Top Of Band Research Articles

Длинноволновый край фундаментального поглощения кристаллов боратов лития LiB-=SUB=-3-=/SUB=-O-=SUB=-5-=/SUB=- и Li-=SUB=-2-=/SUB=-B-=SUB=-4-=/SUB=-O-=SUB=-7-=/SUB=-

We have carried out an experimental study of the VUV edge of the optical host absorption of lithium borate crystals LiB3O5 (LBO) and Li2B4O7 (LTB). The transmission (T = 293 K) and absorption (T = 80, 293 K) spectra are studied, the short-wavelength boundary of the transparency band (cutoff wavelength) and the energy position of the edge are determined. fundamental absorption at which the absorption coefficient is k = 50 cm-1. The transmission (T = 293 K) and absorption (T = 80, 293 K) spectra were studied, the short-wavelength edge of the transparency band (cutoff wavelength) and the energy position of the edge fundamental absorption at which the absorption coefficient k = 50 cm-1 were determined. The absorption edge temperature shift coefficient −(3–4.7)·10-4 eV/K was determined. The dependence of the absorption edge parameters of oriented LBO ⊥ Y and LBO ⊥ X crystals has been studied. Based on low-temperature reflection spectra (T = 10 K, θ = 17◦, E = 4–32 eV) the Kramers – Kronig method was used to calculate the spectra of optical constants: refractive index (n) and absorption index (k), real (ε1) and imaginary (ε2) parts of the complex permittivity, as well as the absorption coefficient μ. The lowest energy peak, due to electronic transitions from the top of the valence band to the states of the bottom of the conduction band, was studied in the ε2(E) spectrum, the thresholds for interband transitions were determined (Eg at T = 10 K): 8.5–8.6 eV (LBO ⊥ Y), 8.6–8.7 eV (LBO ⊥ X) and 8.8–8.9 eV (LTB). The origin of the fundamental absorption edge of lithium borates is discussed.

A Low-Wavelength Host Absorption Edge of Cesium-Lithium Borate CsLiB-=SUB=-6-=/SUB=-O-=SUB=-10-=/SUB=-

We have carried out an experimental study of the VUV edge of the optical host absorption of cesium-lithium borate crystals CsLiB6O10 (CLBO). The transmission (T=293 K) and absorption (T = 80, 293 K) spectra were studied, the short-wavelength edge of the transparency band (cutoff wavelength) and the energy position of the edge fundamental absorption at which the absorption coefficient k=50 cm-1 were determined. The absorption edge temperature shift coefficient -5.5·10-4 eV/K was determined. Based on low-temperature reflection spectra (T=10 K, theta=17o, E=7-30 eV) the Kramers-Kronig method was used to calculate the spectra of optical constants: refractive index (n) and absorption index (k), real (ε1) and imaginary (ε2) parts of the complex permittivity , as well as the absorption coefficient μ. The lowest energy peak, due to electronic transitions from the top of the valence band to the states of the bottom of the conduction band, was studied in the ε2(E) spectrum, the thresholds for interband transitions were determined Eg=7.95 eV. The origin of the fundamental absorption edge of cesium-lithium borate is discussed. Keywords:: Cesium-lithium borate CsLiB6O10 (CLBO), host absorption edge, optical properties.

Длинноволновый край фундаментального поглощения кристаллов цезий-литиевого бората CsLiB-=SUB=-6-=/SUB=-O-=SUB=-10-=/SUB=-

We have carried out an experimental study of the VUV edge of the optical host absorption of cesium-lithium borate crystals CsLiB6O10 (CLBO). The transmission (T = 293K) and absorption (T = 80, 293 K) spectra are studied, the short-wavelength boundary of the transparency band (cutoff wavelength) and the energy position of the edge are determined. fundamental absorption at which the absorption coefficient is k = 50 cm−1. The transmission (T = 293 K) and absorption (T = 80, 293 K) spectra were studied, the short-wavelength edge of the transparency band (cutoff wavelength) and the energy position of the edge fundamental absorption at which the absorption coefficient k = 50cm−1 were determined. The absorption edge temperature shift coefficient −(3–4.7)·10−4 eV/K was determined. The dependence of the absorption edge parameters of oriented LBO⊥ X and LBO⊥ Y crystals has been studied. Based on low-temperature reflection spectra (T =10K, θ =17◦, E = 4–32 eV ) the Kramers –Kronig method was used to calculate the spectra of optical constants: refractive index (n) and absorption index (k), real (ε1) and imaginary (ε2) parts of the complex permittivity , as well as the absorption coefficient μ. The lowest energy peak, due to electronic transitions from the top of the valence band to the states of the bottom of the conduction band, was studied in the ε2(E) spectrum, the thresholds for interband transitions were determined (Eg at T = 10K): 7.95 eV. The origin of the fundamental absorption edge of cesium-lithium borate is discussed.

Application of Fe-Based Amorphous Alloy in Industrial Wastewater Treatment: A Review

Amorphous alloy (MGs) is a solid alloy with disordered atomic accumulation obtained by ultra-rapid solidification of alloy melt. The atom deviates from the equilibrium position and is in metastable state. Up to now, a large number of MGs have been applied to the treatment of dye and heavy metal contaminated wastewater and ideal experimental results have been obtained. However, there is no literature to systematically summarize the chemical reaction and degradation mechanism in the process of degradation. On the basis of reviewing the classification, application, and synthesis of MGs, this paper introduces in detail the chemical reactions such as decolorization, mineralization, and ion leaching of Fe-based amorphous alloy (Fe-MGs) in the degradation of organic and inorganic salt wastewater through direct reduction or advanced oxidation mechanism. Compared with crystalline materials, the higher reaction rate of Fe-MGs can be attributed to lower activation energy, negative redox potential, loose product layer, and band structure with downward shift of valence band top. Finally, some suggestions and prospects are put forward for the limitations and research prospects of MGs in the environmental field, which provides a new idea for the synthesis of new environmental functional materials.

Helical symmetry breaking and quantum anomaly in massive Dirac fermions

Helical symmetry of massive Dirac fermions is broken explicitly in the presence of electric and magnetic fields. Here we present two equations for the divergence of helical and axial-vector currents following the Jackiw-Johnson approach to the anomaly of the neutral axial vector current. We discover the contribution from the helical symmetry breaking is attributed to the occupancy of the two states at the top of the valence band and the bottom of the conduction band. The explicit symmetry breaking fully cancels the anomalous correction from the quantum fluctuation in the band gap. The chiral anomaly can be derived from the helical symmetry breaking. It provides an alternative route to understand the chiral anomaly from the point of view of the helical symmetry breaking. The pertinent physical consequences in condensed matter are the helical magnetic effect which means a charge current circulating at the direction of the magnetic field, and the mass-dependent positive longitudinal magnetoconductivity as a transport signature. The discovery not only reflects anomalous magneto-transport properties of massive Dirac materials but also reveals the close relation between the helical symmetry breaking and the physics of chiral anomaly in quantum field theory and high energy physics.

Simultaneous Dirac-like Cones at Two Energy States in Tunable Phononic Crystals: An Analytical and Numerical Study

Simultaneous occurrence of Dirac-like cones at the center of the Brillouin zone (Γ) at two different energy states is termed Dual-Dirac-like cones (DDC) in this article. The occurrence of DDC is a rare phenomenon. Thus, the generation of multiple Dirac-like cones at the center of the Brillouin zone is usually non-manipulative and poses a challenge to achieve through traditional accidental degeneracy. However, if predictively created, DDC will have multiple engineering applications with acoustics and vibration. Thus, the possibilities of creating DDC have been identified herein using a simple square periodic array of tunable square phononic crystals (PnCs) in air media. It was found that antisymmetric deaf bands may play critical roles in tracking the DDC. Hence, pivoting on the deaf bands at two different energy states, an optimized tuning parameter was found to achieve Dirac-like cones at two distinct frequency states, simultaneously. Orthogonal wave transport identified as key Dirac phenomena was achieved at two frequencies, herein. It was identified that beyond the Dirac-like cone, the Dirac phenomena remain dominant when a doubly degenerated state created by a top band with positive curvature and a near-flat deaf band are lifted from a bottom band with negative curvature. Utilizing a mechanism of rotating the PnCs near a fixed deaf band, frequencies are tracked to form the DDC, and orthogonal wave transport is demonstrated. Exploiting the dispersion behavior, unique acoustic phenomena, such as ballistic wave transmission, pseudo diffusion and acoustic cloaking are also demonstrated at the Dirac frequencies using numerical simulation. The proposed tunable acoustic PnCs will have important applications in acoustic and ultrasonic imaging, waveguiding and even acoustic computing.

Large valley polarization in a novel two-dimensional semiconductor H-ZrX2 (X = Cl, Br, I)

Inspired by the new progress in the research field of two-dimensional valleytronics materials, we propose a new class of transition metal halides, i.e. H-ZrX2 (X = Cl, Br, I), and investigated their valleytronics properties under the first-principles calculations. It harbors the spin-valley coupling at K and K′ points in the top of valence band, in which the valley spin splitting of ZrI2 can reach up to 115 meV. By carrying out the strain engineering, the valley spin splitting and Berry curvature can be effectively tuned. The long-sought valley polarization reaches up to 108 meV by doping Cr atom, which corresponds to the large Zeeman magnetic field of 778 T. Furthermore, the valley polarization in ZrX2 can be lineally adjusted or flipped by manipulating the magnetization orientation of the doped magnetic atoms. All the results demonstrate the well-founded application prospects of single-layer ZrX2, which can be considered as great candidate for the development of valleytronics and spintronics.

Effect of the Type of Heterostructures on Photostimulated Alteration of the Surface Hydrophilicity: TiO2/BiVO4 vs. ZnO/BiVO4 Planar Heterostructured Coatings

Here, we report the results of comparative studies of the photostimulated hydrophilic behavior of heterostructured TiO2/BiVO4 and ZnO/BiVO4, and monocomponent TiO2 and ZnO nanocoating surfaces. The chemical composition and morphology of the synthesized nanocoatings were characterized by XPS, SEM, and AFM methods. The electronic energy structure of the heterostructure components (band gap, top of the valence band, bottom of the conduction band, and Fermi level position) was determined on the basis of experimental results obtained by XPS, UV-V absorption spectroscopy and Kelvin probe methods. According to their electronic energy structure, the ZnO/BiVO4 and TiO2/BiVO4 heterostructures correspond to type I and type II heterostructures, respectively. The difference in the type of heterostructures causes the difference in the charge transfer behavior at heterojunctions: the type II TiO2/BiVO4 heterostructure favors and the type I ZnO/BiVO4 heterostructure prevents the photogenerated hole transfer from BiVO4 to the outer layer of the corresponding metal oxide. The results of the comparative studies show that the interaction of the photogenerated holes with surface hydroxy-hydrated multilayers is responsible for the superhydrophilic surface conversion accompanying the increase of the surface free energy and work function. The formation of the type II heterostructure leads to the spectral sensitization of the photostimulated surface superhydrophilic conversion.

First-Principles Calculation of Conductivity of Ce-C Codoped SnO2 Contacts

The contact is the core element of the vacuum interrupter of the mechanical DC circuit breaker. The electrical conductivity and welding resistance of the material directly affect its stability and reliability. AgSnO2 contact material has low resistivity, welding resistance, and so on. This material occupies an important position of the circuit breaker contact material. This research is based on the first-principles analysis method of density functional theory. The article calculated the lattice constant, enthalpy change, energy band, electronic density of state, charge density distribution, population, and conductivity of Ce, C single-doped, and Ce-C codoped SnO2 systems. The results show that Ce, C single doping, and Ce-C codoping all increase the cell volume and lattice constant. When the elements are codoped, the enthalpy change is the largest, and the thermal stability is the best. It has the smallest bandgap, the most impurity energy levels, and the least energy required for electronic transitions. The 4f orbital electrons of the Ce atom and the 2p orbital electrons of C are the sources of impurity energy near the Fermi level. When the elements are codoped, more impurity energy levels are generated at the bottom of the conduction band and the top of the valence band. Its bandgap is reduced so conductivity is improved. From the charge density and population analysis, the number of free electrons of Ce atoms and C atoms is redistributed after codoping. It forms a Ce-C covalent bond to further increase the degree of commonality of electrons and enhance the metallicity. The conductivity analysis shows that both single-doped and codoped conductivity have been improved. When the elements are codoped, the conductivity is the largest, and the conductivity is the best.

Synthesis and photocatalytic performance of BiOCl/graphene composite with tight interfacial contact and highly exposed (001) facets

AbstractThe BiOCl/graphene composite was synthesized by vapor‐thermal method. The morphologies, structures, chemical states, and optical properties of the samples were systematically characterized. The visible light catalytic activity of the composite was studied by degrading methylene blue (MB). The results show that the sample obtained with 300‐mg BiCl3 and 1‐mg graphene (named Bi300GP1) forms Bi–C bond, has highly exposed (001) facets, forms a tight contact between BiOCl and graphene, and has more electron transfer channels, which effectively promoted the separation and migration of photoexcited carriers. In addition, the introduction of electronic states near the top of the valence band improved the visible light absorption of the sample, and the degradation rate of MB was the highest, which was increased from 76.64% to 98.12%. Meanwhile, it was confirmed by the ESR test that ·O2− played a major role in the photocatalytic degradation process.

Insight into the optical absorption and luminescent properties due to the presence of Pr4+ in Pr-doped Y2O3

Powder samples of undoped and Pr-doped Y2O3 are synthesized by the reverse precipitation method and annealed at 1000 °C for 1 h. X-ray diffraction patterns confirm the presence of the well-known Y2O3 cubic phase. The optical properties of the compounds are characterized by diffuse reflectance and photoluminescence spectroscopies. The presence of a huge absorption band in the Pr-doped samples is attributed to the presence of Pr4+, but also emission and excitation luminescent spectra reveal the existence of Pr3+. To explain the origin of the broad absorption band, it is made use of an approach formulated decades ago based on the assumption that ligand-to-metal charge transfer states O2−/- → Pr4+/3+ are involved. To implement this approach, a deconvolution of the absorption spectrum, following a judicious conjecture based on phenomenological methods in which each deconvolution's component is associated with a transition from the top of the valence band, mainly O-2p in character, to each of the Pr3+f-f states, or from the Pr3+-3H4 ground state to one of its d states, is performed. Our results match consistently with those energies calculated from a vacuum referred binding energy diagram, allowing to rationalize the presence of a huge absorption band as well as to explain the absence of the emission coming from the most energetic Pr3+ electronic transitions when Pr4+ is present in Pr-doped Y2O3.

Development of p-i-n radiation detectors based on semi-insulating 4H-SiC substrate via dual-face ion implantation

To explore the potential of semi-insulating (SI) SiC substrate for radiation detector applications, p-i-n diodes with thick depletion layers are fabricated by using a dual-face ion implantation technique on SI 4H-SiC substrate. The Poole-Frenkel (P-F) emission is found responsible for the reverse leakage current transport of the p-i-n diode at elevated temperatures. The derived emission barrier height is likely induced by the residual boron-related shallow-level states, which are located ∼ 0.3 eV above the top of the valence band. Detection tests of α-particles are performed on each side of the p-i-n detector to determine the location of the depleted region, which reveals weak p-type conduction of the SI 4H-SiC substrate after high temperature post-implantation annealing. The energy resolution of the detector operating in photovoltaic mode is ∼ 4.3%, which would degrade at higher biases. The saturated charge collection efficiency (CCE) of ∼ 99% for detection of 5.48 MeV α-particles is obtained as reverse bias exceeds 80 V.

Bimetallic superalkali substitution in the CsPbBr3 perovskite: Pseudocubic phases and tunable bandgap.

Perovskites attract attention as efficient light absorbers for solar cells due to their high-power conversion efficiency (up to 24%). The high photoelectric conversion efficiency is greatly affected by a suitable band structure. Cation substitution can be an effective approach to tune the electronic band structure of lead halide perovskites. In this work, superalkali cations were introduced to replace the Cs+ cation in the CsPbBr3 material. The bimetallic superalkalis (LiMg, NaMg, LiCa, and NaCa) were inserted since they are structurally simple systems and have a strong tendency to lose one electron to achieve a closed-shell cation. The cation substitution in the lead halide perovskite leads to changes in the shape of both valence and conduction bands compared to CsPbBr3. Introducing superalkali cations produces extra electronic states close to the Fermi level, which arise from the formation of alkali earth metal states at the top of the valence band. Our first-principles computations reveal that bimetallic superalkali substitution decreases the bandgap of the perovskite. The bandgaps of MgLi-PbBr3 (1.35eV) and MgNa-PbBr3 (1.06eV) are lower than the bandgap of CsPbBr3 (2.48eV) and within the optimal bandgap (i.e., 1.1-1.4eV) for single-junction solar cells. Thus, the MgLi-PbBr3 and MgNa-PbBr3 inorganic perovskites are promising candidates for high-efficiency solar cells.

Revisiting the Charge Transfer State in Tetravalent Lanthanide Doped Oxides: Up to Date Phenomenological Description

The coloring of oxides doped with Ln4+ has been the subject of much scientific research related to its application as pigments. However, until now, a rational explanation of this phenomenon had not been presented. Here is shown a scheme from a phenomenological perspective, that allows us to rationalize the experimental observations in the optical absorption spectra of Ln-doped (Ln = Ce, Pr and Tb) Y2O3 and Y4Zr3O12. This analysis was based on the explanation of the ligand-to-metal charge transfer (LMCT) O2−/− → Eu3+/2+ state in Eu-doped oxides. In this sense, Eu-doped Y2O3 and Y4Zr3O12 characterization is also presented. Features in the absorption spectra of these materials confirm the presence of Ce4+, Pr4+ and Tb4+, and the photoluminescent spectra their respective trivalent oxidation states. To demonstrate the contribution of multiple LMCT O2−/− → Ln4+/3+ states to the absorption spectra of compounds, Gaussian deconvolutions were performed. Maxima of Gaussian peak profiles were guessed from a vacuum referred binding energy diagram. The initial state for each LMCT O2−/− → Ln4+/3+ is always the top of the valence band, while the final ones correspond to some Ln3+ f state. Additional required peaks to reach adequate fittings were assigned to IVCT Ln3+/4+ and f-d Ln3+ states.

Band gap bowing and spectral width of Ga[formula omitted]In[formula omitted]N alloys for modelling light emitting diodes

Ga(1−x)InxN alloys, widely employed to produce light-emitting diodes, exhibit a bowing of the band gap as a function of concentration x, and a luminescence spectral width which differs from the expected value of 1.8 kT. Through first-principles calculations, based on many-body perturbation theory and density-functional theory with a meta-GGA exchange–correlation functional, we explore jointly these effects, in an exhaustive set of Ga(1−x)InxN supercells with 16 atoms. We disentangle the bowing due to the average volume change with the one due local atomic configuration and local relaxation. The first one account for about 40% of the bowing, despite that fact that the change of volume with respect to concentration is nearly linear (Vegard’s law). The computed bowing parameter is 1.39 eV. The experimental broadening between 3 kT and 8 kT, not examined theoretically until now, is well accounted by local atomic configuration changes and lifting of the degeneracy of the top of the valence band.

Size-induced evolution of optical properties in gallium selenide thin layers

Thin layers of gallium selenide (GaSe) have been fabricated on Si:SiO2 substrates by micromechanical exfoliation. Size-induced effects in GaSe thin layers of various thickness have been revealed. The photoluminescence maximum associated with direct free exciton transition shifts to higher energies with reduction of GaSe crystal thickness. When going from the bulk GaSe crystal down to 6 tetralayers, the bandgap value increases from 2 eV (620 nm) to 2.17 eV (571 nm). No photoluminescence signal has been detected for GaSe layers thinner than 6 TL. At the same time, the Raman spectra of thin GaSe flakes demonstrate the features corresponding to Ga2Se3, Ga2O3 and other compounds. The appearance of these lines is attributed to thermal and photo-induced oxidation of GaSe layers. For the thin flakes, a remarkable modification of the photoluminescence spectra shape takes place. Presumably, it is a consequence of the electronic structure evolution, as the top of the valence band has undergone changes and has flattened for 8 TL.

Hybrid triazine-based g-C3N4(0 0 1)/anatase TiO2(0 0 1) heterojunction: Insights into enhanced photocatalytic mechanisms via DFT calculation

Understanding is far from satisfactory on the photocatalytic enhancement mechanism of g-C3N4/TiO2 composite by experimental methods. The objective of this study is to investigate the interface properties of the g-C3N4(001)/ TiO2(001) (remarked as CN/T/(001)) heterojunction by the density functional theory calculations for exploring the enhanced photocatalytic mechanisms. The calculated band structures revealed that the CN/T/(001) heterojunction was an indirect-gap semiconductor. The calculated energy gap (Eg) of the CN/T/(001) was much smaller than that of the TiO2(001) and g-C3N4(001) facet. Besides, the maximum value of valence band (VBM) and minimum value of conduction band (CBM) of CN/T/(001) was extended to a higher energy region than those of two side surfaces, suggesting the CN/T/(001) nanocomposite showed a longer redshift of absorption edge. A polarized field within the interface region was formed by the charge transfer between the TiO2(001) and g-C3N4(001) surface, which was beneficial to the separation of photo-generated carriers. These findings all indicated that the CN/T/(001) heterojunction demonstrated a type-II band alignment structure. The electronic structure analysis of TiO2(001), (101) and (100) facets indicated that the Fermi level of (001) and (101) facets occupied the position of conduction band. However, the Fermi level of (100) facets was still located at the top of the valence band. It is speculated that this is the reason why different crystal faces would construct different types of heterojunctions.

Hopping conduction in FeSi. I. The Hall, Seebeck, and Nernst effects due to hopping conduction in the top and bottom impurity Hubbard bands

FeSi is known as a narrow-gap semiconductor showing peculiar temperature dependence of transport properties, which evoked debate for over 50 years. In this study, it is shown that the peculiar temperature dependence of the electrical conductivity σ, the Hall coefficient RH, the Hall mobility μH, the Seebeck coefficient S, and the Nernst coefficient Q of FeSi can be well explained in a model that includes the conduction and the valence band with parabolic dispersions together with the top and bottom impurity Hubbard bands. In particular, the coincidence of the hump of σ(T), the maximum of S(T), the minimum of μH(T), and the maximum of Q(T) can be attributed to the contribution from hopping conduction in the top impurity Hubbard band.

Effect of polarization on performance of inverted solar cells based on molecular ferroelectric Hexane-1,6-diammonium pentaiodobismuth without electron transport layer

Ferroelectric photovoltaic materials are more stable compared to perovskite materials and are increasingly promising as light absorbing layers for the fabrication of solar cells. In this paper, a narrow bandgap molecular ferroelectric Hexane-1,6-diammonium pentaiodobismuth (HDA-BiI5) is used to fabricate solar cells, and the structure of inverted electron transport-free layer is determined after calculating its conduction band bottom and valence band top. The results show that the short-circuit current density (Jsc) of the device reaches 1.057 mA/cm2 at the third bias scan, which is about 9 times the initial performance of the device. Although the change of open circuit voltage (Voc) is not obvious, while the photoelectric conversion efficiency of the device is improved significantly. The improved photovoltaic performance of the device is due to the combined effect of the depolarization field formed after multiple polarizations and the built-in electric field at the P-N junction.

Unveiling the multilevel structure of midgap states in Sb-doped MoX2 (X=S, Se, Te) monolayers

In this study, we use first-principles calculations to investigate the electronic and structural properties of $\text{Mo}{X}_{2}$ $(X=\text{S}, \mathrm{Se}, \mathrm{Te})$ monolayers doped with substitutional Sb atoms, with a central focus on the Sb(Mo) substitution. In ${\mathrm{MoS}}_{2}$, we observe that this substitution is energetically favored under S-rich conditions, where the ${\mathrm{S}}_{2}$ gaseous phase is likely to be present. This result is compatible with a recent experimental observation in Sb-doped ${\mathrm{MoS}}_{2}$ nanosheets grown by chemical vapor deposition. A similar behavior is found in ${\mathrm{MoSe}}_{2}$, but in ${\mathrm{MoTe}}_{2}$ the Sb(Mo) substitution is less likely to occur due to the possible absence of gaseous Te phases in experimental setups. In all cases, several impurity-induced states are found inside the band gap, with energies that span the entire gap. The Fermi energy is pinned a few tenths of eV above the top of the valence band, suggesting a predominant $p$-type behavior, and gap energies are slightly increased in comparison to the pristine systems. The orbital nature of these states is further investigated with projected and local density of states calculations, which reveal similarities to defect states induced by single Mo vacancies as well as their rehybridization with the $5s$ orbital from Sb. Additionally, we find that the band gap of the doped systems is increased in comparison with the pristine materials, in contrast with a previous calculation in Sb-doped ${\mathrm{MoS}}_{2}$ that predicts a gap reduction with a different assignment of valence band and impurity levels. We discuss the similarities, discrepancies, and the limitations of both calculations. We also speculate possible reasons for the experimentally observed redshifts of the $A$ and $B$ excitons in the presence of the Sb dopants in ${\mathrm{MoS}}_{2}$. We hope that these results spark future investigations on other aspects of the problem, particularly those concerning the effects of disorder and electron-hole interaction, and continue to reveal the potential of doped transition-metal dichalcogenides for applications in optoelectronic devices.