphorene

Optical tuning of exciton and trion emissions in monolayer phosphorene

Phonon-assisted oscillatory exciton dynamics in monolayer MoSe2

Recent Advances in Electronic and Optoelectronic Devices Based on Two-Dimensional Transition Metal Dichalcogenides

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Exciton Kinetics, Quantum Efficiency, and Efficiency Droop of Monolayer MoS₂ Light-Emitting Devices