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The configurations of nine different non-metals doped silicon carbide (NM-SiC) were structured by using the density functional theory (DFT). The magnetic, electronic, and optical properties of each NM-SiC are investigated at the most stable structure with the maximum binding energy. Although the O-, Si-, and S-SiC systems are still non-magnetic semiconductors, the N- and P-SiC systems have the properties of the magnetic semiconductors. The H-, F-, and Cl-SiC systems exhibit the half-metal behaviors, while the B-SiC system converts to magnetic metal. The redistribution of charges occurs between non-metals atoms and adjacent C atoms. For the same doping position, the more charges are transferred, the greater the binding energy of the NM-SiC system. The work function of the NM-SiC systems is also adjusted by the doping of NM atoms, and achieves the minimum 3.70 eV in the P-SiC, just 77.1% of the original SiC. The absorption spectrum of the NM-SiC systems occurs red-shift in the ultraviolet light region, accompanying the decrease of absorption coefficient. These adjustable magnetic, electronic, and optical performances of NM-SiC expand the application fields of two-dimensional (2D) SiC, especially in designing field emission and spintronics devices.

The main objective of this research was to design non-fullerene acceptors (NFAs) A--D--A framework, using carbazole and benzothiazole derivatives. Density functional theory (DFT) was used to calculate the geometry optimized structures and electronic properties at B3LYP functional with a 6-311G basis set in the gas and solvent phase. The frontier molecular orbitals (FMO), bandgap, open-circuit voltage (VOC) and dipole moments of these developed acceptors have been calculated. The theoretical UV absorption spectra were calculated from time-dependent DFT with the same level of theory used DFT method. They show a suitable bandgap (2.24-2.93 eV) and dipole moment (1.8-10.8 Debye). The maximumwavelength (λmax) for all studied molecules in the range is 665.17-679.97 in both gas and solvent. A slight redshift was observed in all acceptors selected for chlorobenzene compared with gas phase absorption. The NFA A11 has the lowest bandgap energy (2.24 eV), gas-phase excitation energy (1.86 eV) and chlorobenzene excitation energy (1.86 eV). As a result, A11 is predicted to be a good contender for organic NFAs in the future. The open-circuit voltage (VOC) values range from 1.53 to 2.56 eV. Consequently, the optoelectronic, molecular orbital distribution and A11 and A12 molecules were suitable acceptors for NFAs. [ABSTRACT FROM AUTHOR]

[Display omitted] The electronic and optical properties of finite silicene, graphene, and arsenene heterostructures are investigated using first principles calculations. The optoelectronic properties of these structures are precisely controlled, by chemical functionalization, shape, and size, to produce suitable donor energy gap and minimal conduction band offset that enable the construction of efficient heterojunction solar cells. Heterojunctions with only Van der Waals interactions between layers have been achieved in functionalized silicene/graphene and arsenene/graphene. The distribution of the highest occupied/lowest unoccupied molecular orbital on donor/acceptor layer in addition to the contribution of each layer into the total electronic density of states insure that the only interlayer interaction is the van der Waals one and charge separation is attained. The heterojunctions have donors' energy gaps ranging from 1.2 to 1.8 eV which in conjunction with the very low conduction band offset ∼ 0.002 eV enable the building of type-II solar cells with extremely high power conversion efficiency up to 23.34%. The prominent low energy optical excitations are mainly contributed by a transition from donor molecular orbitals to acceptor ones. Therefore, functionalized 2D heterojunctions are excellent candidates for building ultrathin, stable, and low-cost efficient solar cells. [ABSTRACT FROM AUTHOR]

The recent successful synthesis of Pnnm -CN structure inspired researchers to explore new superhard 3D C–N compounds via a similar method, that is, high-pressure and high-temperature experiments involving carbon and nitrogen elements. Naturally, in some past high-pressure experiments involving C–N precursors, whether there are undiscovered C–N compounds in the product is worthy of being re-examined. This work proposed four novel carbon-rich C–N compounds, namely, r -C 17 N 4 , sc -C 4 N, sc -C 17 N 4 –I, and sc -C 17 N 4 -II, which possibly coexist with the unidentified simple cubic carbon phase in the shock compression products of the carbon black and tetracyanoethylene mixture. Most of the X-ray diffraction peaks from the experiment could be understood by the proposed C–N compounds. Furthermore, the calculations of formation enthalpies using experimental materials as precursors show that these four C–N compounds are more easily synthesized than the carbon structures previously used to explain the unknown phase. These phenomena indicate that C–N compounds might be synthesized in this experiment, not just the new carbon phase. The current study may provide a new idea for the experimental research of C–N compounds and inspire further research to reevaluate previous experimental findings. [Display omitted] [ABSTRACT FROM AUTHOR]

In order to explore the practicability of β-Ga1.9375Mg0.0625O3 (100) surface as photoemission material, the structural stability, electronic and optical properties of Cs on β-Ga1.0975Mg0.0625O3 (100) surface are calculated by the first principles calculation. The adsorption structure is the most stable when Cs atom on the top of Mg atom. It is found that Cs adsorption on β-Ga1.0975Mg0.0625O3 (100) surface can reduce work function duo to the existence of dipole moment and generate slight band bending. The adsorption edge rapidly increases at 205 nm, which means that Cs/β-Ga1.9375Mg0.0625O3 (100) surface is a potential optical material at DUV region. [ABSTRACT FROM AUTHOR]

BeO is a large band gap semiconductor with remarkably electronic, thermal and optical properties, being a potential material for nanodevices. In this work, using first principles calculations within the density functional theory and molecular dynamics simulations, we show that BeO is stable in the planar form (single-layer and single walled nanotubes). These nanostructures exhibit a large band gap (≈ 6 eV), being useful to host localized states. The stability of BeO layers upon the presence of native defects (vacancies and antisites) are investigated by calculating the formation energies as a function of the Fermi energy. The results have shown that in the neutral charge states, vacancies (V O and V B e) are the most likely defects to occur. For charge states, the defect stability is ruled by the Fermi energy position. The electronic band structure shows that natives defects give rise to spin localized electronic levels inside the band gap, which are stable in different charge states and can be thermally ionized. Furthermore, we investigate the optical properties (optical absorption spectra) and spin state (spin magnetic moments) for all stable defects. We observed that the spin localized states in the ground states lead the BeO layer materials to host quantum defects, which can be useful in quantum information. [Display omitted] • Layered BeO structures present a large band gap. • Native defects (vacancies and antisites) give rise to new electronic levels inside the band gap. • Native defects in layered BeO can be useful to generate localized states in the bandgap. • The stability and spin magnetic moments depend on the charge state. • Native defects in BeO layers can be considered as quantum defects. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT)-D3 dispersion corrections and molecular dynamic (MD) techniques were used to research how curcumin (CUR) and poly (lactic-co-glycolic acid) (PLGA) interact in the water phase. Relaxation based on machine learning (ML) algorithms was used to identify the state configuration that was the most stable. The electronic, optical, and infrared (IR) vibrational properties of the studied configurations were then computed. The findings show that since PLGA nanoparticle can transport CUR via chemical interactions, the binding energy of CUR through carbonyl group to PLGA is about −1.092 eV (complex A). The theoretical IR spectrum supports the observation that the functional groups of CUR interacting with PLGA undergo changes, which is consistent with the experimental data. Hence, the Bader charge analysis indicates a charge of about 0.14 (complex A) and 0.17 (complex B) |e| transferred from the PLGA to CUR. The charges in CUR exhibit strong charge transfer to the PLGA structure. The calculated results of the CUR-PLGA complex match the main peak in the 500–580 nm range observed in experiments, and the stable optimal optical absorption diagram aligns with the reported spectra. The total density of states (TDOS) of the studied configurations shows that CUR is having an impact on the HOMO and LUMO levels. The PLGA nanoparticle demonstrates a higher sensitivity (86%) towards the presence of CUR in complex D compared to complex B (67%), which can be attributed to the change in the energy gap. This low adsorption energy and high sensitivity suggest that the PLGA nanoparticle indicates its potential to serve as both a carrier and a sensor for detecting CUR in the water phase. [Display omitted] • Investigation of Curcumin Interaction with PLGA Microparticles using DFT and TDDFT Simulations. • DFT results demonstrate strong hydrogen bonding between curcumin and PLGA. • PLGA microparticles show potential as drug delivery nanocarriers. • PLGA enhances dipole moment and reduces the energy gap. [ABSTRACT FROM AUTHOR]

[Display omitted] • TiO 2 quantum dots (QDs) modified asphalt has been proposed as an innovative cool pavement technology. • Electronic and optical characteristics of TiO 2 QDs are investigated based on quantum mechanics calculations. • Modification mechanism and properties of TiO 2 QDs modified asphalt are evaluated based on molecular dynamics simulations. • Impacts of quantum sizes and concentrations on properties of TiO 2 QDs modified asphalt are analyzed. With exceptional solar reflectivity and fluorescent characteristics, TiO 2 quantum dots (QDs) modified asphalt has been proposed as an innovative cool pavement technology. However, interaction mechanism and thermodynamic properties of TiO 2 QDs modified asphalt at microscale have not been well understood. In this study, electronic and optical properties of TiO 2 QDs with varied sizes were investigated based on quantum mechanics (QM) calculations. Moreover, molecular dynamics (MD) simulations were implemented to evaluate mechanical moduli and intermolecular dynamics of TiO 2 QDs modified asphalt with different quantum sizes and concentrations. The results from QM calculations unveil that as size of TiO 2 QDs rises from 6 Å to 12 Å, energy gap and binding energy of TiO 2 QDs decreases by 0.928 eV and 526.38 eV, respectively while density of state (DOS) and absorption coefficient of TiO 2 QDs increases. Besides, the results from MD simulations reveal that quantum size imposes significant impact on mechanical moduli of modified asphalt while concentration of TiO 2 QDs brings notable influence on interaction between quantum dots and asphalt. Specifically, as concentration of QDs rises from 10 % to 30 %, cohesive energy density (CED) and solubility parameter (SP) of modified asphalt is improved by up to 457 % and 136 %, respectively. With increasing quantum size, bulk modulus, shear modulus, and Young's modulus of modified asphalt is enhanced by up to 372 %, 206 % and 24 %, respectively. The outcomes of this study provide insights into formula and application of advanced asphalt pavement with TiO 2 QDs. [ABSTRACT FROM AUTHOR]

Strontium phosphorus iodide (Sr 3 PI 3) has attracted interest as a possible absorber material because of its unique optical, electronic, and structural properties, which make it appropriate for effective and reasonably priced solar cell applications. With an emphasis on its structural, optical, and electronic characteristics, this paper thoroughly examines the theoretical aspects of Sr 3 PI 3 before investigating its possible uses in heterostructure solar cells. The optoelectronic characteristics of the novel Sr 3 PI 3 absorber are first investigated, and a DFT analysis is conducted to determine appropriate electron transport layer (ETL) materials, including tin sulfide (SnS 2), zinc sulfide (ZnS), and indium sulfide (In 2 S 3), as well as different interface layers. The photovoltaic (PV) performance of cell architectures based on the Sr 3 PI 3 absorber with SnS 2 , ZnS, and In 2 S 3 as ETLs is then thoroughly investigated. Variations in layer thickness, defect density, bulk and doping density, active material interface density, working temperature, and other parameters are investigated in this study. By using the SCAPS-1D simulator, PV parameter optimization is accomplished. In addition, the study examined the generation and recombination rates of photocarriers, quantum efficiency (QE), and current density-voltage (J-V) properties. The structure with the highest power conversion efficiency (PCE) of 27.32% was the Al/FTO/SnS 2 /Sr 3 PI 3 /Ni combination. It achieved a J SC of 36.1146 mAcm−2, FF of 84.06%, and V OC of 0.899 V for the SnS 2 ETL. In contrast, the PCEs in heterostructures for ZnS and In 2 S 3 ETLs were 20.13 % and 17.87 %, respectively. The physical, electrical, and optical characteristics of SnS 2 , ZnS, and In 2 S 3 ETLs, as well as Sr 3 PI 3 perovskite absorbers are better understood as a result of this work. Furthermore, it provides insightful information about the possible use of Sr 3 PI 3 in heterostructure perovskite solar cells (PSCs), laying the groundwork for future experimental plans intended to create stable and effective PSCs. • Using FP-DFT, the structural, electrical, and optical characteristics of new inorganic cubic perovskites of Sr 3 PI 3 were thoroughly examined. • Sr 3 PI 3 absorber's potential has been methodically examined and assessed at different layer thicknesses, defect densities, and doping levels using In 2 S 3 , SnS 2 , and ZnS electron transport layers (ETLs). • Using SCAPS-1D, the photovoltaic performance of the Sr 3 PI 3 absorber-based structure was examined. • For the Al/FTO/SnS 2 /Sr 3 PI 3 /Ni structure, the maximum power conversion efficiency was found to be 27.32% with a J SC of 36.1146 mAcm−2, FF of 84.06%, and V OC of 0.899 V. [ABSTRACT FROM AUTHOR]

The electronic and optical properties of Janus Ga2SSe monolayer are tuned by adsorption of metals like Au, Ag, Al and Cu over Ga2SSe layer using density functional theory-based simulations. The results suggest that the absorption in pristine Ga2SSe monolayer is mainly in the blue region of the visible spectrum. The absorption peaks increase in magnitude and shift towards the red region of the spectrum when Au, Ag, Al, and Cu metal atoms are adsorbed over the pristine Ga2SSe monolayer. The absorption peaks in Al adsorbed structure are observed to increase four times larger in magnitude than in pristine Ga2SSe layer. Significantly higher absorption is observed in other structures as well with the absorption peaks spread in the entire visible region range (~ 410–790 nm). Refractive index and dielectric function of all structures are also calculated, and it is found that absorption is closely in line with the trends of the dielectric function. High absorption obtained in the entire visible region in the metal adsorbed structures suggest their potential applications in photovoltaic absorbers and other optoelectronics devices. [ABSTRACT FROM AUTHOR]

ThO2 (thoria) is an important semiconductor, optical material, and mineral. It has Fm 3 - m phase at normal pressure, and it transforms to the Pnma phase under high pressure. The electronic and optical properties of ThO2 are important and urgent to study for its applications. Since the exhaustive optical properties of ThO2 are scarce, we used the GGA + U method to calculate the electronic and optical properties of ThO2 at normal pressure as well as under high pressure in detail. Our calculated band gap of Fm 3 - m phase increases with increasing pressure, while that of the Pnma phase nearly keeps constant. A blue shift in optical properties is found with increasing pressure. We discussed the relation between the band, the imaginary part of the dielectric function, and the density of states. We also used proper equations to fit the relation between band gap, absorption coefficient, and pressure. The acquired properties under pressure indicate phase transition as well as having application significance. Our studies not only stimulate the related researches but also pave a road for future application of ThO2 in the field of geosciences, physics, and materials. [ABSTRACT FROM AUTHOR]

First-principles calculations have been carried out to explore the zinc and mercury composition-dependent structural, elastic, electronic, and optical properties of zinc-blend specimens under the Cd1−x−yZnxHgyS triangular quaternary system. Each quaternary alloy shows thermodynamic stability. Computed elastic stiffness constants confirm the mechanical stability, ductility, elastic anisotropy, compressibility, plasticity, and mixed type of bonding in each specimen. Calculations with modified Becke–Johnson (mBJ)-generalized gradient approximation (GGA) and GGA+U schemes show that each ternary or quaternary alloy is a direct band gap (Γ–Γ) semiconductor. Carrier transportation in each specimen is significantly dominated by electrons due to their much lower effective mass compared to holes. Electronic transitions from the occupied S-3p state of the valence band to the unoccupied Zn-5s, Cd-6s, and Hg-7s states of the conduction band are exclusively or collectively responsible for the occurrence of intense peaks in the imaginary part of the dielectric function, ε2(ω), spectra of the considered specimens. The calculated oscillator strengths of quaternary alloys show the presence of a sufficient number of electrons in the unoccupied states of the conduction band beyond 25.0 eV of incident energy during optical excitations. [ABSTRACT FROM AUTHOR]

Research on organic thin films is largely driven by potential (opto‐)electronic applications and turns out to be no less intriguing from a fundamental point of view. Numerous studies make it clear that the understanding of device‐relevant molecular thin film architectures is quite challenging—often hampered by insufficient spectroscopic data and the lack of a consistent interpretation of the available datasets. Consequently, speculative aspects prevail in the discussion of energy levels in conjunction with the optical properties of organic thin films. Adequate spectroscopic techniques applicable to thin films of organic molecules (typical thicknesses required for devices are in the nanometer range) with the necessary sensitivities are rather demanding. Some of those methods were developed or significantly improved in the recent past. Here, the now available complementary spectroscopies are briefly surveyed with particular emphasis on some techniques that have not yet become widespread standards, and a non‐exhaustive set of examples of acquired experimental results are provided. For a consistent interpretation of the latter, the concepts brought forward in the literature considering the role of initial and final states of spectroscopic processes are outlined, with important consequences for quantitatively correct energy diagrams. [ABSTRACT FROM AUTHOR]

Оptical and electronic properties of crystalline Li2TeO3, which is a tellurite glass, are studied in the framework of density functional theory (DFT) implemented in the software SIESTA. The material has a monoclinic symmetrized structure and the unit or primitive cell of the material, periodic in all directions, has been taken to study the properties. The electronic structures show that it is a wide-gap semiconductor, and its properties change to metallic when subjected to strong electric field. This tunable property can be used in various fields of electronics. The optical properties studied tells that Li2TeO3 can be a promising material to be used as a hole transport material (HTM) for developing efficient perovskite solar cells and other applications as well. [ABSTRACT FROM AUTHOR]

Structural, elastic and electronic properties of ZnN and ternary compound ZnN1 –xOx with the zinc-blende (ZB) structure have been studied with density functional theory (DFT). The exchange-correlation potential was calculated using the generalized gradient approximation (GGA) of Perdew–Burke–Ernzerhof (PBE) and the local density approximation (LDA) of Teter–Pade (TP). In the present work, we used the virtual-crystal approximation (VCA) to study the effect of composition (x). The calculated lattice parameters at equilibrium volume and bulk modulus for ZnN are in good agreement with theoretical results reported in the literature. The calculated band structure reveal a semiconducting behavior with a direct band gap (Г–Г) at the Fermi level for ZnN1 –xOx compounds. The measured values, for the ZnN compound are 1.762 eV using TP-LDA and 1.478 eV using PBE-GGA. In addition, we have also predicted the bulk modulus (B), shear modulus (G), Young's modulus (E), Poisson's ratio (), the sound velocity, and Debye temperature (θD). [ABSTRACT FROM AUTHOR]

Quasi-one-dimensional nanoribbons (NRs) are promising candidate materials for flexible optoelectronics with high device density. The optical properties of nanomaterials are strongly influenced by excitons, and it is important for flexible devices to explore how excitons behave under strain. In this work, we investigate the electronic and excitonic properties of bent black phosphorus (BP) NRs via density-functional theory and many-body Green's function methods. We find that inhomogeneous strain fields affect not only the first excitonic energy and thus the optical gap, but also the spatial distribution of the excitons. In particular, excitonic funnels can occur in bent black phosphorus nanoribbons (BPNRs), which drive higher-energy excitons toward lower energy locations. The funnels can be effectively tuned by the intensity and sign (compressed to tensile) of the strain field. Another critical factor is anisotropy: the funnel effect is much more pronounced in armchair BPNRs than in zigzag BPNRs. In addition, we find that the excitonic funnel effect in two-dimensional monolayer BP differs from that in multilayer BP films.

Effect of high bandgap 0. 5  nm AlAs on the electronic and optical properties of the In 0. 7 0 Ga 0. 3 0 As / Al 0. 6 0 In 0. 4 0 As superlattice is investigated by using effective mass approximation under the electric field. Electronic transitions are obtained as 0.403 eV and 0.023 eV for E 3 2 and E 2 1 in the gain region. Thin AlAs increases electron confinement in the superlattice and prevents electron leakage in the gain region which mostly results in higher absorption/emission in the superlattice. AlAs has no major effects on transitions energies in the gain region but it is effectively decreasing the total absorption in the injector region and preventing the internal absorption. AlAs also makes the superlattice optically more stable by decreasing the high refractive index change in the injector region by factor 5. [ABSTRACT FROM AUTHOR]

Structural, electronic and optical properties of Nb and F co-doped SnO 2 were mainly investigated using density functional theory (DFT). Hybrid density functional theory was employed to obtain band structure, density of states (DOS) and optical properties. The calculated lattice parameters of pure SnO 2 by PBEsol functional (a = 4.774 Å and c = 3.218 Å) are in good agreement with experimental date (a = 4.742 Å and c = 3.206 Å). When co-doping with Nb&F, the length of octahedron (4.136 Å) closely matches with pure SnO 2 (4.112 Å) in direction of perpendicular to the c-axis. The direct band gaps of 3.80 eV, 3.38 eV 3.63 eV, 3.23 eV, 3.06 eV have been obtained for pure, F, Nb, Nb&F and Nb&2F doped SnO 2 respectively, and the dispersed conduction band after doping does not significantly affect the electron effective mass of the conduction band minimum (CBM). A study of band alignment shows the clearly increasing valence band maximum (VBM) and the slightly decreasing CBM occur after doping. Analyses of the charge density difference and Bader charge suggest that Sn–O bond shows covalent characteristic, but the degree of ionization decreases in following order: Nb > Nb&F > Nb&2F > SnO 2 > F. In terms of optical properties after doping, the optical absorption side slightly red or blue shift, and the reflectivity in the visible spectrum is greatly low. [ABSTRACT FROM AUTHOR]

Ligand influence on the structural, electronic and optical properties of neutral Au 13 L clusters, where L = NH 3 , N (CH 3) 3 , PH 3 , P (CH 3) 3 , SCH 3 , SCH 2 Ph , SCH (CH 3) NH 2 , SCH (CH 3) Cl , SPh, SPhCH 3 , SPhCOOH and SeCH 3 , which has been investigated using density functional theory and its time-dependent approach. The analysis of the electronic stabilities reveals that the Au 13 SCH (CH 3) Cl and Au 13 NH 3 are the most stable among the other clusters of the thiolate or selenolate and of the phosphine or amine-ligated groups, respectively. The ligand effect on the optical absorption spectra of Au 13 L is relatively small, in which the main change is observed in the oscillator strength of the highest energy peak. [ABSTRACT FROM AUTHOR]

Since two-dimensional transition metal dichalcogenides (TMDs) and halide-based perovskites display superior optoelectronic properties, interfacing of TMDs and Janus materials with halide perovskites may improve the performance of photovoltaics and photodetectors. Using first-principles computations, this work thoroughly analyzes the electronic as well as optical properties of 2D CsPbX 3 /MYZ composites (X = Cl, Br, I; M = Mo, W; and YZ = S, Se). The findings demonstrate that the interaction of CsPbX 3 with the MYZ surface enables bandgap tuning, and interfacial electric field causing spatial charge separation, and results in small values of effective mass. In CsPbI 3 /MYZ and CsPbX 3 /MoS 2 hybrids, type-II band alignment ensures efficient carrier separation, thus lowering the recombination. While other heterostructures exhibited a type-I band alignment, suitable for long-lifetime photodetectors. The HSE06 bandgap for all heterostructures resides within desired range of 1.23–3 eV. The low tunnel barrier heights also favor high circuit voltages, suitable for photovoltaic applications. Next, remarkable absorption in hybrids promises their suitability for optoelectronics and radiation detection. Incorporation of water redox levels further validates their capability as photocatalysts driving overall water-splitting photocatalysis. [ABSTRACT FROM AUTHOR]

[Display omitted] • The electronic, optical, and drug delivery properties of GeSe nanoclusters are investigated using DFT calculations. • The GeSe nanoclusters are dynamically and energetically stable with positive formation energy and real vibrational frequencies. • The nanoclusters have abundant active sites on the edges and the surface that facilitate the adsorption of the drugs. • The anticancer drugs, adrucil and hydroxyurea, successfully adsorbed with adsorption energy ∼ -0.7 eV. • The suitable adsorption energy and the slight changes in the electronic structure render GeSe nanocluster potential as a drug delivery agent. For effective drug delivery, a drug carrier that is biocompatible, antitoxic, and appropriate for drug loading/release is required. Here, GeSe nanoclusters are investigated as potential drug delivery for anti-cancer drugs using density functional theory (DFT) calculations. They are dynamically and energetically stable with abundant active sites that facilitate binding with drugs. The anti-cancer drugs, adrucil and hydroxyurea, are successfully loaded on the nanoclusters with adsorption energy ∼ -0.7 eV. Interestingly, no chemical bonds were formed between the drug and the nanocluster highlighting the robust non-covalent interactions (NCI). These slight changes in the electronic properties after drug adsorption are confirmed by the partial density of states, natural bond orbital (NBO) and NCI analysis, and UV–vis spectra. This moderate adsorption without notable changes in the electronic structure facilitates the drug release at the infected tissue. Therefore, GeSe nanoclusters with appropriate electronic and drug adsorption/release properties represent a viable drug delivery agent. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two-dimensional Biphenylene nanoribbons are investigated using density functional theory calculations. • Formation energy and real vibrational frequencies confirm the stability of the nanoribbons. • In contrast to graphene, both the armchair and zigzag nanoribbons are nonmagnetic. • The UV–vis spectra show redshifts as size grows in both the armchair and zigzag directions. • The nanoribbons are promising candidates for oxygen evolution reaction with a low overpotential of 0.12 V. The electronic, optical, and catalytic properties of finite two-dimensional biphenylene nanoribbons are investigated using density functional theory calculations. The nanoribbons are energetically and dynamically stable as confirmed by the negative formation energy ∼ -7 eV and the real vibrational frequencies, respectively. Increasing the length of nanoribbons in the zigzag or armchair directions reduces the energy gap, with modest oscillations in the former case. In contrast to zigzag graphene nanoribbons, biphenylene ones have nonmagnetic spin ordering due to the passivation of the unpaired electrons at the zigzag edges by the 4C- rings connecting the benzene rings. The UV–vis spectra exhibit redshifts, with size increases in both the armchair and zigzag directions, which validate the electronic computations' results. Simulating the catalytic performance of oxygen evolution reaction shows remarkable performance with a low overpotential of 0.12 V. Thus, biphenylene nanoribbons with desirable electronic and catalytic properties are attractive anode materials for water-splitting cells. [ABSTRACT FROM AUTHOR]

Atomic doping is an effective method to adjust the electronic and optical properties of s-C 3 N 6. Herein, we studied the effects of atomic doping (S, Cl, Na and Mg) on the electronic, optical and redox properties of s-C 3 N 6 monolayer by first-principles calculations. We consider the substitutional doping of non-equivalent C or N atoms and interstitial doping at the hole position. The results show that atomic doping can effectively adjust the band gap of s-C 3 N 6 (2.59 eV) monolayer. Most notably, we found that S(N l)-s-C 3 N 6 is a quasi-direct band gap semiconductor with a band gap of 1.27 eV and the theoretical photovoltaic efficiency of S(N l)-s-C 3 N 6 is 31.84%, which indicates it has the potential to be used in thin-film solar cells. In addition, Cl6@s-C 3 N 6 meets the conditions of photocatalytic water splitting at pH = 7, and the Mg6@s-C 3 N 6 monolayer appears the reduction ability. Meanwhile, the atomic doped s-C 3 N 6 monolayer enhances the absorption intensity in the visible light range. The emergence of redox capacity and the enhancement of the absorption coefficient in carbon nitride monolayer via atomic doping reveals an exciting material platform for designing novel photovoltaic cells and nanoelectronics devices. [Display omitted] [ABSTRACT FROM AUTHOR]

The structural characteristics and qualities of two-dimensional (2D) materials can be engineered and improved for use in practical applications by applying strain. In this study, the structural, electronic, and optical properties of 2D Y 2 CCl 2 MXene are investigated by density functional theory (DFT). Our results show that the transition of bandgap indirect–direct occur under 8 % tensile strain which is related to the electronic states around the Fermi level. Moreover, the phonon spectra indicate that 2D Y 2 CCl 2 can continue to be stable with +8 % strain. The optical properties are investigated under the biaxial strain. The results of the absorption spectrum show that 2D Y 2 CCl 2 has good absorption in the near-infrared, visible, and UV regions. Hence, this material may be used in solar cell applications. Our results indicate that the tunable electronic and optical properties of semiconducting Y 2 CCl 2 MXene make them a promising candidate for the future applications of optoelectronic devices. [ABSTRACT FROM AUTHOR]

Heterostructures have attracted extensive attention due to their van der Waals interactions between layers. The photocatalysts of Two-dimensional (2D) heterostructure based on MoS _2 have tempted more and more attention because of their eminent photocatalytic performance, but they are still limited by the weak absorption of visible light and lesser conversion efficiency of solar-to-hydrogen. In this work, we exhaustively investigate the electronic, optical and the structural properties of 2D MoS _2 /TiO _2 heterostructures by using first-principles calculations. The result shows that both MoS _2 /TiO _2 (100) and MoS _2 /TiO _2 (001) heterostructures are stable interfaces and direct Z-scheme photocatalysts, which is favourable for the separation and migration of electron and hole pairs under the excitation of light. And what’s more, both the MoS _2 /TiO _2 (100) and MoS _2 /TiO _2 (001) heterostructures exhibit direct band gap at the Γ point, this is conductive to better electronic transition and absorption of light because of lower energy depletion than indirect band gap semiconductors. The relatively small band gap (1.08 eV of MoS _2 /TiO _2 (001) and 0.52 eV of MoS _2 /TiO _2 (100)) cause the entire visible light region can be covered by the light absorption spectrum. The result is that building heterostructures of TiO _2 with MoS _2 advances the absorption of light and hastens the separation and migration of electron and hole pairs, the activity of photocatalysis could be advanced by all of these. The results provide a basis of heterostructure photocatalysts based on monolayer MoS _2 and deep comprehension of their physical mechanism.

Density functional full-potential linearized augmented plane wave (FP-LAPW) investigations of structural, mechanical and optoelectronic features of cubic BeSxSe1−x, BeSxTe1−x and BeSexTe1−x ternary alloys are performed. Nonlinear decrease in lattice constant ( a 0 ), but increase in bulk modulus ( B 0 ) and each elastic constant ( C 11 , C 12 and C 44 ) occurs with increasing dopant chalcogen concentration x in each system. In each specimen, elastic anisotropy, brittleness and dominancy of covalent bonding are observed. Each binary compound and ternary alloy at x = 0.25 and 0.75 is a direct (Γ–Γ) bandgap semiconductor, and ternary alloy at x = 0.50 is an indirect (X–Γ) bandgap ( E g ) semiconductor. Nonlinear increase in bandgap ( E g ) with increase in x is observed in each alloy system. Chalcogen-p → Be-3s, 2p optical excitations contribute intense peaks in each spectra of the imaginary part of the dielectric function ε 2 (ω) . The trend of variation of zero-frequency limit in each real dielectric function ε 1 (ω) , refractive index n (ω) and normal incidence reflectivity R (ω) spectra and critical point in each of the imaginary dielectric function ε 2 (ω) , extinction coefficient k (ω) , optical conductivity σ (ω) and optical absorption α (ω) spectra with x is opposite and similar, respectively, to the trend of variation of bandgap ( E g ) with x. [ABSTRACT FROM AUTHOR]

Coumarin derivatives have gathered major attention largely due to their versatile utility in a wide range of applications. In this framework, we report a comparative computational investigation on the optoelectronic properties of 3-phenylcoumarin and 3-heteroarylcoumarin derivatives established as enzyme inhibitors. Specifically, we concentrate on the variation in the optoelectronic characteristics for the hydroxyl group substitutions within the coumarin moiety. In order to realize our aims, all-electron density functional theory and time dependent density functional theory calculations were performed with a localized Gaussian basis-set matched with a hybrid exchange–correlation functionals. Molecular properties such as highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies, vertical ionization (IEV) and electron affinity energies, absorption spectra, quasi-particle gap, and exciton binding energy values are examined. Furthermore, the influence of solvent on the optical properties of the molecules is considered. We found a good agreement between the experimental (8.72 eV) and calculated (8.71 eV) IEV energy values for coumarin. The computed exciton binding energy of the investigated molecules indicated their potential optoelectronics application. [ABSTRACT FROM AUTHOR]

C 3 F 7 CN((CF 3) 2 CFCN) is a potential environmentally friendly insulating gas to alternative SF 6. Finding an effective way to monitor C 3 F 7 CN gas decomposition products is necessary to ensure the stable operation of power equipment. The adsorption behaviors of typical decomposition products (CF 4 and CF 3 CN) on pristine boron nitride nanotubes(BNNT) and C-doped boron nitride nanotubes(C-BNNT) were investigated. The adsorption energy of CF 4 and CF 3 CN on pristine BNNT is small, and the interaction distance between molecules is large, which indicates that pristine BNNT and gas molecules form physical adsorption through weak van der Waals forces. Then, we studied the adsorption behaviors between C-doped BNNT and gas molecules. The adsorption of CF 4 on C-doped BNNT has a few effect on the band gap of C B -BNNT. For CF 3 CN molecules, the adsorption of F atoms on the C-doped BNNT is physical adsorption, while the N atom in the -CN group forms chemical adsorption at the C N and C B sites, with higher charge transfer amount. After adsorption -CN group, and the 2p orbital of N atom and the 2p orbital of doped C atom dominate at the Fermi level, which changes band gap of C-doped BNNT. Meanwhile, adsorption behaviors weaken the absorption capacity of C-BNNT for infrared light and reduce its reflectivity to ultraviolet light. Tube diameter has a significant effect on the adsorption of N atom of CF 3 CN on C-BNNTs, the band gap and optical properties changes with the diameter increases. These changes of electronic and optical properties indicated that C-doped BNNT can be used as a potential material for detecting CF 3 CN. • The adsorption of CF 4 and CF 3 CN on pristine BNNT was not obvious. • The adsorption performance of C-doped BNNT is better, especially for -CN group. • When the gas is adsorbed on C-BNNT, the absorption of infrared light decreases. • The band gap and optical properties changes with increasing the diameter of C-BNNT. [ABSTRACT FROM AUTHOR]

Using the first principle calculations, the structural, electronic and optical properties of the monolayer graphene-like MoX2 sheet are calculated. Our results show that the chalcogenide atoms in the stability and the lattice parameters of the MoX2 sheet have a key role, although it is known that the electronic properties are more dependent on the metal atoms in these sheets. Our data also confirm semiconductor behavior of the MoX2 monolayers with direct band gap for S, Se and Te chalcogenides. Compared with the bulk compounds, they have similar structural properties but represent unique electronic and optical properties that can be used in nano-devices, nano-electronics and so on. In this work, the investigation of the chalcogenide atoms role in modifying the optical properties of these single-layer sheets, such as absorption and refraction coefficients, is carried out; the dielectric constant plays an important role. We also try to study the possibility of using these compounds on the solar energy industries and optical devices. [ABSTRACT FROM AUTHOR]

In this study, the structural models and electronic and optical properties of the ZnTe/InP heterojunction (HJT) were systematically investigated by first-principles calculation based on density functional theory. The results show that the structural stability of model II is better than the other two stacking configurations, and the binding energy is the lowest when the interlayer spacing is 2.4 Å (d2.4-ZnTe/InP). The electronic structure of the ZnTe/InP HJT exhibits characteristics of type II band alignment. Additionally, it was found that the bandgap of the ZnTe/InP HJT can be readily tuned by changing the interlayer spacing. The charge density difference shows that covalent bonds are formed between the layers of the ZnTe/InP HJT, which can enhance the interfacial bonding strength of the heterostructure. The strongest peak of the absorption coefficient of the ZnTe/InP HJT appears in the ultraviolet zone, indicating that it has excellent ultraviolet absorption capacity. Overall, the relevant calculation results can provide a useful theoretical reference for the practical application of ZnTe/InP HJTs in nano-electronic devices. [ABSTRACT FROM AUTHOR]

The optoelectronic properties of ZnS nanowires (NWs) and ZnS—Si core shell nanowires (CSNWs) oriented along different directions has been investigated using first principles calculations. Both NWs and CSNWs exhibit semiconductor characteristics in [100] and [111] directions while [110] oriented NWs and CSNWs exhibit metallic characteristics. The semiconductor characteristics of the ZnS NWs and ZnS—Si CSNWs in [100] and [111] directions have been confirmed from the electronic and optical energy gaps. We observed strong optical absorption in [110] directional ZnS—Si CSNWs throughout the spectrum from visible to UV region which represents significance to the optoelectronic and energy harvesting devices. Furthermore, the parallel and perpendicular parts of the optical absorption of ZnS—Si CSNWs show good improvement as compared to ZnS NWs. The refractive index and reflectivity spectra of ZnS—Si CSNWs also offered considerably upgraded values than ZnS NWs. Our predicated optical static dielectric constant ε 1 (0) and static refractive index n (0) values are also much better than the previously reported one. The strong optical absorption in [110] directional ZnS—Si core shell nanowires from visible to UV region represents significance to the optoelectronic and energy harvesting devices. Display Omitted • ZnS NWs and ZnS/Si CSNWs are semiconductors in [100] and [111] directions and are metals in [110] direction • Strong optical absorption in ZnS NWs and ZnS—Si CSNWs growing along [110] direction are observed • The refractive index and reflectivity spectra of ZnS/Si CSNWs also offered upgraded values than ZnS NWs • ZnS/Si CSNWs growing along [110] direction are good condidate for the optoelectronic devices [ABSTRACT FROM AUTHOR]

α-Graphyne nanotubes as quasi-one-dimensional structures could have interesting electronic and optical properties in comparison to graphene. In this work, we have calculated electronic band structure, density of states and optical absorption spectrum of some single-wall zigzag α-graphyne nanotubes by using a simple tight-binding method in a reduced lattice. The results show that two-thirds of nanotubes have semi-conductive behavior accompanied with an oscillatory decreasing band gap, while the rest presented metallic characteristics. The outcome reveals the optical gap fluctuates per different incremental nanotube diameters; in addition, the highest amount of optical absorption occurs when emission energies exceed 4 eV. [ABSTRACT FROM AUTHOR]

Abstract Perovskite structure CH 3 NH 3 PbI 3 has been receiving considerable attention due to its promising applications in many optoelectronic fields such as photovoltaics, photodiodes, sensors and catalysts. As studying the structural and optoelectronic properties of CH 3 NH 3 PbI 3 under pressure can be beneficial to explore unusual lattice structures, new chemical and physical properties of this material, first-principles calculations based on density functional theory have been performed in this work to investigate the electronic and optical properties of CH 3 NH 3 PbI 3 under pressure. Moreover, the standard deviation σ of Pb‒I bonds in [PbI 6 ]4- octahedrons were used for the first time to characterize the distortion degree of octahedrons. It is found that both the decrease of Pb‒I bond lengths and the distortion of [PbI 6 ]4- octahedrons in CH 3 NH 3 PbI 3 under pressure have significant effects on the band gap changes of tetragonal, cubic and orthorhombic structures of CH 3 NH 3 PbI 3. The interactions between Pb and I atoms in three structures have mixed covalent and ionic bonding characters, the covalent character of Pb‒I bonds is quite weak in comparison with the classical C‒N covalent bonds. The optical properties including the complex dielectric function, refractive index, extinction coefficient, reflectivity and absorption coefficient for three CH 3 NH 3 PbI 3 structures under pressure were also determined. [ABSTRACT FROM AUTHOR]

We report the results of first-principles calculations regarding the structural parameters, elastic moduli, electronic structure and optical properties of the ternary rhombohedral layered compounds, KLaSe2 and RbLaSe2. These calculations were performed by employing the pseudo-potential plane-wave (PP-PW) method. Although the calculated structural parameters (a, c, V, c/a, bond-length d) using different exchange and correlation approximations are found in nice harmony with the available experimental data, the best agreement is obtained with the GGA-PW91 functional. The effect of the K–Rb substitution is noted very clearly on the degree of ionic bonding of the A–Se bond (A = K, Rb). The electronic band structure and the density of states (DoS) plots reveal the semiconducting characteristics of both compounds with an indirect bandgap energy, E g of about 2 eV. The mechanical stability of the ALaSe2 compounds is investigated for the first time by calculating the single-crystal elastic constants C i j using the stress-strain approach. In order to understand the linear optical properties of the studied systems, frequency-dependent polarized optical functions were computed for an energy range from 0.0 eV to 18 eV. Our calculated optical spectra reveal the isotropic nature of the optical properties of the ALaSe2 compounds. [ABSTRACT FROM AUTHOR]

In this paper, a systematic investigation of electronic structure and optical properties of quaternary chalcopyrite semiconductors Cu 2 ZnGeS 4 and Cu 2 ZnGeSe 4 in stannite and kesterite structures using the full-potential linearized augmented plane wave method are presented. The electronic structures and related properties of the crystals are studied with density functional theory using modified Becke – Johnson (mBJ) potential. The computed bands and density of states are found to be in good agreement with the available experimental and theoretical results. Important optical properties such as, dielectric functions, absorption spectra, refractivity and reflectivity of the crystals have also been investigated using the mBJ exchange potential. The imaginary parts of dielectric tensor are analyzed in terms of interband transitions. The band gap energies of stannite CuZnGeS 4 (CuZnGeSe 4) and kesterite CuZnGeS 4 (CuZnGeSe 4) compounds are obtained as 1.23 (0.74) eV and 1.52 (1.08) eV, respectively. Present band gap energies and optical parameters show feasibility of the studied materials in photovoltaic and other optoelectronic devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • Finite nanotubes with controllable electronic properties and abundant active sites were constructed from methylene-bridged cycloparaphenyleneas. • The electronic, optical, and catalytic properties are investigated using density functional theory. • The energy gap significantly decreases by increasing the nanotube length due to the evolution of localized states at C-atoms of the pentagonal rings. • The localized states contain interactive electrons that are active sites for catalytic activities. • The UV–Vis spectra show redshifts by increasing the nanotube length confirming the decrease in the energy gap. • With the remarkably low OER overpotential and the abundant active sites, the considered nanotubes are then exceptional catalysts for OER. Nanotubes constructed from methylene-bridged cycloparaphenyleneas (MCPPs) are investigated using density functional theory. The dynamical stability is indicated by the real vibrational frequencies of the infrared spectra. MCPPs are semiconductors with an energy gap of ∼ 2.9 eV that significantly decreases in the finite nanotubes. This decrease is a result of the interactive molecular orbitals that are localized at the pentagonal rings linking MCPPs. The UV–vis spectra show that transitions from the highest occupied and neighbor orbitals to the lowest unoccupied orbital dominate the primary absorption peaks. Oxygen evolution reaction shows that all the reaction intermediates, HO, O, and HOO are adsorbed by the pentagonal active sites. The considered nanotubes show good catalytic performance but the best performance is observed in the wider nanotubes with an overpotential of 0.10 V. This remarkably low overpotential in addition to the abundant active sites makes finite nanotubes from MCPPs exceptional catalysts for oxygen evolution. [ABSTRACT FROM AUTHOR]

The non-metallic doped g-C 3 N 4 /MoS 2 (X/g-C 3 N 4 /MoS 2 , X = O, F, Si, P, S, and Cl) heterojunctions are designed by the First-principles. The electronic, optical properties, and the effect of the electric field on the band structure of the X/g-C 3 N 4 /MoS 2 heterojunctions are investigated. The O/g-C 3 N 4 /MoS 2 heterojunction is a semiconductor (1.340 eV, Type-II), and the F, Si, P, S, and Cl/g-C 3 N 4 /MoS 2 heterojunctions exhibit metallic properties. The built-in electric fields generated at the interface enhance the separation efficiency of the photo-generated electron hole pair. Further, the band structures are controllable by the electric field, especially, the band structure of the O/g-C 3 N 4 /MoS 2 heterojunction changes from semiconductor to metallic properties (0.4 V Å−1), while that of the S/g-C 3 N 4 /MoS 2 heterojunction changes from metallic to semiconductor properties (−0.4 V Å−1 and −0.2 V Å−1). In the meantime, the visible light absorption coefficient is enhanced, especially, the Si/g-C 3 N 4 /MoS 2 heterojunction has an absorption peak of 1.188 × 105 cm−1 at 625.8 nm. Furthermore, the O/g-C 3 N 4 /MoS 2 heterojunction can occur photocatalytic water decomposition under acidic conditions. [ABSTRACT FROM AUTHOR]

[Display omitted] • DFT simulations were used to calculate the electronic and optical properties of four interfaces on Graphene monolayers. • The bandgap values were 0.02 eV, 0.07 eV, 0.2 eV and 1.08 eV for SnSe-Gr, SnSe 2 -Gr, Gr-SnSe-Gr and Gr-SnSe 2 -Gr, respectively. • Mobility values were 126 × 103 cm2V−1 s−1 for a two layers SnSe and 69 × 103 cm2V−1 s−1 for three layers SnSe 2. • Absorption spectrum indicated two low frequency peaks at 60 THz and 48 THz for Gr-SnSe-Gr and Gr-SnSe 2 -Gr heterostructures. • Narrow band gap and negative dielectric constant of SnSe on Gr-SnSe-Gr resulted from plasmonic state in 24–169 THz range. Density functional theory (DFT) calculations have been used to investigate physical–chemical sensing of various proposed interfaces as SnSe@Graphene, SnSe 2 @Graphene, Graphene@SnSe@Graphene, and Graphene@SnSe 2 @Graphene, where dispersion corrections have been included to taken into account the vdW interactions between the layers. Initially, we predicted the electronic structures, mobility and carrier concentrations (cc) of SnSe and SnSe 2 structures. Using different methodology, the outcomes have confirmed the semiconductor properties of SnSe and SnSe 2 with indirect bandgap of 1.20 eV and 0.94 eV calculated by Generalized Gradient Approximation (GGA) and MetaGGA (MGGA) adopted with Perdew-Burke-Ernzerhof (PBE) functional, while hybrid Heyd-Scuseria-Ernzerhof (HSE) hybrid functional overestimated the experimental observations for both materials. Room temperature high mobility and cc have predicted by 126 × 103 cm2V−1 s−1 with cc of 1.3 × 1013 cm3 for a two layers SnSe and 69 × 103 cm2V−1 s−1 with cc of 4.2 × 1018 cm3 for three layers SnSe 2. Optical absorption spectrum revealed that the presence of two peaks at 60 THz and 48 THz with the intensity of 89879 cm−1 and 34504 cm−1 for interfaces including two layers of graphene. More interestingly, dielectric constant calculations showed that the transfer of carriers between graphene layers and SnSe in Graphene@SnSe@Graphene interface with absorption peak shifted to 24 THz along the in-plane direction and negative dielectric constants in the range of 24–169 THz, showing the effect of light-trapping through plasmonic. [ABSTRACT FROM AUTHOR]

• Nanobelts and nanoribbons based on hexagonal graphene quantum dots were constructed. • The nanobelts are characterized by significantly low energy gap compared to the nanoribbons or the nanodots. • The constructed nanobetls can adsorb volatile organic compounds with moderate adsorption energy and charge transfer. • The interactive electronic states and the moderate adsorption energy make these systems promising candidates for sensing and catalytic applications. New nanobelts and nanoribbons are built from zigzag-hexagonal graphene quantum dots. Their stability, electronic, optical, and sensing properties are studied using density functional theory calculations. The infrared spectra's real vibrational frequencies and positive binding energy prove the stability of the constructed structures. The thermal stability at 600 K is also confirmed by molecular dynamics simulations. The nanobelts have a significantly low energy gap compared to the planer single quantum dots or the extended nanoribbons based on these nanodots. This is a result of the wrapping of the graphene nanodots which raises the π-overlapping between adjacent rings that decreases the energy gap. Interactive electronic states localized at the zigzag edges characterize both nanobelts and nanoribbons. Thus these systems are promising candidates for sensing and catalytic applications. Their sensing capability is tested by studying the adsorption of selected volatile organic compounds such as chloromethane and trichloroethylene. The findings indicate that these gases are effectively adsorbed with moderate adsorption energy and charge transfer, opening the door toward gas sensor applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • In-depth investigation of super-zethrene (SZ) and derivatives covering structural, electronic, optical, and electrical properties. • Unveiling planarity of SZ and non-planar conformations of derivatives, offering insights into their intriguing structural characteristics. • Revealing unique electronic trends through energy gap analysis and spin-up characteristics, elucidating their electronic behavior. • Quantifying stability, quantum parameters, and electrical attributes, showcasing their promising potential for diverse electronic and optoelectronic applications. This study investigates the optimized molecular structures, stability, electronic, optical, and transport properties of super-zethrene (SZ) chains connected by C-atoms. Through computational analysis, the research uncovers intriguing structural features, such as SZ's planarity compared to non-planar conformations in derivatives. Binding energy calculations reveal increasing stability with the increase of the connected SZ, with 3SZ-3C emerging as the most stable configuration. Spin-polarized calculations show that SZ has antiferromagnetic spin ordering that is kept unchanged after connection with an even number of C-atoms. In some chains connected with an odd number of C-atoms, the chain becomes ferromagnetic with spin-triplet multiplicity. Spin-up electronic characteristics exhibit consistent trends, except for 2SZ-3C, with energy gap reductions tied to higher n, notably in 3SZ-2C and 2SZ-2C. Quantum stability parameters and electrical conductivity evaluations emphasize desirable electronic attributes, suggesting potential applications. Molecular electrostatic potential (MEP) studies pinpoint reactive sites, crucial for understanding chemical behavior. UV–Vis absorption spectra demonstrate distinctive optical transitions influenced by n and m variations. Current/voltage profiles showcase unique electrical trends, highlighting saturation points linked to the number of connecting carbon atoms. Collectively, this study provides a comprehensive exploration of laterally connected SZ chains, revealing their structural, electronic, optical, magnetic, and electrical properties, offering prospects for diverse electronic and optoelectronic applications. [ABSTRACT FROM AUTHOR]

The structural, electronic, and optical properties of inorganic CsPb(I1−xBrx)3 compounds were investigated using the full-potential linear augmented-plane wave (FP-LAPW) scheme with a generalized gradient approximation (GGA). Perdew–Burke–Ernzerhof generalized gradient approximation (PBE-GGA) and modified Becke–Johnson GGA (mBJ-GGA) potentials were used to study the electronic and optical properties. The band gaps calculated using the mBJ-GGA method gave the best agreement with experimentally reported values. CsPb(I1−xBrx)3 compounds were wide and direct band gap semiconductors, with a band gap located at the M point. The spectral weight (SW) approach was used to unfold the band structure. By substituting iodide with bromide, an increase in the band gap energy (Eg) values of 0.30 and 0.55 eV, using PBE-GGA and mBJ-GGA potentials, respectively, was observed, whereas the optical property parameters, which were also investigated, demonstrated the reverse effect. The high absorption spectra in the ultraviolet−visible energy range demonstrated that CsPb(I1−xBrx)3 perovskite could be used in optical and optoelectronic devices by partly replacing iodide with bromide.

Abstract The electronic and optical properties of armchair germanene nanoribbons (AGeNRs) are studied using the first principles calculations. The band structure, band-gap size, projected density of states (PDOS), and dielectric function of AGeNRs are calculated. Moreover, the variation of these parameters as a function of various ribbon widths is investigated. By increasing the width of ribbons the band-gap size of pristine AGeNRs is decreased according to three different trends. Based on these trends, it is extracted that the AGeNRs can be divided into three categories named as n = 3P, n = 3P+1, n = 3P+2, here n is the number of germanium atoms in the width and P is an integer. Moreover, all these categories are direct band-gap materials and the order of band-gap size is changed as: E G (3P+2) < E G (3P) < E G (3P+1). Due to the direct band-gap size, it can be extracted that all of AGeNR categories are proper for optical applications. Based on the simulation results of this work, it is demonstrated that the AGeNRs are appropriate for optical devices in the range of infrared applications. In addition, the effect of uniaxial tensile and compressive strain on the band-gap size and the dielectric function of AGeNRs is investigated and it is shown that the electronic and optical properties of AGeNRs can be tuned by strain in a wide range. Highlights • We study the electronic and optical properties of AGeNRs by density functional theory. • Band-gap size of AGeNRs is changed by the width of ribbons. • Imaginary part of the dielectric function is calculated according to width variation. • The electronic and optical properties of AGeNRs can be tuned by uniaxial tensile and compressive strain in a wide range. • AGeNRs are appropriate for optical devices in the range of infrared applications. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract In this work, we report theoretical and experimental studies on the structural, electronic and optical properties of wurtzite Zn 1−x Cd x O alloys. The theoretical investigations were conducted using the density functional theory (DFT) as implemented in the Wien2k package which is based on the full potential linearized augmented plane wave (FPLAPW). The modified exchange potential proposed by Becke-Johson (mBJ) with local gradient generalized approximation (GGA) was used in this study. The lattice parameters, electronic structure and optical properties were studied in details for the composition x of cadmium 0, 0.16, 0.25, and 0.33. Experimentally, Zn 1−x Cd x O alloys were grown by the sol–gel spin coating method with different cadmium concentrations specifically x = 0, 0.10, 0.20, and 0.30. The obtained experimental results were systematically analyzed and compared with the DFT calculations. From the theoretical findings, it is noticed that the structural and electronic properties of Zn 1−x Cd x O are strongly affected by the Cd doping amount. The lattice parameters increase and the band gaps decrease with the x fraction of cadmium showing a quantitative agreement with the experimental results. Moreover, the investigation of the total and partial density of the Zn 1−x Cd x O alloy for the different bands reveals that the optical transition between O-2p states in the top of valence band and Zn-4s states in the bottom of the conduction band is shifted to lower energy range as the Cd concentration increases. In addition, the dielectric function, the absorption coefficient, and the refractive index and discussed for the different cadmium composition. Combining both theoretical calculations on Zn 1−x Cd x O alloys with the obtained experimental results provides better understanding of the physical properties dependence on the composition and would help to engineer such alloys for high performance optoelectronic and nonlinear optical devices. [ABSTRACT FROM AUTHOR]

Chemical functionalization of H-graphene cluster by an epoxy group has been deemed to be an effective way to tune the electronic structure of H-graphene and open its band gap. It is important to understand the atomic structure of H-graphene oxide in order to utilize its fundamental properties and explore its potential applications. Therefore, it is essential to know the arrangement of oxygen-containing functional groups in H-graphene oxide. A computational study using DFTbased reactivity descriptors to identify favorable sites of epoxy groups on the H-graphene surface was performed in this work. Structural, electronic and optical properties of epoxy groups in various positions of the H-graphene surface were compared. All calculations were performed using DMol3 code in Materials Studio. Optical properties of epoxy groups show that the electron transmissions from HOMO to LUMO, which are related to the energy gap, have the highest wavelength and the least amount of oscillator power in all structures. The highest wavelength, which occurs in the transmission H→L (1512 nm), is related to structure 10. This is consistent with the results of the energy gap and global softness. The energy of interactions is negative in all structures, which indicates that the interaction between the oxygen atom and H-graphene, which results in the formation of H-graphene epoxy, is exothermic. The number of electron occupancy states in the energy levels between HOMO and LUMO has changed for oxygen-absorbed H-graphene, which indicates the effect of oxygen on the H-graphene surface. [ABSTRACT FROM AUTHOR]

Abstract Janus Ga 2 STe, Ga 2 STe, and Ga 2 SeTe monolayers have been designed composed of GaS, GaSe, and GaTe monolayers and study their electronic and optical properties using the density functional theory. Interestingly, our results revealed that the Ga 2 STe and Ga 2 SeTe have desirable direct band gaps of 0.90 and 1.21 eV, respectively, while Ga 2 STe has an indirect gap of 2.02 eV, all of the energy bandgaps are smaller than those of the perfect monolayers. The optical absorption confirms a strong absorption of the light in the range between 3 and 21 eV. More importantly, the optical absorption of Janus structures begins in the visible region with absorption coefficients larger than 104 cm−1. Combining the optical and electronic properties, Ga 2 STe, Ga 2 STe, and Ga 2 SeTe monolayers have a great possibility to be used as ultraviolet detectors and photovoltaic absorbers applications. Consequently, the present work offers significant guidelines for the design of optoelectronic devices that made of layered Janus structures and provides useful guidance for further expanding the practical application range of these materials. Graphical abstract Image 1 Highlights • Janus Ga 2 SSe, Ga 2 STe, and Ga 2 SeTe monolayers have desirable direct band gaps of 0.90 and 1.21 eV, respectively. • Janus Ga 2 SSe, Ga 2 STe, and Ga 2 SeTe monolayers have a variety of extraordinary optical properties. • The optical absorption of Janus structures begins in the visible region with absorption coefficients larger than 104 cm−1. • The optical properties of Ga 2 SSe, Ga 2 STe and Ga 2 SeTe monolayers located in UV range. • Janus monolayers can be used as a promising material in the ultraviolet detectors and optoelectronic applications. [ABSTRACT FROM AUTHOR]

Abstract In this work, structural, electronic and optical properties of In x Ga 1-x N are calculated by using full potential linearized augmented plane wave method. The calculated lattice parameters are found to be increased with the increase in In concentration and slightly deviating from the Vegard’s law. Band gaps are calculated by generalized gradient approximation (GGA) and modified Beck-Johnson (mBJ) GGA. The calculated band gaps are found to be decreased with the increase in In Concentration. The mBJ-GGA band gaps are very close to experimental values. Optical characteristics such as refractive index and dielectric constants are also calculated. The calculated parameters suggested that the materials are suitable for optoelectronics applications. [ABSTRACT FROM AUTHOR]