Near‐Unity Molecular Doping Efficiency in Monolayer MoS<sub>2</sub>

Yarali, Milad; Zhong, Yiren; Reed, Serrae N.; Wang, Juefan; Ulman, Kanchan; Charboneau, David J.; Curley, Julia B.; Hynek, David; Pondick, Joshua V.; Yazdani, Sajad; Hazari, Nilay; Quek, Su Ying; Wang, Hailiang; Judy, J.

doi:10.1002/aelm.202000873

Cited by 18 publications

(36 citation statements)

References 40 publications

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“…In principle, the charge transfer process at the WSe 2 /molecule interface is a complex problem that depends on multiple variables such as the relative frontier orbital levels, available density of states, and dielectric properties, all of which are considered in our calculations. Although our GGA level of theory is subject to slight limitations (i.e., the exact position of the frontier orbital levels and dynamic dielectric properties), [ 47–50 ] we can expect qualitative trends to be meaningful as shown in previous DFT studies [ 25,40,51,52 ] and our approaches are still relevant. From the vdW‐corrected DFT calculations, we obtained the planar‐averaged charge density profiles of the charge density difference

Δ ρ = ρ_{d o p e d - W S {normale}_{2}} - (ρ_{W S {normale}_{2}} + ρ_{d o p a n t})

along the c ‐axis for magic blue, Mo(tfd‐COCF 3 ) 3 , and F 4 ‐TCNQ as shown in Figure a–c.…”

Section: Resultsmentioning

confidence: 82%

Molecular Dopant‐Dependent Charge Transport in Surface‐Charge‐Transfer‐Doped Tungsten Diselenide Field Effect Transistors

et al. 2021

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The controllability of carrier density and major carrier type of transition metal dichalcogenides(TMDCs) is critical for electronic and optoelectronic device applications. To utilize doping in TMDC devices, it is important to understand the role of dopants in charge transport properties of TMDCs. Here, the effects of molecular doping on the charge transport properties of tungsten diselenide (WSe2) are investigated using three p‐type molecular dopants, 2,3,5,6‐tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane (F4‐TCNQ), tris(4‐bromophenyl)ammoniumyl hexachloroantimonate (magic blue), and molybdenum tris(1,2‐bis(trifluoromethyl)ethane‐1,2‐dithiolene) (Mo(tfd‐COCF3)3). The temperature‐dependent transport measurements show that the dopant counterions on WSe2 surface can induce Coulomb scattering in WSe2 channel and the degree of scattering is significantly dependent on the dopant. Furthermore, the quantitative analysis revealed that the amount of charge transfer between WSe2 and dopants is related to not only doping density, but also the contribution of each dopant ion toward Coulomb scattering. The first‐principles density functional theory calculations show that the amount of charge transfer is mainly determined by intrinsic properties of the dopant molecules such as relative frontier orbital positions and their spin configurations. The authors’ systematic investigation of the charge transport of doped TMDCs will be directly relevant for pursuing molecular routes for efficient and controllable doping in TMDC nanoelectronic devices.

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Δ ρ = ρ_{d o p e d - W S {normale}_{2}} - (ρ_{W S {normale}_{2}} + ρ_{d o p a n t})

along the c ‐axis for magic blue, Mo(tfd‐COCF 3 ) 3 , and F 4 ‐TCNQ as shown in Figure a–c.…”

Section: Resultsmentioning

confidence: 82%

Molecular Dopant‐Dependent Charge Transport in Surface‐Charge‐Transfer‐Doped Tungsten Diselenide Field Effect Transistors

et al. 2021

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“…However, after the TPE-4NO 2 doping treatment, the peak positions were shifted to lower binding energy, indicating a shift of the valence band toward the Fermi level, as expected to produce p-type doping. On the other hand, after the TPE-4OCH 3 doping treatment, the peak positions shifted to higher binding energy, demonstrating that the conduction band moves downward to the Fermi level, producing an n-type doping feature [ 33 , 34 , 35 ].…”

Section: Resultsmentioning

confidence: 99%

Surface Charge Transfer Doping of MoS2 Monolayer by Molecules with Aggregation-Induced Emission Effect

Sun

Liang

et al. 2022

Nanomaterials

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Surface charge transfer doping has attracted much attention in modulating the optical and electrical behavior of 2D transition metal dichalcogenides (TMDCs), where finding controllable and efficient dopants is crucial. Here, 1,1,2,2-tetraphenylethylene (TPE) derivative molecules with aggregation-induced emission (AIE) effect were selected as adjustable dopants. By designing nitro and methoxyl functional groups and surface coating, controlled p/n-type doping can be achieved on a chemical vapor deposition (CVD) grown monolayer, MoS2. We investigated the electron transfer behavior between these two dopants and MoS2 with fluorescence, Raman, X-ray photoelectron spectra and transient absorption spectra. 1,1,2,2-Tetrakis(4-nitrophenyl)ethane (TPE-4NO2) with a negative charge aggregation can be a donor to transfer electrons to MoS2, while 1,1,2,2-Tetrakis(4-methoxyphenyl)ethane (TPE-4OCH3) is the opposite and electron-accepting. Density functional theory calculations further explain and confirm these experimental results. This work shows a new way to select suitable dopants for TMDCs, which is beneficial for a wide range of applications in optoelectronic devices.

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“…Experimentally, electron doping can be achieved through electrostatic gating and surface molecular functionalization to induce the phase transition. [ 6,20 ] For instance, a monolayer 2H‐MoTe 2 undergoes a phase transition to 1T′ by ionic liquid gating at the critical doping concentration of 2.2 × 10 14 cm −2 . [ 21 ] For other group VI TMDCs whose energy differences between the 2H and 1T′ phase are larger than MoTe 2 , electron doping by gating and surface functionalization have not induced the 2H → 1T′ phase transition.…”

Section: Knowledge Gap In Current Understanding Of Phase Transition and Intercalationmentioning

confidence: 99%

Revisiting Intercalation‐Induced Phase Transitions in 2D Group VI Transition Metal Dichalcogenides

Wang

Judy

2021

Adv Energy and Sustain Res

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Intercalation of alkali metals is widely studied to introduce a structural phase transition from 2H to 1T′ in 2D group VI transition metal dichalcogenides (TMDCs). This highly efficient phase transition method has enabled an access to a library of phases with novel physical and chemical properties attractive for functional devices and electrochemical catalysis. However, despite numerous studies that have predicted that charge doping mainly contributes to the structural phase transition in the intercalation process, a mechanistic understanding of the phase transition at the atomic level has not been fully revealed. Furthermore, the coupled effects of strain and other intrinsic or extrinsic factors on the intercalation‐induced phase transition have not been quantitatively determined. Herein, the progress of the intercalation‐induced phase transition is briefly overviewed and the knowledge gaps in the current understanding of phase transition and intercalation in 2D TMDCs are highlighted. To fully gain the microscopic picture of the intercalation‐induced phase transition, in situ multimodal probes to monitor the real‐time structure−property relationship during intercalation are suggested. The proposed research directions further direct material scientists to efficiently engineer phase transition pathways in 2D materials to explore novel functional phases.

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Near‐Unity Molecular Doping Efficiency in Monolayer MoS₂

Cited by 18 publications

References 40 publications

Molecular Dopant‐Dependent Charge Transport in Surface‐Charge‐Transfer‐Doped Tungsten Diselenide Field Effect Transistors

Molecular Dopant‐Dependent Charge Transport in Surface‐Charge‐Transfer‐Doped Tungsten Diselenide Field Effect Transistors

Surface Charge Transfer Doping of MoS2 Monolayer by Molecules with Aggregation-Induced Emission Effect

Revisiting Intercalation‐Induced Phase Transitions in 2D Group VI Transition Metal Dichalcogenides

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Near‐Unity Molecular Doping Efficiency in Monolayer MoS2

Cited by 18 publications

References 40 publications

Molecular Dopant‐Dependent Charge Transport in Surface‐Charge‐Transfer‐Doped Tungsten Diselenide Field Effect Transistors

Molecular Dopant‐Dependent Charge Transport in Surface‐Charge‐Transfer‐Doped Tungsten Diselenide Field Effect Transistors

Surface Charge Transfer Doping of MoS2 Monolayer by Molecules with Aggregation-Induced Emission Effect

Revisiting Intercalation‐Induced Phase Transitions in 2D Group VI Transition Metal Dichalcogenides

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Near‐Unity Molecular Doping Efficiency in Monolayer MoS₂