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Strain engineering is a powerful technique for controlling the performance of semiconductor ceramic systems. In this article, the effect of strain engineering, specifically biaxial compressive and tensile strains, on the bonding characteristics, structure, electronic, and optical properties of nonplanar phosphorene‐like (NPP) ZnS ceramic nanolayers was investigated using density functional theory. It was observed that this ceramic exhibits greater stability under significant tensile strains. The structural stability of NPP‐ZnS ceramic, both with and without biaxial strain, was confirmed by its negative formation energy. Biaxial strain strongly influences the electronic band structure of NPP‐ZnS ceramic nanolayers, leading to a transformation from a direct band gap to an indirect gap under tensile strain. Additionally, the bandgap decreases under compressive strain, while it slightly increases under tensile strain. Various optical properties, including refractive index, extinction coefficient, absorption, reflectivity, optical conductivity, and optical susceptibility, were calculated. Biaxial compressive and tensile strains alter the optical properties, shifting them to higher or lower frequencies. NPP‐ZnS ceramic nanolayers exhibit high optical absorption in the UV range, which can be further enhanced by biaxial strain. Furthermore, under increasing compressive strain, the absorption edge moves toward higher energies. This improvement in optical absorption expands the potential applications of NPP‐ZnS ceramic nanolayers in optoelectronic devices. [ABSTRACT FROM AUTHOR]

The absorption spectra of various sizes of nanoparticles of copper (Cu), silver (Ag), and gold (Au) are theoretically investigated. The density functional theory (DFT), time‐dependent DFT (TDDFT), and real‐time TDDFT are used to demonstrate how size and shape affect their optical properties and how these are evolved as the number of atoms increases. For this reason, the focus was turned on almost spherical nanoparticles cut out from the corresponding crystal structure (called 0D), elongated ones (1D), and flattened ones (2D). The nature of the observed absorption peaks is further analyzed with the help of transition contribution maps and induced density plots which help us identify the emergence of probable plasmonic resonances as the size of the nanoparticles increases. [ABSTRACT FROM AUTHOR]

We present a comprehensive investigation of the electronic properties of fluorinated monolayer violet phosphorus using first‐principles calculations. Our results reveal a strong dependence of the electronic properties on the different fluorine coverages of fluorination. As the fluorine coverage increases, monolayer violet phosphorus undergoes a significant transition from a wide direct bandgap semiconductor to a narrow indirect bandgap semiconductor. Moreover, both semi‐fluorinated and fully fluorinated monolayer violet phosphorus exhibit advantageous semiconducting characteristics, with a tunable bandgap of 0.50 ~ 1.04 eV under biaxial strain ranging from −6% to 6%. Notably, the fully fluorinated monolayer violet phosphorus demonstrates a higher coefficient of light absorption within the visible range. Therefore, our findings highlight the tunability of monolayer violet phosphorus properties through the absorption of various fluorine coverages, providing valuable insights for the design and development of novel semiconductor devices based on this material. [ABSTRACT FROM AUTHOR]

Crystals of the family of tetragonal, non‐centrosymmetric melilites have attracted interest as nonlinear optical, piezoelectric, and ferroelectric materials. This work presents an ab initio study of the optical properties of europium melilite, Eu2MgSi2O7. The study includes the calculation of refractive and absorption spectra, with respect to the density of states of the system. The obtained results demonstrate the correlation between the electronic structure of europium melilite and its optical characteristics. [ABSTRACT FROM AUTHOR]

The structural stability, elastic, optoelectronic, and thermoelectric characteristics of anti‐perovskites Na3XO (X = Cu, Ag) have been studied using density functional theory (DFT). The computed formation energy suggests these materials' potential synthesis and thermal stability. The structural and elastic properties of Na3CuO and Na3AgO anti‐perovskite compounds were analyzed using the Perdew–Burke–Ernzerhof (GGA‐PBE) generalized gradient potential approximation. The electronic and thermoelectric properties are calculated using the TB‐mBJ approximation. The materials are identified as direct narrow band gap semiconductors with band gaps of 0.65 and 0.43 eV. The analysis of two‐dimensional charge density contours indicates that Na3CuO and Na3AgO have a mixed bonding character, as validated by the investigation of electron charge density. We analyzed the optical properties of Na3CuO and Na3AgO, including dielectric function, refractive index, absorbance, optical reflectivity, and energy loss, using photon energy up to 6 eV. The investigated thermoelectric characteristics demonstrate figure of merit (ZT) values of 0.58 and 0.56 at room temperature. Consequently, the analyzed anti‐perovskites might address waste heat management requirements and sustainable energy solutions. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive analysis of the orthorhombic CsCuO, focusing on its structural, electronic, mechanical, and optical properties, which uses the first‐principles plane wave pseudopotential technique and local density approximation methods based on density functional theory. The derived structural parameters closely match the previously reported experimental data. The calculated results show that CsCuO is mechanically stable and exhibits a certain toughness. Research on electronic properties shows that CsCuO is a direct‐bandgap semiconductor. Charge density and population analysis show that covalent bonds are formed between O and Cu. The optical property results show that CsCuO has good passability to incident light, indicating that CsCuO is an excellent transparent material. In the visible and infrared light regions, CsCuO has a low absorption coefficient, mainly manifested as ultraviolet absorption. Reflection is mainly distributed in the high‐energy region and does not exceed 25% in the visible light region. It can be used in fields that require less light reflection and the manufacture of medical ultraviolet disinfection equipment. [ABSTRACT FROM AUTHOR]

Thermochromic materials, known for their unique ability to change optical properties with temperature, have broad applications, including in thermochromic light‐emitting diodes (LEDs). However, the scarcity of efficient and stable thermochromic phosphors limits their development. In this study, the development of a novel thermochromic phosphor based on zero‐dimensional (0D) inorganic metal halides is reported. The 0D Cs2ZnBr4:Ag+ phosphors show thermally enhanced self‐trapped exciton (STE) emission across a wide temperature range from 120 to 300 K with the emitted wavelength changing correspondingly. Temperature‐dependent photoluminescence (PL), time‐resolved PL, and density functional theory calculations confirm that the thermally enhanced STE emission originates from the passivated defect/traps in Cs2ZnBr4 and the thermally assisted energy transfer from the host to STEs formed by [AgBr4]3– tetrahedron with matrix phonons complementing the energy mismatch. Furthermore, the reversible thermochromic LEDs based on Cs2ZnBr4:Ag+ phosphors are successfully prepared. Overall, these findings provide a future design of high‐efficiency thermally enhanced luminescent materials and pave a new way for developing thermochromic materials for functional LED illumination. [ABSTRACT FROM AUTHOR]

The full potential linearized augmented plane wave (FP‐LAPW) method is used to compute structural, electronic, and optical properties of III‐V semiconductor ternary alloys GaP1‐xSbx (0≤x≤1) using first‐principle calculations within density functional theory. To calculate the ground state parameters of the structure, the energy exchange‐correlation Wu‐cohen generalized gradient approximation is employed in the wiek2k program. The Tran–Blaha‐modified Becke–Johnson (TB‐mBJ) pseudopotential is employed in addition to the Wu‐Cohen generalised gradient approximation to achieve a precise bandgap. After this, WC‐mBJ is used to examine optical properties such as real and imaginary parts of the dielectric constant, and energy loss. This study illustrates the nonlinear dependency on the various Sb compositions by examining the composition impacts on the bandgap, bulk modulus, and lattice constant. Using WC‐mBJ, the estimated band structures for alloys GaP0.75Sb0.25, GaP0.50Sb0.50, and GaP0.25Sb0.75 show direct energy bandgaps of 2.008 eV (617 nm), 1.482 eV (836 nm), and 1.055 eV (1174 nm), respectively. As a result, this material system has enormous potential for use in applications spanning the visible to infrared spectrum. [ABSTRACT FROM AUTHOR]

A novel allotrope structure of carbon named twin irida graphene composed of 3‐16‐8 carbon rings is proposed. Its structural, mechanical, electronic, and optical characteristics are explored by density functional theory. It is shown that twin irida graphene has an energetically favorable structure. Its dynamical and thermal stabilities at room temperature are also examined and confirmed. The in‐plane stiffness of twin irida graphene is less than graphene. It is a metal and maintains this property even against the external strain and applied electric field. This sheet exhibits an anisotropy response to the incident photon with different polarizations. The potential of sheet for use in energy storage and absorption systems is indicated by its high dielectric constant and optical absorption. The reflection constants as well as the transmission constants of twin irida graphene indicate its transparency, mostly in the high‐energy region. Thus, twin irida graphene is a suitable material for use in optoelectronic applications due to its structural and physical characteristics. [ABSTRACT FROM AUTHOR]

In this study, the pressure‐induced structural, electronic, and optical properties of lead‐free inorganic Ge‐based perovskite materials NaGeX3 (X = F, Cl, Br, and I) through density functional theory (DFT) simulations conducted are explored with CASTEP. This research is driven by identifying perovskite materials with a tunable bandgap that are both efficient and non‐toxic for solar cell applications. The materials under consideration are found to be mechanically and thermodynamically stable, as per the Born stability criteria and formation energy calculations. This band structure analysis indicates these compounds exhibit semiconducting behavior with a tunable bandgap. Under ambient conditions, the Ge─X and Na─X bonds display covalent and ionic characteristics, respectively. Substituting halogens from F to I increases lattice parameters and a more covalent nature of the Ge─X bond. Concurrently, the bandgap narrows, transitioning from indirect (F) to direct (Cl, Br, and I). At the same time, the static dielectric constant rises, and both absorption and conductivity are significantly enhanced with a redshift in the optical spectrum. The application of tensile stress (positive pressure) increases both the lattice constant and bandgap, whereas the dielectric constant, absorption, conductivity, and reflectivity decrease. Conversely, compressive stress (negative pressure) induces the opposite effect. Pressure‐induced variations in the bandgap highlight the potential of NaGeX3 materials to significantly impact the next‐generation solar cells' development, offering a pathway to more sustainable and efficient energy solutions. [ABSTRACT FROM AUTHOR]

In this article, the properties of Cs2Pb2O3 have been investigated using the first‐principles method. It covers the relevant structural, stability, electronic properties, conductivity, and optical properties. The phonon spectra and elastic properties analysis show the stability of Cs2Pb2O3, band structure, density of states, charge density diagram, and bond populations are analyzed to show the electronic structure of the system more clearly. The calculated results indicate that considering spin‐orbit coupling (SOC) will reduce the band gap. The charge density diagram and bond populations indicate that the Cs–O bond is mainly ionic and the Pb–O bond is mainly covalent and partially ionic. The analysis of optical properties indicates good transparency, and the calculated hole mobility is 10.88 cm2 V−1 s−1, suggesting that it is a promising p‐type conductive oxide. [ABSTRACT FROM AUTHOR]

Employing functional building units with microscopic second‐order NLO response has been proposed to explore high performance NLO materials. Herein, structural, electronic and optical properties of non‐centrosymmetric molybdenyl carbonate Cs3MoO4(HCO3) with NLO active functional units have been examined based on density functional theory. Theoretical results are consistent with experimentally mentioned data, confirming the reliable method. Detailed geometric structure, electronic attributes, linear optical properties, and nonlinear optical properties of Cs3MoO4(HCO3) are provided. Analysis of structures, compositions of bands and plots of charge density suggest that asymmetric functional building units [MoO4] and [HCO3] exhibit varying degrees of second‐order Jahn‐Teller distortions, and therefore have a significant impact on the electronic structure and optical properties of Cs3MoO4(HCO3). Maximum absolute value of SHG coefficients at 1064 nm is 0.671 pm/V for d15, which is nearly twice as much as that of KDP. Further researches are needed in future to validate and enhance optical anisotropy characteristic of Cs3MoO4(HCO3) for satisfying the phase matching conditions. Analysis results indicate that microscopic origins of SHG response in Cs3MoO4(HCO3) are complicated, such as geometric environment, induced polar asymmetric functional building units, and electronic properties. Continuous research on structure‐property relationship of NLO materials is needed for exploring more competitive NLO materials. [ABSTRACT FROM AUTHOR]

Long‐life room temperature phosphorescent (RTP) materials hold significant potential in the fields of optoelectronic devices, information encryption, and bio‐imaging due to their excellent optical properties. However, achieving multi‐color tunable RTP materials has proven challenging. In this study, molecular engineering strategies are employed to select precursor molecules with varying degrees of conjugation such as phthalic anhydride (PA), naphtho[2,3‐c] furan‐1,3‐dione (23NA), and naphthalic anhydride (NA). By combining these guest molecules with a host boric acid matrix through a one‐step microwave method, carbon dots (CDs)composites (PA@BA, 23NA@BA and NA@BA) exhibiting excellent RTP properties are successfully prepared. As the degree of precursor conjugation increased gradually, the phosphorescence color modulation of the composites demonstrates satisfactory transitions from blue to yellow. Notably, CDs are derived in situ within the boric acid matrix while covalent and hydrogen bonds formed between CDs and borate matrix effectively suppress nonradiative leaps and facilitate composite RTP activation. Furthermore, the boric acid matrix acts as insulation against oxygen diffusion and prevents quenching of triplet excitons by external factors. The rationality behind phosphorescence emission mechanism and wavelength modulation is further conformed by density functional theory (DFT) calculations. Finally, CDs composites are successfully applied for advanced message encryption of text and images. [ABSTRACT FROM AUTHOR]

Chemical modification is a powerful strategy for tuning the electronic properties of 2D semiconductors. Here we report the electrophilic trifluoromethylation of 2D WSe2 and MoS2 under mild conditions using the reagent trifluoromethyl thianthrenium triflate (TTT). Chemical characterization and density functional theory calculations reveal that the trifluoromethyl groups bind covalently to surface chalcogen atoms as well as oxygen substitution sites. Trifluoromethylation induces p‐type doping in the underlying 2D material, enabling the modulation of charge transport and optical emission properties in WSe2. This work introduces a versatile and efficient method for tailoring the optical and electronic properties of 2D transition metal dichalcogenides. [ABSTRACT FROM AUTHOR]

A new noncentrosymmetric strontium borate, P1‐Sr2[B5O8(OH)]2 ⋅ [B(OH)3] ⋅ H2O (1), has been synthesized under the hydrothermal condition. The P1‐Sr2[B5O8(OH)]2 ⋅ [B(OH)3] ⋅ H2O shows a layered B−O network with 9‐ring windows in the ab plane. Sr2+ cations, H3BO3, and H2O molecules are located in the voids of layers and interlayers, respectively. The P1‐Sr2[B5O8(OH)]2 ⋅ [B(OH)3] ⋅ H2O is the first synthetic phase of veatchite, while the other three polymorphs are found in different natural minerals. This strontium borate is a potential deep‐ultraviolet‐transparent nonlinear‐optical (NLO) crystal whose second‐harmonic‐generation (SHG) intensity is 1.7 times that of KH2PO4 (KDP) and is phase‐matchable. The short wavelength cutoff edge of compound 1 is below 190 nm. Density functional theory (DFT) calculations show that the B−O units are responsible for the nonlinear optical property. [ABSTRACT FROM AUTHOR]

The effective calculation of static nonlinear optical properties requires a considerably high accuracy at a reasonable computational cost, to tackle challenging organic and inorganic systems acting as precursors and/or active layers of materials in (nano‐)devices. That trade‐off implies to obtain very accurate electronic energies in the presence of externally applied electric fields to consequently obtain static polarizabilities (αij) and hyper‐polarizabilities (βijk and γijkl). Density functional theory is known to provide an excellent compromise between accuracy and computational cost, which is however largely impeded for these properties without introducing range‐separation techniques. We thus explore here the ability of a modern (double‐hybrid and range‐separated) Range‐Separated eXchange Quadratic Integrand Double‐Hybrid exchange‐correlation functional to compete in accuracy with more costly and/or tuned methods, thanks to its robust and parameter‐free nature. [ABSTRACT FROM AUTHOR]

The work aims to investigate the nonlinear optical (NLO) activity of piperazine‐1,4‐diium acetate (PAA) molecule utilizing computational techniques. The computational calculations are performed using density functional theory (DFT) to explore the vibrational modes, electronic and NLO properties of PAA by comparing them with piperazine and acetic acid molecules. The natural bond orbital analysis is performed to identify hydrogen bonding and charge transfer interaction. A vibrational analysis is carried out and the assignment of fundamental modes is done using the vibrational energy distribution analysis (VEDA) program. Molecular electrostatic potential, frontier molecular orbital, electron localization function, localized orbital locator and Fukui analysis are carried out to identify chemical reactivity and charge transfer interaction. The UV–visible analysis is performed to obtain the electronic absorption spectrum. The hole–electron analysis is performed for the first five excitations to identify the type of excitation. The atoms in molecules, reduced density gradient and independent gradient model are performed to identify the hydrogen bonding, steric and van der Waals interactions. Hirshfeld analysis is performed to explore the intermolecular interactions within the PAA molecule. The NLO calculation is performed to evaluate the NLO parameters. The obtained results show that the PAA molecule is suitable for NLO applications. [ABSTRACT FROM AUTHOR]

This study presents the synthesis and characterization of oxonitridosilicate phosphates Sr3SiP3O2N7, Sr5Si2P4ON12, and Sr16Si9P9O7N33 as the first of their kind. These compounds were synthesized under high‐temperature (1400 °C) and high‐pressure (3 GPa) conditions. A unique structural feature is their common fundamental building unit, a vierer single chain of (Si, P)(O, N)4 tetrahedra. All tetrahedra comprise substitutional disorder which is why we refer to it as the fundamental disorder unit (FDU). We classified four different FDU motifs, revealing systematic bonding patterns. Including literature known Sr5Si2P6N16, three of the four patterns were found in the presented compounds. Common techniques like single‐crystal X‐ray diffraction (SCXRD), elemental analyses, and 31P nuclear magnetic resonance (NMR) spectroscopy were utilized for structural analysis. Additionally, low‐cost crystallographic calculations (LCC) provided insights into the structure of Sr16Si9P9O7N33 where NMR data were unavailable due to the lack of bulk samples. The optical properties of these compounds, when doped with Eu2+, were investigated using photoluminescence excitation (PLE), photoluminescence (PL) measurements, and density functional theory (DFT) calculations. Factors influencing the emission properties, including thermal quenching mechanisms, were discussed. This research reveals the new class of oxonitridosilicate phosphates with unique systematic structural features that offer potential for theoretical studies of luminescence and band gap tuning in insulators. [ABSTRACT FROM AUTHOR]

Two novel metal borates, namely, Ag7B9O16(OH)2 (1) and AgCa2B7O11(OH)4 (2) were obtained under hydrothermal conditions. Ag7B9O16(OH)2 crystallizes into the centrosymmetric space group of C2/c in the monoclinic crystal system and displays a unique three‐dimensional (3D) framework built by 1D double borate chains further connected by Ag cations. AgCa2B7O11(OH)4 also belongs to monoclinic space group C2/c and it features borate chains with B8O8 8‐membered rings along the c axis which are further coordinated via AgO3 into 2D layers. These layers are bridged via CaO8 polyhedron into the final 3D framework. Two compounds were further characterized through thermogravimetric and optical analysis and density functional theory calculation have also been carried out, addressing their electronic structures. [ABSTRACT FROM AUTHOR]

Controlled synthesis of lead‐halide perovskite crystals is challenging yet attractive because of the pivotal role played by the crystal structure and growth conditions in regulating their properties. This study introduces data‐driven strategies for the controlled synthesis of oriented quasi‐spherical CsPbBr3, alongside an investigation into the synthesis mechanism. High‐throughput rapid characterization of absorption spectra and color under ultraviolet illumination was conducted using 23 possible ligands for the synthesis of CsPbBr3 crystals. The links between the absorption spectra slope (difference in the absorbance at 400 nm and 450 nm divided by a wavelength interval of 50 nm) and crystal size were determined through statistical analysis of more than 100 related publications. Big data analysis and machine learning were employed to investigate a total of 688 absorption spectra and 652 color values, revealing correlations between synthesis parameters and properties. Ex situ characterization confirmed successful synthesis of oriented quasi‐spherical CsPbBr3 perovskites using polyvinylpyrrolidone and Acacia. Density functional theory calculations highlighted strong adsorption of Acacia on the (110) facet of CsPbBr3. Optical properties of the oriented quasi‐spherical perovskites prepared with these data‐driven strategies were significantly improved. This study demonstrates that data‐driven controlled synthesis facilitates morphology‐controlled perovskites with excellent optical properties. [ABSTRACT FROM AUTHOR]

2D metal phosphorus trichalcogenides (MgPX3) have attracted tremendous research interests in spintronic, electrocatalytic, and photoelectronic applications due to their unique magnetic and optical properties. Herein, a systematical investigation on the electronic structures and optical properties of 2D MgPX3 (X = S and Se) monolayers is performed by density functional theory. Owing to small cleavage energy, 2D MgPX3 monolayers can be obtained by mechanical exfoliation with an excellent structure stability of 2D MgPX3 monolayers demonstrated by elastic tensor, phonon dispersion, and molecular dynamics, respectively. 2D MgPX3 behaves as a direct bandgap semiconductor with a strong optical absorption in UV range whereas a weak adsorption near the band edge, demonstrated by both single‐ and quasiparticle approximations. Upon analyses on transition dipole moment along with the wave function symmetry, the weak optical absorption is attributed to the parity‐forbidden effect where the wave functions almost show the same parity between top valence band and bottom conduction band. The findings indicate that 2D MgPX3 monolayers hold promise as candidate materials for flexible UV photoelectronics devices and provide a theoretical insight into the optical properties of 2D semiconductors. [ABSTRACT FROM AUTHOR]

Density functional theory based on projector‐augmented wave methodology is employed to conduct an in‐depth investigation into the structural, optical, and electrical properties of pristine PdSe2 and Pt‐doped PdSe2 monolayers. The computational framework uses the Perdew–Burke–Ernzerhof functional within the generalized gradient approximation. Evaluation of the calculated formation energy (Eform) and binding energy (Eb) demonstrates the thermodynamic favorability of Se vacancy on PdSe2 and the formation of a strong PtPdSe2 bond. The intrinsic indirect bandgap of PdSe2 (1.2 eV) undergoes a transition to a direct bandgap (0.71 eV) following Pt doping. In the context of optoelectronic applications, the investigation of optical properties reveals an elevated dielectric constant of 4.6 and 1.9 in the XX and ZZ planes for Pt‐doped PdSe2. Enhanced optical absorption is observed at ≈6.8 and 10.7 eV in the XX and ZZ planes, respectively. A notable redshift in the absorption coefficient and reflectivity constitutes significant findings. These results underscore the potential of tailoring PdSe2 optical and electrical properties, offering promising avenues for applications, particularly in the domain of nanoelectronics and optoelectronics devices. [ABSTRACT FROM AUTHOR]

We utilize density functional theory to explore dicarbonitrile‐polyphenyl networks overlaid on graphene as a method for manipulating the density of Li atoms in a specific assembly pattern. Ab initio molecular dynamics calculations affirm the thermal stability of the introduced systems. We scrutinized the electronic structure and optical properties of the resultant systems, illustrating a systematic modulation of optical characteristics. Our results suggest that the optical excitation frequencies of (Li‐dicarbonitrile‐polyphenyl)/G can be efficiently tuned by systematically adjusting the density of Li atoms on graphene. [ABSTRACT FROM AUTHOR]

The density functional theory (DFT) is applied to systematically investigate the geometrical structure, electronic, mechanical, vibrational, and optical properties of double perovskite Rb2LiTlF6 in its cubic phase. To the best of one's knowledge, many physical properties of this compound are still not well established or not yet investigated; such as phonon properties, mechanical behavior, thermal properties, and so on. In this work, the stability of Rb2LiTlF6 is explored by looking at its thermodynamical behavior through calculation of formation energy, cohesive energy, Goldschmidt tolerance factor, and phonon dispersion. Its mechanical properties are examined based on various characterization descriptors such as the independent elastic coefficients, bulk, shear, and Young's modulus, ratios such as Pugh and Poisson's, Kleinnman parameter, Zener anisotropy factor, Debye temperature, and melting temperature. Sound velocity in this material is predicted from the values of the bulk and shear modulus obtained. Thermal expansion coefficient at finite temperatures are obtained using the approach of quasi‐harmonic approximation. Its electronic property is also investigated using generalized gradient approximation and also hybrid functionals. At a later stage, its optical behavior upon the effect of light excitation is explored using the many body pertubation theory approximation. Having envisioned this material as a wide band gap semiconductor, it can be useful in numerous applications such as designing the top‐cell of tandem photovoltaic configuration, photodetection, and light emitting diodes. It is strongly believed that this work will provide a helpful guidance for future experimental and theoretical investigations of this material. [ABSTRACT FROM AUTHOR]

Halide base perovskite LiCdX3 (X = F, Cl) is tested by CASTEP (Cambridge Serial Total Energy Package) based on density function theory (DFT). The presented discussion is to explore the structural, electronic, and optical properties of LiCdX3 (X = F, Cl). The calculated values of the lattice parameter are found to be 3.8 Å and 5.27 Å of LiCdF3 and LiCdCl3 respectively. The ideal structure of LiCdX3 (X = F, Cl) is cubic and dynamically stable. Electronic properties show that materials are semiconductors. The results from band structure are further evaluated by the total and partial density of states. The partial and total density of states confirms the degree of localization of electrons. In optical properties, the highest absorption coefficient is observed in LiCdCl3. The material is half metallic and has a narrow indirect band gap which may be used in photovoltaic applications. [ABSTRACT FROM AUTHOR]

Germanium diselenide (GeSe2) is a 2D semiconductor with air stability, a wide bandgap, and anisotropic optical properties. The absorption and photoluminescence (PL) of single‐crystalline 2D GeSe2 grown by metal‐organic chemical vapor deposition and their dependence on temperature and polarization are studied. The PL spectra exhibit peaks at 2.5 eV (peak A) and 1.8 eV (peak B); peak A displays a strongly polarized emission along the short axis of the crystal, and peak B displays a weak polarization perpendicular to that of peak A. With increasing temperature, peak B shows anomalous behaviors, i.e., an increasing PL energy and intensity. The excitation energy‐dependent PL, time‐resolved PL, and density functional theory calculations suggest that peak A corresponds to the band‐edge transition, whereas peak B originates from the inter‐band mid‐gap states caused by selenium vacancies passivated by oxygen atoms. The comprehensive study on the PL of single‐crystalline GeSe2 sheds light on the origins of light emission in terms of the band structure of anisotropic GeSe2, making it beneficial for the corresponding optoelectronic applications. [ABSTRACT FROM AUTHOR]

Germanium diselenide (GeSe2) is a 2D semiconductor with air stability, a wide bandgap, and anisotropic optical properties. The absorption and photoluminescence (PL) of single‐crystalline 2D GeSe2 grown by metal‐organic chemical vapor deposition and their dependence on temperature and polarization are studied. The PL spectra exhibit peaks at 2.5 eV (peak A) and 1.8 eV (peak B); peak A displays a strongly polarized emission along the short axis of the crystal, and peak B displays a weak polarization perpendicular to that of peak A. With increasing temperature, peak B shows anomalous behaviors, i.e., an increasing PL energy and intensity. The excitation energy‐dependent PL, time‐resolved PL, and density functional theory calculations suggest that peak A corresponds to the band‐edge transition, whereas peak B originates from the inter‐band mid‐gap states caused by selenium vacancies passivated by oxygen atoms. The comprehensive study on the PL of single‐crystalline GeSe2 sheds light on the origins of light emission in terms of the band structure of anisotropic GeSe2, making it beneficial for the corresponding optoelectronic applications. [ABSTRACT FROM AUTHOR]

The exceptional photophysical and electronic properties of 2D hybrid perovskites possess potential applications in the field of solar energy harvesting. The present work focuses on the two systems, exhibiting the Dion–Jacobson phase of 2D perovskite consisting of methylammonium (MA) and formamidinium (FA) cations at A‐site and 3‐(aminomethyl)pyridinium (3AMPY) as ring‐shaped organic spacer. Altering A‐site cations creates a distortion of inorganic layers and hydrogen bond interactions. It has been noted that the angles of Pb–I–Pb and I–Pb–I are more symmetric (close to 180°) for (3AMPY)(MA)Pb2I7 compared to (3AMPY)(FA)Pb2I7 and result in increase of bandgap from 1.51 to 1.58 eV. This further leads to a significant difference in Rashba splitting energy under the influence of spin‐orbit coupling effects, where the highest splitting (36 meV) is calculated for conduction band edge of the (3AMPY)(FA)Pb2I7, suggesting the promising applications toward spintronics. The calculated absorption spectra cover the range from 300 to 450 nm, indicating significant optical activity of 2D (3AMPY)(MA)Pb2I7 and (3AMPY)(FA)Pb2I7 in the visible and ultraviolet regions, which bodes well for their application in advanced optoelectronic devices. The bandgap and high absorption coefficients present more than 30% of theoretical power conversion efficiency for both systems, as calculated from the spectroscopic‐limited maximum efficiency. [ABSTRACT FROM AUTHOR]

Hybrid metal halides are emerging semiconductors as promising candidates for optoelectronics. The pursuit of hybridizing various dimensions of metal halides remains a desirable yet highly complex endeavor. By utilizing dimension engineering, a diverse array of new materials with intrinsically different electronic and optical properties has been developed. Here, we report a new family of 2D‐0D hybrid bimetallic halides, (C6N2H14)2SbCdCl9 ⋅ 2H2O (SbCd) and (C6N2H14)2SbCuCl9 ⋅ 2H2O (SbCu). These compounds adopt a new layered structure, consisting of alternating 0D square pyramidal [SbCl5] and 2D inorganic layers sandwiched by organic layers. SbCd and SbCu have optical band gaps of 3.3 and 2.3 eV, respectively. These compounds exhibit weak photoluminescence (PL) at room temperature, and the PL gradually enhances with decreasing temperature. Density functional theory (DFT) calculations reveal that SbCd and SbCu are direct gap semiconductors, where first‐principles band gaps follow the experimental trend. Moreover, given the different pressure responses of 0D and 2D components, these materials exhibit highly tunable electronic structures during compression, where a remarkable 11 times enhancement in PL emission is observed for SbCd at 19 GPa. This work opens new avenues for designing new layered bimetallic halides and further manipulating their structures and optoelectronic properties via pressure. [ABSTRACT FROM AUTHOR]

Within the framework of density functional theory, electronic structures of Linde‐type A (LTA) zeolite membranes are calculated, and based on the electronic structures, several key optical properties of LTA zeolite membranes can be conveniently determined, with the method of the full‐potential linearized augmented plane wave under the random phase approximation for the boundaries and the generalized gradient approximation for the exchange–correlation potentials. The calculated optical properties as a function of frequency include the real and imaginary parts of the dielectric function ε(ω), the refraction index n(ω), the extinction coefficient k(ω), the reflectivity R(ω), the energy loss function L(ω), the absorption coefficient α(ω), and finally the optical conductivity σ(ω), along with specific directions of the primitive cell. It is demonstrated that the optical properties of the sodium LTA zeolite cluster appear anisotropic within the range of UV. The nature of anisotropy implies that all the functions are 3 × 3 tensors with nonzero off‐diagonal elements. Three diagonal and three off‐diagonal elements are simultaneously presented. [ABSTRACT FROM AUTHOR]

In recent years, lead‐free double perovskite materials have attracted much attention due to their probable applications in photovoltaic and optoelectronic devices. In this work, the electronic and optical properties of lead‐free double perovskites A2BCl6 (A = Rb, Cs; B = Si, Ge, and Sn) are studied using density functional theory (DFT) methodology. The result shows that the highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO‐LUMO) energy gaps of these compounds vary between 0.524 and 0.919 eV, which agrees with the previously reported data. HOMO‐LUMO gap for Rb2SiCl6 is observed as 0.919 eV, which falls in the optimal energy gap range, that is, 0.9 to 1.6 eV for double perovskite material. Conceptual DFT‐based descriptors—molecular hardness, softness, electronegativity, electrophilicity index, and dipole moment of these compounds—are studied. The tolerance factor of A2BCl6 is observed in the range of 1.00 to 1.26. Rb2SnCl6 is almost a perfect fit with a value of 1.00. Cs2SiCl6 shows the maximum value of the refractive index and dielectric constant. Optical electronegativity is found between 0.178 and 0.246 eV. The suitable band gap and high value of the refractive index and dielectric constant make double perovskites A2BCl6 effective for solar cells and optoelectronic devices. [ABSTRACT FROM AUTHOR]

The most promising candidates for solar cells and optoelectronic devices are the transition metals dichalcogenides. Here, we employed the well‐known density functional theory to examine the structural, optoelectronic, and elastic characteristics of novel binary chalcogenides. A direct band gap for ZrX2 and an indirect band gap for PtX2 materials were both confirmed by the band structure features. The valence and conduction band regions are formed by the interaction of the A‐d and X‐p bands. Both the formation energy and the cohesive energies are calculated. The phonon dispersion plots confirmed the stability of the structures. Furthermore, the significant optical constants are computed and explained for possible employment in the optoelectronic application. Our computed band gaps and refractive index were found to be inversely associated. The vital elastic properties are also calculated to discuss the mechanical stability of these materials. The greater bulk modulus and Young's modulus for ZrS2 as compared to the studied chalcogenides suggest this material to be harder and more compressible. The B/G values, confirm all the studied dichalcogenides to be ductile. The most ductile of these materials was ZrSe2 with a predicted B/G value of 7.65. The present work could primarily aid in the creation of diverse and potentially useful semiconducting devices and their applications. [ABSTRACT FROM AUTHOR]

The gallium antimonide (GaSb) material has very attractive electronic and optoelectronic properties which are suitable for next‐generation infrared (IR) photodetector applications. In this work, properties of undoped GaSb material such as density of states, bandstructure, electron density, absorption coefficient, dielectric function, refractive index, and extinction coefficient are calculated using density‐functional theory (DFT). Moreover, the effects of doping with Ge, Sn, and Zn elements on these properties of GaSb material are investigated. It is found that undoped GaSb material exhibits a direct gap of ≈0.72 eV. Among different doping elements, Ge‐doped GaSb produces a very significant enhancement in optical properties. The Ge‐doped GaSb demonstrates a four times higher absorption coefficient in comparison to undoped GaSb in the IR region at 0.8 eV photon energy. GaSb‐based photodetector device is designed using the Solar Cell Capacitance Simulator (SCAPS) 1D tool. The efficiency of the designed photodetector with optimum thicknesses and doping of different layers is found to be improved from 21.34% to 25.91% after incorporating the absorption data set obtained from the DFT calculations. Additionally, the photodetector with optimum parameters demonstrates maximum responsivity of value ≈0.31 A W−1. In the previous findings, it is demonstrated that GaSb is a very suitable material for next‐generation IR photodetector applications. [ABSTRACT FROM AUTHOR]

The optoelectronic and magnetic features of La1−xVxAlO3 (x = 12.5, 25, 50, 75%) perovskites are investigated within density functional theory (DFT) using generalized gradient approximation by Perdew–Burke–Ernzerhof (PBE–GGA). The effect of different percentages of vanadium (V) substitution on the properties of LaAlO3 is studied and stability is confirmed through formation energies. The spin‐polarized band structure of La1−xVxAlO3 (x = 12.5, 25, 50, 75%) elucidates their half‐metallic ferromagnetic character. Furthermore, the optical performance of the given compounds is explored by optical parameters like dielectric function, optical conductivity, refractive index, reflectivity, absorption, and extinction coefficients. The obtained results make these compounds suitable for optoelectronic applications. It is observed that the determined magnetic moment in La1−xVxAlO3 is mainly due to the V‐3d states. The regulated reduction in bandgap (Eg) with the upsurge of V doping and half‐metallic ferromagnetic nature makes them appropriate for spintronic and magnetic devices. [ABSTRACT FROM AUTHOR]

First‐principles calculations based on density functional theory (DFT) are used to investigate the phase transition characteristics, electronic structures, and optical properties of pure and Co‐doped VO2 (M1 and R phase). Studies show that the metal‐to‐insulator phase transition temperature of VO2 is significantly reduced after Co doping, which is correlated to the decrease of bandgap value. Besides, the decrease of the energy required for electron transition of M1‐phase Co‐doped VO2 corresponds to the imaginary part of the dielectric peak moving to the low‐energy region. For both the M1‐ and R‐phase VO2, the visible light transmissivity of the Co‐doped VO2 is increased than that of pure VO2, which is beneficial to the application of VO2 film as visible windows. In addition, the absorptivity and reflectivity of Co‐doped R‐phase VO2 in the infrared light range are larger than those of M1‐phase VO2, indicating that the Co‐doped VO2 can block more infrared light at higher temperature to fulfill the purpose of lowering temperature. Overall, these results give new insights for the application of Co‐doped VO2 as a photoenergy material to regulate the room temperature. [ABSTRACT FROM AUTHOR]

Herein, the biaxial strain effect is investigated on the structural, electronic, and optical properties of 1T and 1H phases of Janus CaFBr monolayer in the framework of density functional theory. It is found that both phases of the Janus CaFBr monolayer are direct semiconductors at equilibrium, with bandgaps of 3.90 and 3.55 eV for 1T and 1H phases, respectively. The thermodynamic stability is examined via cohesive energy and phonon dispersion. The bandgap decreases linearly and is nearly parabolic for 1T and 1H phases, respectively, when switching from the tensile to compressive strain with a drastic shift from direct to indirect bandgap at −10% of compressive strains. The calculated dielectric function and optical properties such as reflectivity, refractive index, extinction, and absorption coefficients enhance under biaxial with an improvement of the absorption coefficient especially in the visible and ultraviolet (UV) regions for 1H and 1T phases, respectively, which is in line with the dielectric constant. The results suggest that the Janus CaFBr monolayer might be a potential candidate for optoelectronic applications in visible/UV detection and absorption. [ABSTRACT FROM AUTHOR]

The present study investigates the influence of layer thickness and stacking engineering on the electronic, structural, and optical properties of monolayer PtS2 using the density functional theory calculations. The monolayer PtS2 (m‐PtS2) is found to possess an indirect bandgap, 1.73 eV, which reduces to 0.67 eV for bilayer PtS2 (b‐PtS2). Impact of stacking engineering on the electronic and optical properties is explored through six different stacking patterns and the AA1 configuration is found to be most stable displaying the highest reflectance and refractive index values. Moreover, this PtS2 bilayer structure demonstrates promising light absorption capability over a wide range (2–12 eV) with the position of absorption edge showing a redshift as the layers number increases. These computed electronic and optical properties of monolayer PtS2 validate it as a prospective material for future optoelectronic devices. [ABSTRACT FROM AUTHOR]

Chiral materials are attracting considerable interest in various fields in view of their unique properties and optical activity. Indeed, the peculiar features of chiral materials to absorb and emit circularly polarized light enable their use in an extensive range of applications. Motivated by the interest in boosting the development of chiral materials characterized by enhanced chiroptical properties such as circular dichroism (CD) and circular polarized luminescence (CPL), we herein illustrate in this tutorial how theoretical simulations can be used for the predictions and interpretations of chiroptical data and for the identification of chiral geometries. We are focusing on computational frameworks that can be used to investigate the theoretical aspects of chiral materials' photophysical and conformational characteristics. We will then illustrate ab initio methods based on density functional theory (DFT) and its time‐dependent extension (TD‐DFT) to simulate CD and CPL signals, and we will exemplify a variety of enhanced sampling techniques useful for an adequate sampling of the configurational space for chiral systems. [ABSTRACT FROM AUTHOR]

Herein, the density functional theory is used to study the structural, mechanical, electrical, optical, and hydrogen evolution reaction (HER) properties of monolayer structures (α,β)–S2C2N2$\left(\right. \alpha , \beta \left.\right) – \left(\text{S}\right)_{2} \left(\text{C}\right)_{2} \left(\text{N}\right)_{2}$ and (α,β)–SCN/CN$\left(\right. \alpha , \beta \left.\right) – \text{SCN} / \text{CN}$. They are claimed to be stable monolayer structures by phonon dispersion and ab initio molecular dynamics (AIMD). Compared to graphene (≈340 N m−1), the (α,β)–SCN/CN$\left(\right. \alpha , \beta \left.\right) – \text{SCN} / \text{CN}$ shows a higher Young's modulus (≈429, 414 N m−1). Moreover, the piezoelectric stress coefficient of α‐SCN/CN$\text{SCN} / \text{CN}$ (d11$d_{11}$=2.65 pm V−1) is comparable with bulk piezoelectric α‐quartz (d11$d_{11}$=2.3 pm V−1). Exciton effect at M point causes redshift and enhancement of light absorption of α‐SCN/CN$\text{SCN} / \text{CN}$ and β–SCN/CN$\beta – \text{SCN} / \text{CN}$. The overpotential of β–SCN/CN$\beta – \text{SCN} / \text{CN}$ is only –0.072 V. Besides, the (α,β)–SCN/CN$\left(\right. \alpha , \beta \left.\right) – \text{SCN} / \text{CN}$ gives a small effective electron mass of about 0.2(m0). It is worth mentioning that the monolayer structures (α,β)–S2C2N2$\left(\right. \alpha , \beta \left.\right) – \left(\text{S}\right)_{2} \left(\text{C}\right)_{2} \left(\text{N}\right)_{2}$ show the semimetal phases. Due to the unique semimetal phase, the absorption of β–S2C2N2$\beta – \left(\text{S}\right)_{2} \left(\text{C}\right)_{2} \left(\text{N}\right)_{2}$ has an excellent performance in the near‐infrared (NIR) region. It can be enhanced at the NIR region and extended to the middle infrared region when applying tensile stress. These results provide more choices for 2D materials in electrocatalysis, piezoelectric sensors, visible light devices, and infrared photodetectors. [ABSTRACT FROM AUTHOR]

First‐principles calculations based on density functional theory (DFT) are used to investigate the phase transition characteristics, electronic structures, and optical properties of pure and Co‐doped VO2 (M1 and R phase). Studies show that the metal‐to‐insulator phase transition temperature of VO2 is significantly reduced after Co doping, which is correlated to the decrease of bandgap value. Besides, the decrease of the energy required for electron transition of M1‐phase Co‐doped VO2 corresponds to the imaginary part of the dielectric peak moving to the low‐energy region. For both the M1‐ and R‐phase VO2, the visible light transmissivity of the Co‐doped VO2 is increased than that of pure VO2, which is beneficial to the application of VO2 film as visible windows. In addition, the absorptivity and reflectivity of Co‐doped R‐phase VO2 in the infrared light range are larger than those of M1‐phase VO2, indicating that the Co‐doped VO2 can block more infrared light at higher temperature to fulfill the purpose of lowering temperature. Overall, these results give new insights for the application of Co‐doped VO2 as a photoenergy material to regulate the room temperature. [ABSTRACT FROM AUTHOR]

Thermoelectric materials have an important role in electronic chips due to their capability of heat and electricity interconversion. Here we investigated thermoelectric properties of Zn3As2 and ZnSb by using density functional theory combined with the Boltzmann transport equation. We evaluated the well‐known thermoelectric figure of merit (ZT) of both materials and found a maximum ZT of 0.09 and 0.27 for Zn3As2 and ZnSb at 200°C and 1000°C, respectively. While investigating the electronic properties, we found that Zn3As2 has a direct band‐gap at the Γ‐point of 1.01 eV, while ZnSb has an indirect bandgap of 0.65 eV. Both materials exhibited high optical absorption and reflectivity in the visible and UV regions, which suggest that these materials are beneficial in photovoltaic cells, along with thermoelectric applications. [ABSTRACT FROM AUTHOR]

Herein, the electronic, thermoelectric, and optical properties of semimetallic HPX6 (X = C, Si, Ge, Sn) monolayers are systematically studied under the influence of external electric field in the framework of density functional theory. A band tuning has been achieved in these structures by the application of an external electric field of appropriate strength. It is predicted that Dirac cone splitting is nearly proportional to the external electric field strength. The modulation of electric properties induced by external field can alter the position of chemical potential in the band diagram and brings significant improvement in thermoelectric responses. The application of an external electric field significantly modulates the optical properties. The electric field‐induced HPX6 system provides better thermoelectric and optical response for nanodevice applications. [ABSTRACT FROM AUTHOR]

Herein, the comprehensive study of different properties of undoped MoS2, MoS2 lattice with sulfur (S) and, molybdenum (Mo) vacancy, and MoS2 with substitutional doping of niobium (Nb), vanadium (V), and zinc (Zn) atoms is done. The density functional theory (DFT) is used and the electronic properties like density of states, band structure, electron density, and optical properties like dielectric function, optical conductivity, and refractive index are studied. It is observed that undoped MoS2 monolayer shows direct bandgap semiconductor characteristics with a bandgap of around 1.79 eV. P‐type characteristics are observed for Nb‐, V‐, and Zn‐doped MoS2 lattices. The real part and imaginary parts of all optical parameters along x and z directions for different MoS2 supercells are found to be anisotropic in nature up to a photon energy of almost 11 eV and thereafter they show nearly isotropic nature. Finally, it is found that the obtained properties of MoS2 monolayer as per literature are suitable for next‐generation MOSFET application. [ABSTRACT FROM AUTHOR]

Herein, the comprehensive study of different properties of undoped MoS2, MoS2 lattice with sulfur (S) and, molybdenum (Mo) vacancy, and MoS2 with substitutional doping of niobium (Nb), vanadium (V), and zinc (Zn) atoms is done. The density functional theory (DFT) is used and the electronic properties like density of states, band structure, electron density, and optical properties like dielectric function, optical conductivity, and refractive index are studied. It is observed that undoped MoS2 monolayer shows direct bandgap semiconductor characteristics with a bandgap of around 1.79 eV. P‐type characteristics are observed for Nb‐, V‐, and Zn‐doped MoS2 lattices. The real part and imaginary parts of all optical parameters along x and z directions for different MoS2 supercells are found to be anisotropic in nature up to a photon energy of almost 11 eV and thereafter they show nearly isotropic nature. Finally, it is found that the obtained properties of MoS2 monolayer as per literature are suitable for next‐generation MOSFET application. [ABSTRACT FROM AUTHOR]

Organic–inorganic metal halides (OIMHs) with high‐efficiency solar spectrum‐like emission are attracting broad and current interest. Here, five 0D Zn‐based hybrid halides are synthesized based on aromatic organic cations with different carbon‐chain lengths: C6H5CH2NH3+ (PMA+) and C6H5(CH2)4NH3+ (PBA+). (PMA)2ZnCl4 exhibits the highest photoluminescence quantum yield of 37.2% of reported Zn‐based white‐emission OIMHs. The emission spectrum of (PBA)2ZnI4 indicates a color rendering index of 98, which is the highest among single‐component white‐light‐emitting phosphors. Spectral characterizations and density functional theory calculations demonstrate that the extremely broad emission of (PBA)2ZnI4 originates from the synergistic emission of organic cations and self‐trapped excitons. The optical properties of the obtained (PMA)2ZnBr4, (PMA)2ZnI4·H2O, and (PBA)2ZnCl4 are also characterized for comparison, and with the same organic cations, the PLQY decreases from chloride to bromide to iodide. This work demonstrates that the selection of appropriate organics and halogens can enable fine tuning of single‐component white‐light emission, satisfying varying needs for solid‐state lighting. [ABSTRACT FROM AUTHOR]

The structural, electronic, magnetic, and optical properties of MFe2O4 (M = Ni, Fe, Co) ferrites were investigated by employing Cambridge Serial Total Energy Package code using density functional theory. LDA+U was used to investigate the structural, electronic, magnetic, and optical properties of MFe2O4 (M = Ni, Fe, Co) ferrites at different pressures 0, 5, 10, 15, and 20 GPa. The simulated X‐ray diffraction (XRD) pattern of MFe2O4 (M = Ni, Fe, Co) ferrites was investigated and the computed lattice parameters decreased 8.62–8.32, 8.68–8.35, and 8.567–8.267 Å at 0–20 GPa, respectively. XRD revealed that the unit cell's volumes (640.50–575.93, 653.97–582.182, 627.22–563.550), X‐ray densities (4.86–5.40, 4.70–5.28, 3.97–4.43), and interatomic distance (2.6099–2.5180, 2.6221–2.4260, 2.5831–2.4928) of MFe2O4 (M = Ni, Fe, Co) ferrites were also decreased with the increasing pressure 0–20 GPa, respectively. The LDA+U calculations predicted that the NiFe2O4, Fe3O4, and CoFe2O4 ferrite followed the properties of a semiconductor exhibiting a direct band gap of 1.2, 1.13, and 0.710 eV at 0 GPa which were decreased to 0.846, 0.710, and 0.461 eV at 20 GPa, respectively. The computed density of states revealed that MFe2O4 (M = Ni, Fe, Co) ferrites exhibited good spin polarization behavior, and Ni–O, Fe–O, and Co–O bonds were covalent. The Mullikens investigated the ted decrease in bong length of MFe2O4 (M = Ni, Fe, Co) ferrites versus 0–20 GPa as well as according to Hirschfeld analysis the magnetic moment (3.348–3.335, 4.12–4.10, 3.737–3.735) and saturation magnetization (79.06–78.7, 99.33–98.9, 88.93–88.352) of MFe2O4 (M = Ni, Fe, Co) ferrites were decreased with increased pressure 0–20 GPa, respectively. The reflectivity and absorption specialize in visible and ultraviolet regions showing their stability for optoelectronics, photocatalysis, and solar cell applications. [ABSTRACT FROM AUTHOR]

Vacancy defects in two‐dimensional (2D) materials are critical to their properties. The substitutional doping in vacancy defects by rare‐earth atoms results in diverse material versatilities, but the effects and the corresponding mechanisms are far from being answered. Herein, the electronic and optical properties of vacancy defects and lanthanide rare‐earth (RE = Er, Tm, Lu) doping in WS2 monolayers are studied based on density functional theory with Hubbard correction (DFT + U). The formation energies of defective and doped systems are calculated under W‐rich and S‐rich conditions, respectively. The bandgap of WS2 with one W‐defect in a 4 × 4 × 1 supercell changes from direct to indirect, while S‐defect does not change the bandgap type of the supercell. When RE atoms are doped in the W‐defect, the bandgap returns to direct. WS2 supercells with intrinsic defects and Lu doped in [W] defect show the nonmagnetic property, while Er‐ and Tm‐doped supercells show obvious magnetic properties. The imaginary part of dielectric function and absorption coefficients increase drastically from visible to near‐infrared as RE atoms substitute W sites, and the bandgap shrinks due to the rise of the valance band maximum. This work proves RE doping in 2D WS2 is an effective technique for bandgap and carrier engineering. [ABSTRACT FROM AUTHOR]

Here, we study the dielectric and optical properties of two‐dimensional (2D) WX2 monolayers, where X is Cl, O, S, Se, and Te. First principle electronic band structure calculations reveal that all materials are direct band gap semiconductors except WO2 and WCl2, which are found to be indirect band gap semiconducting 2D materials. The dielectric response of these materials is also systematically investigated. The obtained results suggest that these materials are suitable as dielectric materials to suppress unwanted signal noise. The optical properties of these 2D materials, such as absorption, reflection and extinction coefficients, refractive index, and optical conductivity, are also calculated from the dielectric function. It is found that these materials exhibit excellent optical response. The present electronic, dielectric, and optical findings indicate that WX2 monolayers have an opportunity in electronic, optical, and optoelectronic device applications. [ABSTRACT FROM AUTHOR]

In the present work, the physical properties of alkali‐earth metal and transition metal hydroxides are comprehensively investigated using the density functional theory. Here, the alkali‐earth metals Ca, Mg, and transition metals Cd, Zn are considered from the II‐A and II‐B groups in the periodic table of elements. The first principle electronic structure calculations show that these bulk hydroxide materials are direct band gap material. Ca(OH)2 and Mg(OH)2 exhibit an insulating behavior with a very large band gap. However, Cd(OH)2 and Zn(OH)2 are found to be wide band gap semiconductors. The dielectric and optical studies reveal that these materials have a high degree of anisotropy. Hence, the light propagation in these materials behaves differently in the direction perpendicular and parallel to the optical axis, and exhibits birefringence. Therefore, these materials may be useful for optical communication. The calculated electron energy loss suggests that these materials can also be used for unwanted signal noise suppression. The wide band gap makes them useful for high‐power applications. Moreover, Ca(OH)2 and Mg(OH)2 are found to be suitable for dielectric medium. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) has been carried out to investigate the electronic characteristics, UV–VIS–NIR absorption spectra, and nonlinear optical (NLO) properties of two series of zinc porphyrin analogs (FPD‐Nx and TPD‐Nx, x = 0–4) with donor‐π‐donor frameworks. The design of these analogs is based on previously synthesized furan‐linked zinc porphyrins (FPDs) and thiophene‐linked zinc porphyrins (TPDs). It is noted that their electro‐optical features are sensitive to the numbers of N‐coordination atoms and the attached groups. A dramatic enhancement of static first and second hyperpolarizabilities (β0 and γ0) occurs when two furan/thiophene rings are attached to the zinc porphyrin. Among the two series, FPD‐N3 and TPD‐N3 have the largest β0 values of about 7600 a.u. The static γ0 values of these complexes range from 0.41 × 106 to 1.79 × 106 a.u. The FPD‐Nx has a larger γ0 value than the corresponding TPD‐Nx, but the γ0 value of FPD‐N2 is close to that of TPD‐N2. In the dynamic NLO process, the electro‐optical Pockels effect, second harmonic generation, and electro‐optic Kerr effect can be enhanced at the wavelength of 1907 nm. This study provides a new strategy for the experimental design of high‐performance NLO materials. [ABSTRACT FROM AUTHOR]