Doped MoS2 Research Articles

Charge Transfer‐Induced SERS Enhancement of MoS2/Dopants Dependent on their Interaction Difference

Abstract2D transition metal dichalcogenide materials have attracted increasing attention as active surface‐enhanced Raman spectroscopy (SERS) platforms. In this study, the influence of n‐ and p‐type doping of exfoliated MoS2 (exMoS2) hybrids on the SERS performance is investigated, employing Rhodamine 6G (R6G) as a probe molecule. It is demonstrated that n‐doped exMoS2 hybrids (exMoS2 mixed with C60, graphene, and sodium dodecyl sulfate) exhibit enhanced SERS intensities, while p‐doping (exMoS2 mixed with TCNQ) resulted in inhibited SERS enhancement. A key discovery is the linear relationship between Raman enhancement of MoS2/dopant hybrids and the difference in their LUMO energy levels, which dictate the degree and direction of charge transfer. Interestingly, MC60‐4, a C60‐doped hybrid, deviates from the linear relationship, displaying remarkable SERS enhancement owing to its chemical interaction and unique Raman scattering activity. The findings provide critical insights into the SERS enhancement behavior of doped MoS2, facilitating precise tuning of SERS intensities by manipulating the MoS2 doping state.

Electronic Modulation of Doped MoS2 Nanosheets for Improved CO2 Sensing and Capture.

Transition-metal dichalcogenides (TMDs) are widely used in the gas sensing field, owing to their high surface-to-volume ratio enabled by the two-dimensional (2D) structure, adjustable band gap, and high electron transfer. However, it is challenging for TMD materials to realize superior CO2 sensing, due to their weak CO2 adsorption capacity. Herein, we predict through density functional theory (DFT) calculations that rare earth metal doping is an effective strategy to boost the CO2 sensing capability of TMDs. As a proof-of-concept, we investigate and find that the introduction of rare earth metal atoms (La, Ce, Pr, or Nd) can induce lattice strain and modulate the electronic properties of MoS2. When negative charges are injected in rare earth metal doped MoS2 (R-MoS2), the 5d or 4f orbital of the rare earth metal atom in R-MoS2 can produce a stronger orbital hybridization with 2p orbitals of C and O in CO2. Therefore, the CO2 adsorption is significantly enhanced and the charge transfer is facilitated for negatively charged R-MoS2. Moreover, negatively charged R-MoS2 exhibits an excellent CO2 selectivity. Our results indicate that the rare earth metal doping and electronic modulation in 2D materials may provide a new pathway for CO2 sensing and capture.

The Impact of Oxygen Content in O-Doped MoS2 on the Kinetics of Polysulfide Conversion in Li-S Batteries.

Polysulfide shuttle and sluggish sulfur redox kinetics remain key challenges in lithium-sulfur batteries. Previous researches have shown that introducing oxygen into transition metal sulfides helps to capture polysulfides and enhance their conversion kinetics. Based on this, further investigations are conducted to explore the impact of oxygen doping levels on the physical-chemical properties and electrocatalytic performance of MoS2. The findings reveal that MoS2 doped with high-content oxygen exhibits enhanced conductivity and polysulfides conversion kinetics compared to MoS2 with low-content oxygen doping, which can be attributed to the alteration of crystal structure from 2H-phase to the 1T-phase, the introduction of increased Li-O interactions, and the effect of defects resulting from high-oxygen doping. Consequently, the lithium-sulfur batteries using high-oxygen doped MoS2 as a catalyst deliver a high discharge capacity of 1015 mAh g-1 at 0.25C and maintain 78.5% capacity after 300 more cycles. Specifically, lithium-sulfur batteries employing paper-based electrodedemonstrate an areal capacity of 3.91 mAh cm-2 at 0.15C, even with sulfur loading of 4.1mg cm-2 and electrolyte of 6.7µL mg-1. These results indicate that oxygen doping levels can modify the properties of MoS2, and high-oxygen doped MoS2 shows promise as an efficient catalyst for lithium-sulfur batteries.

A high-performance TFN membrane prepared by a novel PE support layer, a polydopamine interlayer, and a doped MoS2 quantum dots@ZnO nanocomposites-incorporated polyamide active layer

Herein, thin film nanocomposite (TFN) membranes were prepared with excellent chemical stability and separation performance for organic solvent nanofiltration (OSN) applications. The support membrane was synthesized via a new approach, in which a blend of two immiscible polymers, i.e. high density polyethylene (HDPE)-polystyrene (PS), which were compatibilized with styrene-ethylene-butylene-styrene (SEBS), was prepared through mixing by a Brabender, followed by fabricating blend sheets through a hot press machine. The PE support was then prepared by extracting the PS/compatibilizer phase from the blend sheet. The hydrophilicity of the PE support membrane was considerably enhanced with a polydopamine (PDA) layer. Different nanoparticles including nanoflower (NF) ZnO, nanosphere (NS) ZnO, MoS2 Quantum dots-nanoflower ZnO nanocomposite (QDs@NF ZnO), and MoS2 Quantum dots-nanosphere ZnO nanocomposite (QDs@NS ZnO) were incorporated into the polyamide (PA) active layer of the membranes to enhance the performance of the TFN membranes. The separation performance of the TFN membranes was investigated for rejecting different dyes dissolved in methanol. Our results demonstrate outstanding separation performance, with a dye rejection of 99.6 %, 99.6 %, 99.8 %, and 99.9 % for methylene blue, crystal violet, rhodamine B, and methyl green, respectively. Additionally, the TFN membranes incorporated with QDs@NF ZnO nanoparticles showed great solvent resistance, with a methanol permeance up to 6.7 L/m2.h.bar after activation with dimethylformamide.

Stability of Vanadium Doped Transition Metal Dichalcogenides under Etching Atmosphere

Two‐dimensional (2D) transition metal dichalcogenides (TMDs) have attracted intensive interests for its unique electronic, optical, and thermal properties. Doping is necessary to expand the application. However, the stability of doped materials has been overlooked. This study focuses on the stability of monolayer‐doped MoS2 with different vanadium (V) concentrations. It provides a quantitative assessment of the etching results. Findings indicate that the stability of MoS2 under different etching atmospheres follows the series of lightly doped MoS2 (LD), pristine MoS2 (PR), moderately doped MoS2 (MD), and highly doped MoS2 (HD). Our research indicates that the stability of the material is linked to the bonding energy of cations and anions, as well as the amount of lattice distortion, which competes with one another. Low levels of V doping do not lead to significant lattice distortion, and the binding energy between sulfur (S) and V surpasses that of molybdenum (Mo), which is the primary factor. Excessive doping results in lattice distortion, which leads to a multitude of defects and a reduction in durability. This work is important for guiding the assessment of the reliability, the protection of degradation, and application scenarios of TMDs.This article is protected by copyright. All rights reserved.

Engineering surface state density of monolayer CVD grown 2D MoS2 for enhanced photodetector performance.

This study demonstrates the effect of nitrogen doping on the surface state densities (Nss) of monolayer MoS2 and its effect on the responsivity and the response time of the photodetector. Our experimental results shows that by doping monolayer MoS2 by nitrogen, the surface state (Nss) increases thereby increasing responsivity. The mathematical model included in the paper supports the relation of photocurrent gain and its dependency on trap level which states that the increasing the trap density increases the photocurrent gain and the same is observed experimentally. The experimental results at room temperature revealed that nitrogen doped MoS2 have a high NSS of 1.63 X 1013 states/m2/eV compared to undoped MoS2 of 4.2 x 1012 states/m2/eV. The increase in Nss in turn is the cause for rise in trap states which eventually increases the value of photo responsivity from 65.12 A/W (undoped MoS2) to 606.3 A/W (nitrogen doped MoS2). The response time calculated for undoped MoS2 was 0.85 sec and for doped MoS2 was 0.35 sec. Finally, to verify the dependence of surface states on the responsivity, the surface states were varied by varying temperature and it was observed that upon increment in temperature, the surface states decreases which causes the responsivity values also to decrease.

Tailoring the optoelectronic properties of monolayer BA2PbI4/MoS2 heterojunction through terminal variations and defect engineering

In light of the inherent challenge posed by the simultaneous pursuit of structural stability and favorable optoelectronic characteristics in two-dimensional organic-inorganic halide perovskites, the construction of heterojunctions emerges as a promising strategy for mitigating electronic deficiencies and enhancing overall performance. Furthermore, defect engineering stands as a commonly employed technique to fine-tune the photoelectric properties of materials. In this study, we systematically investigate the pivotal vacancy defects, namely VBA and VI, within the monolayer BA2PbI4/MoS2 heterojunction system, employing first-principles calculations. Our computational findings illuminate the conductivity of MoS2 can be modulated when it interfaces with distinct surface terminations of 2D BA2PbI4, thereby exerting influence over electron flow within MoS2. Additionally, we observe a progressive transformation of p-type doped MoS2 into a heavily doped material as the concentration of BA vacancy defects increases. To further optimize the optoelectronic properties, we strategically introduce the I vacancy (Pb-Pb dimer) defect, effectively transitioning the indirect bandgap heterojunction into a direct one. Our study underscores the profound impact of different surface terminations and defect configurations on the physical attributes of the heterojunction, offering valuable insights for the fabrication of high-performance photoelectric materials.

First principle study of the effect of doping on the optoelectronic properties of Cr-adsorbed MoS2.

This study explores, for the first time, using first principles, the impact of substitutional doping with boron (B), carbon (C), and nitrogen (N) on the adsorption of chromium (Cr) on monolayer MoS2. The effects of doping on the Cr adsorption behavior of MoS2 were investigated using four MoS2 systems, namely, pure, boron (B)-doped, carbon (C)-doped, and nitrogen (N)-doped, in order to gain an in-depth understanding of the mechanism of the effects of doping on the electronic structure and optical properties of Cr adsorbed by MoS2, to optimize the properties of MoS2, to explore new areas of application, and to promote the development of materials science. Four MoS2 adsorption systems of Cr adsorption on pure, B-doped, C-doped, and N-doped MoS2 were optimized, and the optimized results showed that the stable adsorption location of Cr on both pure and doped MoS2 was the hollow location at the top of the folded hexagon. The findings reveal that pure MoS2 has an adsorption effect on Cr, and doped elements B, C, and N can promote the adsorption of Cr on MoS2, and the strong and weak order of this promotion is B > C > N. In this paper, we use the CASTEP module in the simulation software Materials Studio to perform simulation calculations and analyses to optimize the simulation of Cr adsorption by MoS2 doped with B, C, and N atoms using the generalized gradient approximation (GGA) plane-wave pseudo-potential method (Perdew et al. Phys Rev Lett 77(18):3865-3968, 1996), as well as Perdew-Burke-Ernzerhof (PBE) generalized functionals (Segall et al. J Phys: Condens Matter 14(11):2717-2744, 2022). The convergence test reveals that it is more reasonable to set the K-point network to 3 × 3 × 1 and the truncation energy to 400 eV. In this paper, a 3 × 3 × 1 supercell structure with 18 S atoms and 9 Mo atoms is selected. The convergence value of the iteration accuracy is 1.0e - 5eV/atom, and all the atomic forces are less than 0.02eV/Å. Additionally, to prevent MoS2 interlayer interaction, a vacuum layer with a thickness of 18 Å is set in the C direction. The geometrical optimization of the model is performed first, and then the corresponding adsorption energies of the model and the nature of the electronic structure are analyzed.

A polarization-sensitive, high on/off ratio and self-powered photodetector based on Nb2CT x and Nd2CT x @MoS2

MXene two-dimensional materials have been widely used in energy storage, catalysis, sensing and other fields, Nb2C as a typical two-dimensional MXene material, its exploration in the field of optoelectronics is still in its infancy, especially Nb2C-based photodetectors are still to be developed. This paper demonstrates that two-dimensional films based on few-layer Nb2C have a photoelectric response in the wavelength range from visible to near-infrared. We have found that the light response performance can be easily adjusted by controlling the thickness of the spin-coated film, and that Nb2C photodetectors show great advantages in terms of wide bandwidth, polarization response, high switching ratio, etc. By adjusting the material concentration and sample thickness, the photocurrent can reach up to 330 nA, the switching ratio can reach 410, and the responsivity can reach 8.3 × 10−4 A W−1. In the polarization characteristic test, an extinction ratio of 7.6 can be obtained. By adjusting the content of that doped MoS2 quantum dot, the dark current can reach 7.6 × 10−13 A, and the switching ratio can reach 3 × 105, which can be increased by 700 times. The above results show that the few-layer Nb2C nanosheets can be used as optoelectronic detectors in the visible to near-infrared bands, which further broadens the application prospects of two-dimensional MXene.

In-situ methyl red doped MoS2 field effect transistor made by atomically thin MoS2 channel

Here we present the effects of Methyl Red (MR) doping on the electrical properties of the MoS2 field effect transistor (FET) in in-situ experimental system where the doping and electrical measurement are carried out in a single ultra-high vacuum chamber. A single-layered MoS2 flake was used as channel material for the FET preparation. N-type doping by MR was confirmed by the left shift of threshold voltage (Vth) and the surface vibrational change measured by Raman spectroscopy. The n-doping by MR is implied by the Fermi level shift towards greater binding energy with MR coverage, as proven by an X-ray photoelectron spectroscopy (XPS) measurement. It is estimated from XPS that the MoS2-FET device may detect the doping effect from the sub-monolayer MR. MR was detected on the MoS2 surface by the Time-of-Flight Secondary Ionization Mass Spectroscopy (ToF-SIMS). The findings may pave the way for innovations in electronic device design, with potential implications for fields ranging from nanoelectronics to sensor technology.

First-principles study of metals, metalloids and halogens doped monolayer MoSe2 to tune its electronic properties

Owing to their small band-gap characteristics, two-dimensional transition metal dichalcogenides (TMDCs) have garnered a lot of attention. Herein, we studied the electronic as well as structural properties of doped monolayered MoSe2 with different dopants at the selenium (Se) site employing the density functional theory (DFT) using generalized gradient approximation (GGA). To ascertain bonding nature electron localization function (ELF) was used and Phonon spectra computations were done for dynamical stability tests. We systematically explored the electronic properties of monolayer MoSe2 doped with X-atoms (X comprises of metals Li, Be, Al; metalloids B, Si; non-metals (NMs) C, N, P, O and the NM atoms belonging to halogen group (F, Cl). We compared our outcomes with available experimental and other calculated results in the literature. The appearance of impurity lines in the energy gap causes to diminish the band gaps of doped MoSe2. The change in doping site and dopant element results in a significant reduction in the bandgap of doped MoSe2. To gain more insight into the electronic properties of X-doped MoSe2 monolayer, the partial density of states (PDOS) of the dopants and neighbour Mo atoms are attached to the band structures. Our results give pleasing data regarding the optimization of bandgap which shows that halogen dopant provided n-type doping while the rest of the elements provided p-type doping in MoSe2, which helps to understand the electrical conductivity in addition to their utilization in semiconductor and other optoelectronic devices. We are optimistic that the findings in this work will help experimentalists to carry out their research on a real-world application, which will also widen the investigation of transition-metal dichalcogenides (TMDs) in other sectors.

A doping strategy to achieve synergistically tuned magnetic and dielectric properties in MoSe2 for broadband electromagnetic wave absorption

Advanced electromagnetic (EM) wave absorbing materials are essential to tackle the even-increasing EM interference and pollution. Conventional methods usually combine magnetic and dielectric components for optimized impedance matching and attenuation. It is, however, challenging to simultaneously tune magnetic and dielectric properties with one wane and the other wax by adjusting the ratio between the corresponding components. Here, simultaneous modulation of both magnetic and dielectric properties has been achieved via a doping strategy in MoSe2. On the one hand, significant room-temperature ferromagnetism could be induced through the generation and coupling of local magnetic moments of Mn2+. On the other hand, Mn doping also enhances the dielectric properties by promoting the formation of amorphous and 1T phase of doped MoSe2. The synergistic magnetic and dielectric effects give rise to optimal absorption performance with a minimum reflection loss (RLmin) of −54.57 dB and a wide effective absorption bandwidth (EAB) of 8.24 GHz at 2.00 mm. Such comprehensive performance surpasses the majority of the transition metal dichalcogenide (TMD)-based composites and is the best among all the single-component TMD absorbers. Consequently, the study sheds light on synergistic modulation of EM properties in single-component materials, providing prospective solutions in the design of magnetic and dielectric devices for EM wave absorption and other fields, such as sensing, information storing, and quantum computing.

Efficient Photocatalytic Degradation of Co Doped MoS2 Assembled by Nano-sheet and First-Principles Analysis

Efficient Photocatalytic Degradation of Co Doped MoS2 Assembled by Nano-sheet and First-Principles Analysis

Engineering the Local Atomic Configuration in 2H TMDs for Efficient Electrocatalytic Hydrogen Evolution.

The introduction of heteroatoms is a widely employed strategy for electrocatalysis of transition metal dichalcogenides (TMDs). This approach activates the inactive basal plane, effectively boosting the intrinsic catalytic activity. However, the effect of atomic configurations incorporated within the TMDs' lattice on catalytic activity is not thoroughly understood owing to the lack of controllable synthetic approaches for highly doped TMDs. In this study, we demonstrate a facile approach to realizing heavily doped MoS2 with a high doping concentration above 16% via intermediate-reaction-mediated chemical vapor deposition. As the V doping concentration increased, the incorporated V atoms coalesced in a manner that enabled both the basal plane activation and electrical conductivity enhancement of MoS2. This accelerated the kinetics of the hydrogen evolution reaction (HER) through the reduced Gibbs free energy of hydrogen adsorption, as evidenced by experimental and theoretical analyses. Consequently, the coalesced V-doped MoS2 exhibited superior HER performance, with an overpotential of 100 mV at 10 mA cm-2, surpassing the pristine and single-atom-doped counterparts. This study provides an intriguing pathway for engineering the atomic doping configuration of TMDs to develop efficient 2D nanomaterial-based electrocatalysts.

Engineering 2D MoS2 for Enhanced Selectivity and Sensitivity of Selected Green House Gases (CO2, CH4 and N2O): An ab initio Study

2D MoS2 has been identified as a potential material for greenhouse gas (CO2, N2O, and CH4) sensing, however, the underlying principles are not well understood yet such knowledge may offer optimization opportunities for the development of superior devices. Using ab initio Density Functional Theory approach, selected dopants X (X= Cl, O, P, and Se) were judiciously introduced on 2D MoS2 and the response of the modified monolayer to the various greenhouse gases analyzed. The results showed that when the gas molecules are introduced within the periphery of the dopant site, the gases become adsorbed on the dopant with interactions that are characteristic of physisorption due to moderate adsorption energies. Based on the magnitude of adsorption energies, Cl, P, and O doped 2D MoS2 were found to be sensitive and selective to CO2, N2O and CH4 gas molecules respectively. Further, charge transfer analysis of CO2, and N2O adsorbed on Cl and P doped 2D MoS2 monolayer respectively, showed that these gas molecules gain electrons from the doped 2D MoS2 monolayer during adsorption, while CH4 molecule loses electrons to O doped 2D MoS2 surface. In addition, CO2, N2O, and CH4 gas molecules are desorbed from the surfaces of Cl, P, and O doped 2D MoS2 at 432 K, 438 K and 298 K respectively, thus rendering the modified monolayer re-usable detection of greenhouse gases. Cl doped 2D MoS2 monolayer showed superior performance in CO2 detection due to its fast recovery time and moderate thermal treatment temperature.Our results reveal that the competitive adsorption at the X doped 2D MoS2 surfaces between the analyte and the greenhouse gas present in the atmosphere induces a switching in surface conductance that can be related to the greenhouse gases concentration and can be detected electronically, thus disclosing the sensing mechanism and optimization route that can guide future experimental studies.

Synthesis of Gadolinium-Doped Molybdenum Diselenide Nanospheres for Ultrasensitive Electrochemical Determination of Essential Amino Acid in Human Serum and Milk Samples

The electrocatalytic activity and electronic conductivity of 2D transition metal chalcogenides are usually enhanced by as follows the ideal strategy such as doping or substitution heterogeneous atoms. Here, a rare Earth metal ion of gadolinium (Gd3+) was doped with MoSe2 and synthesized through the hydrothermal method. The morphology and nanostructure of Gd3+ with MoSe2 spheres were analyzed under X-ray diffraction, Fourier-transform infrared spectroscopy, X-ray photoelectron, High-resolution transmission electron microscopy analysis, Field emission scanning electron microscopy, and energy-dispersive spectroscopy. Furthermore, the Gd3+ doped MoSe2 sphere modified glassy carbon electrode (Gd@MoSe2/GCE) was used for the sensing of tryptophan. The Gd@MoSe2 modified GCE shows remarkable sensing performance of tryptophan resulting in a linear range (20 nM–220 μM) with a low detection limit (6.7 nM). Under the optimal condition, the developed electrochemical sensor was successfully used to determine tryptophan (TRP) in blood serum and milk samples. The electrochemical biosensing results suggest that the doping of the Gd3+ doped MoSe2 sensor is a promising electrocatalyst in biological and food samples.

In situ formation of spherical MoS2 particles on high-entropy alloy coating for low friction

Introductionof lubricant phase into thermally sprayed coating while avoids high-temperature ablation is still a challenge. Here, vacuum impregnation and hydrothermal reaction, acted as a post-treatment process, was applied to synthesize MoS2 phase on and within high-entropy alloy (HEA) coating. The as-synthesized MoS2 phase with high purity and spherical shape distributed in the pores and finally formed a thin layer on coating surface. Compared to the single HEA coating, coefficient of friction (COF) and wear rate (Q) of the HEA/MoS2 composite coatings possessed a significantly reduction, i.e 87.2% and 75.6% reduction in COF and Q at 2 N, respectively. Besides, owing to the formation of lubricating film during the sliding process, the composite coating had a more stable sliding process. At the same time, the doped MoS2 played a positive role in reducing abrasive- and adhesive wears for both coating and coupling ball. Since the lubricating film can be continuously replenished and repaired, the HEA/MoS2 self-lubricating coatings maintained a good chemical stability and provided a relatively good wear properties.

Dipole doping effect in MoS2 field effect transistors based on phase transition of ferroelectric polymer dopant

Molybdenum disulfide (MoS2) has great potential for next-generation electronic devices. On the other hand, stable doping methods are required to adjust its physical properties so MoS2 can be utilized in practical applications, such as transistors and photodetectors. On the other hand, a conventional doping method based on ion implantation is incompatible with 2D MoS2 because of the damage to the lattice structures of MoS2. This paper presents an n-type doping method for MoS2 field-effect transistors (FETs) using a poly (vinylidene fluoride-co-trifluoroethylene) (P (VDF-TrFE)) and polar polymer. The dipole moment of P (VDF-TrFE) provides n-type doping on MoS2 FETs. The polar phase formation in dopant films enhances the doping effects, and the relationship between phase transition and n-type doping states was investigated using optical and electrical characterization methods. Under the optimal doping conditions, the doped MoS2 FET achieved an improved field effect mobility of 34.4 cm2 V−1s–1, a negative shift in the threshold voltage by −25.6 V, and a high on-current of 21 μA compared to the pristine MoS2 FET.

Neodymium doping MoS2 nanostructures with remarkable surface-enhanced Raman scattering activity

In recent years, the study of surface-enhanced Raman scattering (SERS) substrate on semiconductors has greatly broadened the application of SERS technology in different fields. Developing new practical semiconductor SERS substrates materials is still important work. Here, different concentrations of Nd-doped MoS2 were synthesized by a simple hydrothermal method. Compared with pure MoS2, doping Nd successfully enhanced the SERS signal. The Enhancement factor (EF) of the 2 at% Nd-doped MoS2 is up to ∼1.29 × 106 due to the energy level transition and charge transfer effect. High sensitivity SERS detection of bilirubin, dipterex, and bisphenol A (BPA) was realized, and the lowest detection concentration was 10−8 M. Moreover, 2 at% Nd doped MoS2 as SERS substrate can realize high sensitivity SERS detection of bilirubin, dipterex and bisphenol A (BPA), and the limit of detection (LOD) is 10−8 M, 10−9 M, and 10−9 M, respectively. Furthermore, 2 at% Nd-doped MoS2 SERS substrate has high uniformity and excellent reproducibility, which is beneficial for practical applications. This work not only provides an efficient technique to get sensitive, stable, and low-cost SERS substrates but also advantageous for many application scenarios.

Quantum Dynamics of Attractive and Repulsive Polarons in a Doped MoSe2 Monolayer

When mobile impurities are introduced and coupled to a Fermi sea, new quasiparticles known as Fermi polarons are formed. There are two interesting, yet drastically different regimes of the Fermi polaron problem: (i) the attractive polaron (AP) branch connected to pairing phenomena spanning the crossover from BCS superfluidity to the Bose-Einstein condensation of molecules and (ii) the repulsive branch (RP), which underlies the physics responsible for Stoner’s itinerant ferromagnetism. Here, we study Fermi polarons in two-dimensional systems, where many questions and debates regarding their nature persist. The model system we investigate is a doped MoSe2 monolayer. We find the observed AP-RP energy splitting and the quantum dynamics of attractive polarons agree with the predictions of polaron theory. As the doping density increases, the quantum dephasing of the attractive polarons remains constant, indicative of stable quasiparticles, while the repulsive polaron dephasing rate increases nearly quadratically. The dynamics of Fermi polarons are of critical importance for understanding the pairing and magnetic instabilities that lead to the formation of rich quantum phases found in a wide range of physical systems including nuclei, cold atomic gases, and solids.Received 17 July 2022Revised 12 November 2022Accepted 23 January 2023DOI:https://doi.org/10.1103/PhysRevX.13.011029Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasFermionsOptical & microwave phenomenaPolaronsQuantum coherence & coherence measuresPhysical SystemsTransition metal dichalcogenidesTechniquesFour-wave mixingCondensed Matter, Materials & Applied Physics