Absorption Coefficient Spectra Research Articles

Synthesis, microstructural and optical characterizations of sol-gel grown gadolinium doped cerium oxide ceramics.

In this study, through the utilization of the sol-gel combustion tactic, gadolinium (Gd)-doped cerium oxide (CeO2), Ce1-xGdxO2 (x = 0.00, 0.10, 0.20 and 0.30 (GDC)) ceramics were attained. The synthesized GDC ceramics were investigated using X-ray diffraction (XRD) to scrutinize their crystal structures and phase clarities. The obtained GDC ceramics have a single-phase cubic structure and belong to the crystallographic space group fm3̄m (225). The measurement of the diffraction angle of each reflection and the subsequent smearing of the renowned Bragg's relation provided coarse d-interplanar spacings. The stacking fault (SF) values of pure and Gd-doped CeO2 ceramics were assessed. To muse the degree of preferred orientation (σ) of crystallites along a crystal plane (h k l), the texture coefficient (Ci) of each XRD peak of GDC ceramics is gauged. By determining the interplanar distance (dh k l), the Bravais theory sheds light on the material's development. By exploiting Miller indices for the prime (1 1 1) plane, the lattice constants of GDC ceramics and cell volumes were obtained. Multiple techniques were employed to ascertain the microstructural parameters of GDC ceramics. A pyrometer substantiated the density of GDC ceramics. The room temperature (RT) Fourier transform infrared (FTIR) spectra of both un-doped and Gd-doped CeO2 were obtained. The UV-vis-NIR spectrometer recorded the GDC ceramics' reflectance (R) spectra at RT. For both undoped and Gd-doped CeO2, the absorption coefficient (α) spectra showed two distinct peaks. The R-dependent refractive index (η) and the α-dependent extinction coefficient (k) were determined for all GDC samples. The optical band gap (Eg) was obtained by integrating the Tauc and Kubelka-Munk approaches for GDC ceramics. For each GDC sample, the imaginary (εi) and real (εr) dielectric constants, as well as the dissipation factor (tan δ), were determined local to the characteristic wavelength (λc). Calculations were made for the Urbach energy (EU) and Urbach absorption coefficient (α0) for GDC ceramics. The minimum and maximum values of optical (σo) and electrical (σe) conductivity for GDC ceramics were determined. The volume (VELF) and surface (SELF) energy loss functions, which depend on the constants εi and εr, were used to measure electrons' energy loss rates as they travel across the surface. Raman spectroscopy revealed various vibrational modes in GDC ceramics. Finally, the implications are discussed herein.

Optical Gain Spectrum and Confinement Factor of a Monolayer Semiconductor in an Ultrahigh-Quality Cavity.

Two-dimensional (2D) semiconductors have attracted great attention as a novel class of gain materials for low-threshold, on-chip coherent light sources. Despite several experimental reports on lasing, the underlying gain mechanism of 2D materials remains elusive due to a lack of key information, including modal gain and the confinement factor. Here, we demonstrate a novel approach to directly determine the absorption coefficient of monolayer WS2 by characterizing the whispering gallery modes in a van der Waals microdisk cavity. By exploiting the cavity's high intrinsic quality factor of 2.5 × 104, the absorption coefficient spectrum and confinement factor are experimentally resolved with unprecedented accuracy. The excitonic gain reduces the WS2 absorption coefficient by 2 × 104 cm-1 at room temperature, and the experimental confinement factor is found to agree with the theoretical prediction. These results are essential for unveiling the gain mechanism in emergent, low-threshold 2D-semiconductor-based laser devices.

Retrieval of leaf-level fluorescence quantum efficiency and NPQ-related xanthophyll absorption through spectral unmixing strategies for future VIS-NIR imaging spectroscopy

Current and future vegetation imaging spectroscopy satellites will bring a new data stream of information, of high scientific value to refine existing remote sensing products, and develop new ones. The sensors on board ESA's Fluorescence Explorer (FLEX) will cover the entire 500–780 nm range, designed to track the photosynthetic energy partitioning based on the key pigment players in the light reactions. To quantify the actual photosynthetic efficiency unambiguously, the dynamic pigment absorption behavior is crucial to complement the fluorescence information. An important role is given by the xanthophylls, regulating the non-photosynthetic quenching (NPQ) behavior which affects the 500–600 nm range. Therefore, this work focused on the development of a non-negative least squares (NNLS) spectral unmixing algorithm for reflectance (500–780 nm) retrieving the effective absorbance of individual pigments, i.e., Chlorophyll (Chl) a and b, beta-Carotene and xanthophylls. The NNLS fitting was applied to fit the total effective absorbance at leaf level, linearly composed of pigment and background absorption coefficient spectra. The model succeeded to obtain spectral fitting errors generally below 20% across the 500–780 nm range. Further, we focused on the further use of the effective absorbance by Chlorophyll a to calculate the absorbed photosynthetically active radiation or APAR Chl a. This product was combined with the total emitted fluorescence flux (670–780 nm), expressed in photon flux units, to obtain the fluorescence quantum efficiency (FQE), capturing the stress-related fluorescence quenching in the light reactions. Finally, we applied the leaf-based algorithm to foreseen FLEX image products simulated by the FLEX End-to-End Scene Generator. We were able to retrieve APAR Chl a with a RMSE of 85.5 μmol m−2 s−1 (NNLS with additional upper fitting constraints) and 158.2 μmol m−2 s−1 (regular NNLS), and FQE retrievals could be obtained with an R2 of 0.93 and 0.90, respectively. While the subtle xanthophyll absorption could be meaningfully fitted at the leaf scale, further improvements to the algorithms and an understanding of the physiological mechanisms are needed to deal with the complexity at larger scales. Given several challenges to be overcome, the proposed bottom-up strategy using specific pigment absorbance unmixing for (imaging) spectroscopy demonstrates the ongoing developments to complement the fluorescence product, with the aim to provide an unambiguous estimate on the actual carbon sequestration of vegetation.

Acoustic Performance of a Metamaterial Coating with Uncertainty in Design Parameters

The effect of uncertainty in design parameters on the acoustic performance of a viscoelastic metamaterial coating is investigated. The coating is composed of a layer of hard inclusions embedded in a soft host medium. The layer of inclusions in the soft medium is modelled as a homogenised layer using effective medium approximation theory. Stochastic models based on the polynomial chaos expansion (PCE) method and Monte Carlo (MC) simulations are developed. The effect of uncertainty in geometric and material parameters are quantified by examining the mean and envelopes of the absorption coefficient. Uncertainty in geometric and material parameters produce similar levels of variation in the absorption coefficient of the coating, particularly around the peaks of the absorption coefficient spectrum.

Optical properties of melon tissues and Monte Carlo simulation of light propagation through melon fruit

Visible/near-infrared (Vis/NIR) spectroscopy has been authenticated for quality evaluation of melon fruit. However, since melon is a multi-layered fruit with large size, the optical properties (OPs) of different tissue layers can influence the performance of the quality evaluation. Therefore, the OPs of different tissue layers (exocarp, green mesocarp and pulp) among different fruit positions (stem, equator and calyx) of 36 ‘Huanghemi’ melons were measured using single integrating sphere measurements and the light propagation through melon fruit was investigated by the Monte Carlo (MC) simulation based on the OPs. Moreover, the relationship of the OPs with microstructure and internal quality properties (soluble solids content (SSC) and moisture content) was explored. In the absorption coefficient (μa) spectra, five obvious absorption peaks for carotenoids (481 nm), chlorophyll (675 nm) and water (984, 1195 and 1423 nm) were observed. The exocarp had the highest μa values at 481 nm owing to its orange-yellow peel and the lowest μa values at 1423 nm, while the μa values of green mesocarp and pulp had no significant differences at all absorption peaks. The differences in reduced scattering coefficient (μs') spectra were obvious with a decreasing trend from the outermost (exocarp) to the innermost (pulp) layer and the stem to the calyx position in pulp layer, which mainly related to the different tissue structure. The MC simulation results indicated that the energy along the wavelength was mainly absorbed by the exocarp and green mesocarp, with a ‘diagnostic window’ appearing in 700–850 nm. As the source-detector distance increased, the mean optical pathlength and attenuation of detected photons in each tissue layer increased, while the contribution fraction to the detected diffuse reflectance signals by the exocarp, green mesocarp and pulp respectively decreased, increased and increased. To acquire more information about the pulp and ensure a good signal-to-noise ratio of the spectral signal, a source-detector distance of 7 mm with a suitable light source power would be a good choice. Furthermore, the best prediction models with good performance for SSC and moisture content were built based on the μa spectra, with the correlation coefficient of prediction (Rp) of 0.78–0.80, 0.76–0.88 and the root mean square error of prediction (RMSEP) of 0.83–0.92%, 0.70–0.93%. This study was the first attempt to measure the OPs of melon tissues and investigate the light propagation through melon fruit, which would provide a reference to develop nondestructive testing techniques or instruments for melon fruit based on Vis/NIR spectroscopy.

Fabrication, electrical performance analysis and photovoltaic characterization of β-H2Pc/p-Si heterojunction for solar cell device applications

The aim of this study was to explore the potential of nanocrystalline β-metal-free phthalocyanine (β-H2Pc) in optoelectronics, particularly for the creation of a β-H2Pc/p-Si heterojunction. With a focus on photovoltaic performance, the present work aimed to assess its thermal stability, crystalline structure, optical characteristics, electrical behavior, and applicability in optoelectronic applications. We successfully fabricated a β-H2Pc/p-Si heterojunction at room temperature using a conventional high-vacuum thermal evaporation method, offering a practical approach for integrating these materials into electronic devices. Thermal gravimetric Assessment (TGA) confirmed β-H2Pc’s remarkable thermal stability up to 470 °C, which holds significant promise for high-temperature applications. Transmission Electron Microscopy (TEM) revealed the nanocrystalline nature of the deposited β-H2Pc, which is crucial for the structural integrity of advanced electronic devices. The absorption coefficient spectrum exhibited distinct absorption bands attributed to π–π* excitations, with electronic transitions identified and characterized by a 1.51 eV onset band gap and a 2.74 eV fundamental optical energy gap, highlighting its potential in optoelectronic applications. The current–voltage characteristics of the β-H2Pc/p-Si heterojunction displayed a diode-like behavior at various temperatures, with excellent rectifying properties. Photovoltaic behavior under illumination showed a power conversion efficiency of 1.1%, emphasizing its promise for renewable energy applications and future optoelectronic devices.

Inverse design of acoustic coatings using Bayesian inference

A Bayesian approach for the inverse design of acoustic coatings for underwater noise control is presented. The coating model comprises a periodic arrangement of voids embedded in a soft viscoelastic material. The viscoelastic material is attached to a steel backing with water on its incidence side and air on its transmission side. The acoustic performance of the coating is strongly dependent on the geometric properties of the voided inclusions as well as the number of layers of voids in the direction of sound propagation. The geometric optimization process using Bayesian inference proceeds inversely from a target absorption coefficient spectrum to the required number of voided layers, the geometric design parameters in each layer, and the distance between each layer. The Bayesian design process demonstrates that broadband sound absorption can be achieved using a multilayered coating with a gradient change in both void diameter and distance between each layer. Optimized designs using the Bayesian approach are validated against results obtained numerically as well as experimental results from the literature.

Combined density functional theory and boundary element methods study on optical and electronic properties of interfacial Au/TiO2 defects

This study investigates the optical and electrical properties of Au/TiO2 nanoparticles with different sizes and defects by combining micro- and macro-scale simulations through density functional theory (DFT) and boundary element method (BEM), respectively. The O-vacancy in the sample enhances the bonding and the electron transfer at the Au/TiO2 perimeter zone, as indicated by the binding energy and charge density difference in DFT calculations, respectively. BEM simulation indicates a stronger electromagnetic field in the Au/TiO2 interface of the sample with O-vacancy. DFT calculations demonstrate that the optical absorption of Au/TiO2 in the ultraviolet range is well described by the absorption coefficient spectra, whereas the BEM results well describe the range of the surface plasmon resonance absorption of Au/TiO2 in the wavelength range of 480–550 nm through the absorption cross-section. This study demonstrates the combined role of DFT and BEM in studying the electrical and optical properties of the nanocrystal system.

Research on Non-destructive Testing Method for Aging of Sheds of Composite Insulators

As an important part of external insulation of transmission and distribution lines and substation equipment, silicone rubber insulators are generally used because of their strong anti-pollution flashover ability, excellent hydrophobicity, and lightweight. It is one of the effective means to obtain the aging degree of sheds quickly and accurately to prevent operation accidents. From the micro and macro perspectives, firstly, this paper uses the traditional scanning electron microscopy and dielectric loss factor test to classify the aging degree of 11 high-voltage side sheds samples of silicone rubber insulators running on-site for 0~11 years. According to the different experimental principles, the aging degree of each experimental method is divided into four grades. Then, the detection method based on terahertz time-domain spectroscopy is proposed to realize a nondestructive evaluation of the aging grades of sheds of silicone rubber insulators. Finally, through comparison, it can be found that the THz absorption coefficient spectra can find the characteristic quantity of classification of aging levels of silicone rubber materials: The aging levels of the silicone rubber samples increase, and the absorption peak at 1.32 THz in the absorption spectra show a downward trend. According to the characteristic quantity, 11 samples can also be divided into four aging grades, and the results are consistent with the previous experiments.

Electronic and optical properties of eccentric two dimensional quantum rings subjected to transverse tilted magnetic field

ABSTRACT Within the effective mass approximation framework, the electronic and optical properties of GaAs-based two-dimensional eccentric quantum rings subjected to a transverse magnetic field with an inclination θ-angle to the x-axis are investigated using a two-dimensional diagonalisation method. The results show that the electron energy spectra in concentric quantum rings reveal transparency to the action of magnetic field orientation, contrary to their optical properties, which turn out to be anisotropic with this later. In addition, the eccentricity preserves the absorption coefficient spectra for y-polarisation for all orientations of the magnetic field qualitatively, while those of x-polarisation are significantly modified by eccentricity and magnetic field. Specific peak transitions occurring at specific magnetic field values and θ-angle can be used as a signature of magnetic field orientation and eccentricity.

Temperature-Dependent Optical Properties of Oxidized Graphenes.

In this study, we investigate how changing important synthesis-related parameters can affect and control the optical characteristics of graphene oxide (GO) and reduced graphene oxide (rGO). These parameters include drying time and reduction time at two different temperatures. We obtain an understanding of their impact on optical transitions, optical bandgap, absorption coefficient, and absorbance spectrum width by analyzing these factors. Accordingly, GO has an optical bandgap of about 4 eV, which is decreased by the reduction process to 1.9 eV. Both GO and rGO display greater absorption in the visible spectrum, which improves photon capture and boosts efficiency in energy conversion applications. Additionally, our results show that GO and rGO have higher absorption coefficients than those previously reported for dispersions of exfoliated graphene. Defects in GO and rGO, as well as the presence of functional oxygen groups, are the main contributors to this increased absorption. Several measurements are carried out, including spectroscopic and morphological studies, to further support our findings.

A Method of Evaluating NV centers Concentration by UV–Vis Transmittance Spectra

The ultraviolet-visible (UV-Vis) spectrum was not generally considered an available method for measuring the concentration of negatively charged nitrogen-vacancy (NV-, NV center). In this study, we propose the idea of evaluating the concentration of NV center by the slope of the UV-Vis spectrum. To establish this new method we synthesized diamonds with different NV center concentrations by the chemical vapor deposition (CVD) method. We then measured the zero-phonon line (ZPL) intensity of PL spectra at 637 nm and estimated the concentration of the NV centers as a baseline for comparison to our new UV-Vis method. The UV-Vis transmission spectra were then measured and transformed to relative absorption coefficient spectra. Slopes of the transformed UV-Vis spectra between 400 nm and 800 nm were calculated and compared with the ZPL intensities. The results show a strong positive correlation between the slopes of the absorption spectra and the ZPL intensities of PL spectra at 637 nm. Therefore, this paper demonstrates the feasibility of estimating the concentration of the NV centers from measuring the transmission UV-Vis spectrum.

An operational model for separating the absorption of optically active constituents from SeaWiFS measurements

ABSTRACT To analytically or semi-analytically convert satellite-measured remote sensing reflectance (R rs) to widely used biogeochemical variables from the global oceans, it is common to first determine the total absorption coefficient from satellite R rs data and then separate the total absorption coefficient into the absorption coefficients of phytoplankton (a ph ) and non-phytoplankton (a dg ) pigments. While still considering the spectral characteristics of a ph and a dg , we developed an operational model to improve the accuracy of estimating a ph and a dg products from satellite R rs data. Our results show that our model effectively separates a ph and a dg from the total absorption coefficient spectrum, which decreases the uncertainty by 6.81% to 17.52% compared to a widely used quasi-analytical algorithm. Moreover, after applying the new model to SeaWiFS satellite images, we present the spatial and temporal variations of a ph (443) and a dg (443) for the global oceans from 1997 to 2010, further confirming that coastal zones exhibited higher a ph (443) and a dg (443) than the open oceans during that time. In addition, a ph (443) and a dg (443) declined in the tropical Indian Ocean Gyre over those 13 years. Our results improve our knowledge of the spatiotemporal variations of optical properties of the global oceans, and also demonstrate the potential of our model in separating the total absorption.

Investigating structural, electronic and optical properties of Sc2CF2@Fe MXene: A first principle study

In this work, the structural, electronic and optical properties of novel 2D Sc2CF2 MXene alloyed with Fe are studied by first-principles calculations. The computational method is based on the density functional theory (DFT) and generalized gradient approximation (GGA) considering non-spin–orbit and spin–orbit coupling (SOC). By analyzing the behavior of spin-polarized band structure and density of states (DOS), metallic behavior for all alloy compositions has been predicted. In addition, for all alloy compositions except for c=0.5, the ferromagnetic property has been discovered. Moreover, the optical properties like real and imaginary parts of dielectric and energy loss functions, optical conductivity, absorption coefficient, and reflectivity spectrum have been studied. The results of the absorption coefficient and reflectivity spectrum as a function of photon energy predict that the compounds can be sound absorbers at both visible-light and ultraviolet wavelength regions.

Exploring the structural properties and the optoelectronic features of RbPbX3 (X [formula omitted] Cl, F) perovskite crystals for solar cells solicitations: Showcasing the DFT predictions.

A comprehensive study of the structural, optical, and electronic properties of RbPbX3 (where X is Cl or F) perovskite crystals is reported herein. The calculations of the different physical properties of these two distinguishable RbPbCl3 and RbPbF3 perovskite crystals have been carried within the framework of the Density Functional Theory (DFT) approach for the cubic temperature-dependent phase. The study is motivated by the exploration of innovative perovskites materials for solar cells application due to the marvelous augmentation in power conversion efficiency (PCE) obtained by perovskite crystals (≈ 25% up to date). The investigation were undertaken for determining the perceivable role of the X element in their band gap energy features as well as the band structure proprieties. The simulations were commenced by determining the optimal lattice constants and the lowest total energy of both perovskite crystals. The exploration of the electronic properties of RbPbCl3 and RbPbF3 perovskite crystals have been studied by estimating their variation upon employing spin–orbit-coupling (SOC) and without taking into consideration the SOC interaction by means of LDA-pz and GGA-PBE exchange potentials within the framework of projector augmented wave method (PAW) and the Perdew–Burke–Ernzerh of LDA and (PBE) variant of the generalized gradient approximation (GGA). The integrated suite quantum-ESPRESSO is used for materials modeling, structure calculations, and electronic properties of the studied RbPbCl3 and RbPbF3 perovskite crystals. The thermo_pw driver is employed for the determination of the elastic properties whereas the optical properties were elucidated by aid of Yambo code through solving the many-body perturbation theory (MBPT) approach as introduced in the open-source code. The optical band gap of cubic RbPbCl3 and RbPbCF3 within LDA and PBE, were observed at (2.18, 2.2) eV and (2.4, 2.5) eV respectively. Compared and contrasted with those revealed by the electronic band gap energy of the systems, these obtained values are very consistent with the experimental. The two maximum peaks for the absorption coefficients are found to be within the visible range rending the two perovskite crystals in promising candidate for solar cell applications. Despite some quantitative differences, the material’s enhancement potential is well demonstrated by the absorption coefficient spectrum, refractive index, and conductivity. The study holds promise for solar cell applications and may pave the way for consideration of the RbPbCl3 and RbPbF3 as well as their doped analogs for perovskites-based solar cells as the next generation in the photovoltaic industry.

Numerical Simulation of a Light Field Structure in an Integrating Sphere via the Monte Carlo Method

The integrated cavity absorption meter is designed to measure the seawater absorption coefficient spectra which are necessary for studying ocean productivity and heat balance. The performed numerical simulations of a light field structure made it possible to improve the measurement technique. Its results showed that the use of the Lambertian model allows to reduce the calculation time by two orders of magnitude with an acceptable loss of accuracy for these calculations. It is shown that in the case of an integrating sphere made of fluorilon, the use of different volume scattering functions does not affect the calculation result, which is not true in the case of using a sphere with a mirror coating. The effect of an air layer between quartz and fluorilon is considered, and the applicability of the diffusion approximation is verified. Examples of field measurements of the seawater absorption coefficient and its components performed in different water areas of the World Ocean in 2020–2022 are presented.

Extracting Optical Parameters of Cu–Mn–Fe Spinel Oxide Nanoparticles for Optimizing Air-Stable, High-Efficiency Solar Selective Coatings

High-temperature Cu–Mn–Fe spinel-oxide nanoparticle solar selective absorber coatings are investigated experimentally and theoretically. A general realistic approach to evaluate absorption coefficient spectra from the optical measurements of the nanoparticle-pigmented coatings is developed by solving the inverse problem of the four-flux-radiative transfer model. The derived absorption properties are utilized to elucidate the direct and indirect bandgap transitions in the visible spectral regime as well as the sub-bandgap absorption in the infrared range. Furthermore, the optical properties of NP materials can be directly applied to optimize the solar selective coating design and analyze thermal degradation mechanisms. The analysis reveals that the Cu–Mn–Fe spinel oxides are semiconductors with an indirect bandgap ranging from 1.7 to 2.1 eV, while iron-free CuMn2O4 is a direct bandgap material with Eg = 1.84 eV. With the same coating thickness and nanoparticle load, the solar absorptance ranks in the order of Mn2O3 < MnFe2O4 < CuFe2O4 < CuFeMnO4 < CuMn2O4. The optimized spray-coated iron-free CuMn2O4 NP-pigmented coating demonstrates a high solar absorptance of 97%, a low emittance of 55%, a high optical-to-thermal energy conversion efficiency of ∼93.5% under 1000× solar concentration at 750 °C, and long-term endurance upon thermal cycling between 750 °C and room temperature in air. The optical parameter analysis approach can be easily extended to other material systems to facilitate the search and optimization of high-temperature nanoparticle-pigmented solar selective coatings.

Terahertz Spectroscopy Characterization and Prediction of the Aging Degree of Polyethylene Pipes Based on PLS.

Polyethylene (PE) is widely used in pipeline transportation owing to its excellent corrosion resistance, good stability, and ease of processing. As organic polymer materials, PE pipes inevitably undergo different degrees of aging during long-term use. In this study, terahertz time-domain spectroscopy was used to study the spectral characteristics of PE pipes with different degrees of photothermal aging, and the variation in the absorption coefficient with aging time was obtained. The absorption coefficient spectrum was extracted using uninformative variable elimination (UVE), successive projections algorithm (SPA), competitive adaptive reweighted sampling (CARS), and random frog RF spectral screening algorithms, and the spectral slope characteristics of the aging-sensitive band were selected as the evaluation indices of the degree of PE aging. Based on this, a partial least squares aging characterization model was established to predict white PE80, white PE100 and black PE100 pipes with different aging degrees. The results showed that the prediction accuracy of the absorption coefficient spectral slope feature prediction model for the aging degree of different types of pipes was greater than 93.16% and the verification set error was within 13.5 h.

Exploring the candidacy of Mo[formula omitted] A[formula omitted] X2 (A = [Cr, Ta], X = S) for photodetection solicitations: Showcasing the DFT predictions of the structural, elastic, and optoelectronic properties

Previously, most of the theoretical/computational density functional theory (DFT) simulations of transition metal dichalcogenides (TMDs) were used to gain insight into their non-doped structural, elastic, and optoelectronic properties. Although it was shown that most of the TMDs proprieties are relevant giving thereby rise to much more attention due to their promising features with vast potential in many technological applications, it was not clear concerning the stability of these interesting and timely materials. In general, for TMDs the substitutional doping method, which consists of carrier doping by substituting chalcogen or metal sites with impurity atoms, is key for tailoring their physical properties and enabling outstanding stability. In this study, a particular focus will be dedicated to elucidating the stability and the physical properties of Cr and Ta-doped Molybdenum-based TMDs. Since the stability of TMDs depend on the formation energy and occurs on very long timescales, all-DTF and simulations of the physical properties of TMDs are prohibitively costly. However, the inclusion of Cr and Ta in the monolayer MoS2 matrix may pave the way for obtaining excellent stability of TMDs materials and reasonably reduce the computational cost. In this investigation, an illustration of the effect of the Cr and Ta impurities on the overall performance of the monolayer MoS2 matrix will be elucidated. Interestingly, an investigation of Mo(1−x)A(x)X2(A = [Cr, Ta], X = [S]) will be performed starting from the elucidation of the structural properties. It is found that the doped materials are semiconductors within the infrared region, with particular values of the energy gaps. The optical properties findings reveal that Ta–Cr-doped materials are more transparent than those counterparts of Cr and Ta-doped materials. The absorption coefficient spectra, refractive index, reflectivity, and conductivity all reveal good enhancement capability of the doped materials. The computational approach used herein is expected to open the way towards a comprehensive understanding of an efficient application of TMDs doped materials in many ranges of optical applications such as those involved in photodetection technology.

Comparative performance analysis of Cs2TiX6 (X = Br-, Cl-, I-) lead-free perovskite solar cells incorporating single, double and triple layer halides by SCAPS −1D

Halide perovskites have risen in popularity as appealing light absorber materials, owing primarily to their wide range of applications in solar cells, lasers, photodetectors. However, lead-containing perovskites have the potential to cause substantial environmental damage. As a result, there is a significant need to produce environmentally acceptable lead-free perovskites. In this work, we studied the single, double and triple halides perovskite by numerical simulator SCAPS-1D for maximum performance. We have optimized the absorber layer thickness, NA/ND/Nt and interface defect density, back contact electrodes, and temperature effects in a single absorber layer structure. Further, we have optimized the double and triple-layer absorbers for perovskite solar cell structures. The maximum efficiency achieved in the double halide perovskite solar cell is VOC = 1.54 V, JSC = 24.04 mA/cm2, FF = 82.72%, and PCE = 30.06%. Such performance is due to the absorption coefficient spectrum with a wide range of energy band gaps. This has proved its suitability for photovoltaic devices. Overall, our findings reveal that Cs2TiX6 (X = Br, Cl, I) Pb-free perovskites have promising and potential features for device performance.