Calculated Band Gap Research Articles

ENHANCING SOLAR CELL EFFICIENCY: A COMPREHENSIVE STUDY ON THE OPTO-ELECTRICAL PROPERTIES OF CUINALSE<sub>2</sub> THIN FILMS AS AN ABSORBER LAYER

CIAS (CuInAlSe2) thin films were prepared by 1-step electrodeposition on ITO coated glass substrate by varying deposition potential to obtain low cost, uniform and compact crystallinity at room temperature. The 200ml solution has been prepared and operated at 0.55V to 0.95V deposition potentials. CIAS solution has been prepared at different molarity ratios varying from 0.1M to 1.0M solution and optimum results obtained at 0.5M molar solution. The results obtained from cyclic voltammetry reveals that quaternary compound having different reduction potential can be deposited in potential range 0.5V to 0.95V. XRD technique were used to study the structural, morphological properties of thin films that shows the strong evident of its crystalline nature having tetragonal pure phase with preferred orientation at (400) plane. The result showed that single phase having good stoichiometry can be produced in this potential range. The optical properties studied by ellipsometry technique revealed that the films are highly absorbing in visible and visible-infrared region by increasing deposition potential. The band gap calculation form absorption spectra were maintained at 1.11 to 1.32 eV which was excellent for good absorbing solar materials. Hall effect application van der pauw method used for electrical properties which show promising results for production of electricity by solar cells. The variation of deposition potential offers very effective change in band gap. Structural, morphological, electrical and optical properties were carried out to establish the suitability of thin films for solar cells fabrication.

A computational exploration of structural, electronic, and optical properties of Hf- substituted CaZr1-x HfxS3 (x = 0.25, 0.50, and 0.75) for photovoltaic applications

Abstract This study investigates the structural, electronic, and optical properties of Hf-substituted CaZrS₃ (CaZr_(1-x) Hf_x S_3, where x =0.25,0.50, and 0.75) for photovoltaic applications. Using first-principles calculations within the Quantum Espresso framework, we explore the effects of Hf incorporation on the orthorhombic crystal structure (Pnma space group). The study reveals that Hf substitution significantly influences the material’s properties, including lattice parameters, band gap, and optical absorption. The calculated band gaps for Hf-substituted CaZrS₃ are smaller than the experimental value for unsubstituted CaZrS₃, indicating enhanced suitability for photovoltaic applications. Moreover, Hf substitution improves the thermal, mechanical, and chemical stability of the material. The results suggest that Hf-substituted CaZrS₃ is a promising candidate for high-efficiency, stable, and environmentally friendly photovoltaic devices.

Designing Double Perovskites with Organic Dications for Enhancing Stability and Photoelectrical Performance.

Recently, the research on developing lead-free double-B-cation halide perovskites has attracted attention. However, Cs2InBiCl6, the most promising one, was shown to be thermodynamically unstable. To improve the stability, organic dication DiMA2+ (i. e., (CH2NH3)+(CH2)3(CH2NH3)+) is introduced to design the new double perovskite DiMAInBiX6 (X=Cl, Br, and I) based on Cs2InBiX6 by replacing two Cs+ with a DiMA2+. Density functional theory calculations were performed to study the geometric and photoelectric properties of the newly designed materials. Unlike Cs2InBiX6, both DiMAInBiCl6 and DiMAInBiBr6 can exist stably against decompositions, indicating that the replacement of Cs+ by DiMA2+ will improve stability of double perovskites due to the staple effect. In addition, the replacement causes an increase in the band gaps of DiMAInBiX6. Particularly, the calculated band gap of DiMAInBiBr6 (1.31 eV) is close to the optimal value of single junction perovskite solar cell (PSC). Under ideal conditions, the PSC model constructed with DiMAInBiBr6 performs the best in theoretical simulation. This work proposes DiMAInBiBr6 as a promising light absorber of PSC, which has high stability and photoelectric performance. It also suggests that the replacement of Cs+ by DiMA2+ may serve as a rational and practical way to design new organic-inorganic hybrid double perovskites.

Chiral Bimetallic Cuprous-Lead Hybrid Iodide Single Crystals toward Occurrence of Second Harmonic Generation.

Hybrid bimetallic halides with two different optical activities have exhibited excellent optical properties, which demonstrates great potential in the optoelectronic fields. To develop hybrid cuprous-lead bimetallic halides with unique non-centrosymmetric structures, we introduced the chiral cations R/S-2-C5H14N22+ (C5H14N22+ = methylpiperazinium) into inorganic frameworks containing two different heterometallic cuprous and lead cations, respectively, and successfully obtained the novel chiral hybrid bimetallic halides of (R/S-2-C5H14N2)3Cu2Pb2I12 single crystals by the hydrothermal method. Bimetallic anionic [Cu2Pb2I12]6- framework structures were constructed from two different [PbI6]4- and two different [CuI4]3- twisted polyhedra, and band gap calculations were demonstrated. Most importantly, chiral crystal structures of (R/S-2-C5H14N2)3Cu2Pb2I12 were confirmed by circular dichroism (CD), and their anisotropy factor (gCD) values were -5.98 × 10-5 and +5.79 × 10-5, respectively. Besides, significant second harmonic generation of (R/S-2-C5H14N2)3Cu2Pb2I12 single crystals was also exhibited through the coupling of chiral organic cations and inorganic anionic [Cu2Pb2I12]6- frameworks. This work not only provides guidance for understanding the structure-property relationship of novel chiral hybrid bimetallic halides, but also extends the further optoelectronic applications of these hybrid halide systems.

Influence of Capping Agents for Controlling Structural and Optical Properties of Copper Chalcogenide (CuS) Nanoparticles

Abstract Copper based chalcogenides have attracted considerable attention in recent years due to their exclusive properties that are tunable by the structure, stoichiometry and composition. Among the categories of chalcogenides, copper sulfide (CuS) has been the subject of extensive research as it exists in various stable phases. The present work emphasizes on the impact of capping agents: aloe vera and polyvinyl alcohol (PVA) on structural and optical properties of CuS (covellite) nanoparticles. Structural characterization of the as-synthesized CuS/PVA and CuS/Aloe vera nanoparticles is done using X-ray diffraction (XRD) while their morphology is examined with Field Emission Scanning Electron Microscopy (FESEM). The chemical stoichiometry of synthesized CuS nanoparticles is performed using Energy Dispersive X-ray Spectroscopy (EDS). UV-Vis absorption and photoluminescence (PL) spectroscopy are employed to study the optical properties. The XRD shows the presence of diffraction peaks for CuS. The average crystallite size calculated for the prepared CuS/PVA and CuS/Aloe vera nanoparticles using Debye Scherrer’s equation are 4.59 nm and 3.58 nm respectively. Band gap calculation from Tauc’s plot showed the corresponding direct optical band gap of the synthesized CuS/PVA and CuS/Aloe vera nanoparticles to be 2.87 eV and 3.75 eV, indicating blue-shift due to quantum confinement. Photoluminescence spectra of as-synthesized samples indicated strong emission at 467 nm for both the samples: CuS/PVA and CuS/Aloe vera. Optical properties of the as-synthesized nanoparticles showed that they are promising materials for optoelectronic devices. Aloe vera, the environment friendly and non-toxic agent is found to be a suitable “green” passivator in stabilizing CuS nanoparticles.

Tecoma stans intermediated green synthesis of copper oxide nanoparticles, its characterization, paracetamol degradation and biological activities

The main objective of the present research work is to green synthesize copper oxide nanoparticles (CuO NPs) and to study its potential against various enmities to safeguard our environment and health. Based on this approach, preparation of CuO NPs was accomplished using four different volumes (10, 25, 40, and 50 mL of leaves extract) of Tecoma stansleaves extract. Moreover, all the synthesized CuO NPs were characterized using XRD, UV–visible, FTIR, and SEM with EDS analysis. From the XRD pattern, the structures of all the synthesized CuO NPs were found to be monoclinic in phase. According to the UV–visible studies, the calculated band gap energy values for all the prepared CuO NPs were higher compared to bulk CuO, which was 1.2 eV. Further, the FTIR results showed the presence of CuO bond and SEM with EDS analysis revealed the surface morphology of CuO NPs andthe presence of elements showing the purity of synthesized CuO NPs, respectively. The optimized condition for the preparation of CuO NPs were 50 mL of leaves extract mixed with 50 mL of double distilled water (CuO4 NPs) showed a spheroidal morphology as evident from the HRTEM images. XPS analysis used to find the oxidation state of detected elements especially for copper and oxygen. The predicted BET and Langmuir surface area of CuO4 NPs were calculated to be 40.305 m2/g and 5074.12 m2/g respectively. Photocatalytic degradation of paracetamol (PCM) using CuO4 NPs was investigated, and the effect of parameters such as pH, initial concentration of PCM solution, and catalyst dosage were studied under UV light irradiation. The highest removal of 95.15 % had been achieved at 120 min under optimized reaction conditions. Additionally, CuO4 NPs also exhibited exemplary antibacterial activity against bacillus subtilis bacteria with a zone of inhibition of 26 mm. Further, in vitro cytotoxic behaviour of CuO4 NPs was estimated using A549 cancer cells by MTT assay. Thus, the green synthesis of CuO NPs using Tecoma stans leaves extract has the capacity to participate in photocatalytic and biological activities.

Structural, electronic, optical, magnetic, and mechanical properties of SmMnO3 perovskite with europium and yttrium doping: A first-principles study

This paper explores the impact of europium (Eu) and yttrium (Y) doping on the electronic, magnetic, optical, elastic, and structural properties of SmMnO3 perovskites using the Quantum ESPRESSO code. The cohesive energy and tolerance factor calculations revealed that the perovskite can maintain structural stability up to 25% doping of Eu and Y. Bandgap calculations suggest that when Eu and Y are doped, the energy bandgap of pure SmMnO3 decreases significantly from 2.72 to 0.47 and from 2.72 to 0.76 eV, respectively. Doped SmMnO3 exhibits a UV shift and increased intensity in the absorption coefficient, while the reflectivity peak decreases. These changes in optical properties and bandgap due to Eu and Y doping make SmMnO3 a promising material for advanced applications in photovoltaics, UV photodetectors, and optoelectronic devices. The ferromagnetic property and total magnetic moment of SmMnO3 are found to be increased by Eu doping. Meanwhile, the magnetic moment gets reduced by Y doping. Curie temperature calculations indicate that Eu doping increases the Curie temperature from 255.35 to 314.28 K, while Y doping reduces it from 255.35 to 187.69 K. These changes in magnetic moment and Curie temperature suggest that the doped material is suitable to be used in magnetic sensors and storage devices. The calculated elastic constants, Young’s modulus, shear modulus, Poisson’s ratio, and B/G ratio suggest that both pristine and doped compounds under study show a ductile behavior.

Synthesis and characterization of piperazine nitrate monochloride semi-organic single crystal for NLO applications

A semiorganic single crystal of piperazine nitrate chloride (PNC) was grown utilising the gradual evaporation solution technique at ambient temperature. The crystal lattice properties and molecular structure of the formed crystal of PNC were identified via X-ray diffraction examination of a single crystal and are consistent with the monoclinic crystal system with space group P21/n. Using Hirshfeld surface analysis, intra and intermolecular interactions were displayed. The FTIR spectrum analysis presented here examines the vibratory patterns of several functional sections found within the PNC crystal. The crystal exhibits a low absorbance throughout the entire visible spectrum according to studies of UV–vis-NIR absorbance and calculated band gap as well as optical constants. TG/DTA analysis was used to identify the stability and breakdown properties. This refractive index was computed using the prism coupling method. At different temperatures studies of the dielectric properties were conducted and the Vickers hardness technique was employed to investigate the mechanical properties. The grown crystal's laser-damaged threshold value was found. The Z-scan method investigates a PNC crystal’s third-order NLO behaviours. This method makes it possible to calculate the material's linear and nonlinear refractive indices. The PNC crystal exhibits strong third-order nonlinear optical properties, crucial for applications in optical switching and NLO devices.

Electronic, thermoelectric and magnetic properties of ternary telluride KAlTe2 and KInTe2 from theoretical perspective

First principles study has been applied to the anisotropic ternary KAlTe2 and KInTe2 materials. The energy of each material is optimized to the ground level through WIEN2k code and results are compared with the available theoretical and experimental findings. It is obtained from our results that materials have direct band gap and the calculated band gaps for KAlTe2 and KInTe2 are 1.68 eV and 0.931 eV, respectively. The direct band semiconductors are important for thermoelectric and optical devices. Theoretically the material KAlTe2 is investigated paramagnetic while KInTe2 is diamagnetic after applying GGA. The calculated numerical values of magnetic behavior are small, which suggests the materials exhibit weak magnetism. The semi-classical Boltzmann technique implemented in the BoltzTraP package was used to determine thermoelectric properties including the seebeck coefficient, electrical conductivity, thermal conductivity, and figure of merit (ZT). The seebeck Coefficient value for KInTe2 in N-types region is –11.99 µV/K, the chemical potential range have taken between 0.00 eV to –0.02 eV for the P-type calculated value is material 11.96–8.08 µV/K. The maximum seebeck Coefficient values for the materials KAlTe2 in the N-type region is –0.35 and 0.57 µV/K and P-type region is 5.5–6.7 µV/K, respectively. Calculated numeric values of ZT for both materials are high and materials suited for N-type doping and keeping excellent thermoelectric materials for newly developed semiconductor devices.

Molecular adsorption of chloromethane and vinyl chloride on square lattice net phosphorene – A first-principles study

The advancement of two-dimensional (2D) materials after the discovery of graphene leads to the path of various 2D materials. One such 2D material is square lattice (sql) net phosphorene. Initially, the structural and dynamic stability of sql phosphorene is confirmed with regard to the formation energy and phonon-band-spectrum. The electronic properties of sql phosphorene are explored using band structure and projected density of states spectrum. Besides, the calculated band gap value of sql phosphorene is 3.174 eV which shows the semiconducting nature of the material. Owing to the structural firmness and semiconducting nature of sql phosphorene material, it is used as a sensing element for chloromethane and vinyl chloride molecules. Evidently, the adsorption of chloromethane and vinyl chloride on sql phosphorene leads to modulating the energy band gap, electron difference density, and charge transfer, which infers changes in the electronic properties of sql phosphorene. The adsorption energy range is recorded to be −0.152 eV to −0.608 eV which confirms that the chloromethane and vinyl chloride are physisorbed on sql phosphorene. The findings ensure that sql phosphorene is a proper sensing element for the detection of chloromethane and vinyl chloride molecules.

Magnetism and Thermoelectric Properties of the Zintl Semiconductor: Eu21Zn4As18.

Compositional diversity and intriguing structural features have made Zintl phases excellent candidates as thermoelectric materials. Zintl phase with 21-4-18 composition has shown high thermoelectric performance in the mid- to high-temperature ranges. The complex crystal structure and favorable transport properties of these compounds indicate the potential for high thermoelectric efficiency. Arsenic-based Eu21Zn4As18, belonging to the Ca21Mn4Sb18 structure type, exhibits a semiconductor-like p-type transport behavior and has a calculated band gap of 0.49 eV. The compound is paramagnetic at high temperatures, with an antiferromagnetic transition occurring at T N = ∼10 K. The moment obtained from the Curie-Weiss data fit aligns with Eu2+ ions. At the same time, the field-dependent measurement at 2 K indicates complex magnetic ordering with a saturation moment consistent with Eu2+ ions. Pristine Eu21Zn4As18 exhibits an ultralow lattice thermal conductivity of 0.40 W m-1 K-1 at 873 K. Electronic transport properties measurement shows evidence of bipolar conduction across much of the measured temperature range (450-780 K). However, the Seebeck coefficient remains extremely high (>440 μV K-1) across this range, indicating the potential for high zT if an appropriate dopant is found. This work represents the first report on the temperature-dependent thermal conductivity, Seebeck coefficient, and thermoelectric efficiency of the arsenic-containing Zintl phase with 21-4-18 composition, showcasing its promise for further optimization of the thermoelectric performance.

Exploring HgO effect on structural, dielectric, optical, and radiation shielding properties of borate-based glass

Abstract Glass samples in the system 60-xB2O3+20BaO+20K2O+xHgO (0≤x≤15 mol.%) were prepared via melt quenching method. Infrared spectroscopy revealed structural modifications with increasing HgO content, characterized by a shift in the BO4/BO3 ratio. Dielectric and impedance spectroscopy studies indicated enhanced ionic conductivity with higher HgO concentrations. Optical properties, including refractive index, extinction coefficient, and optical band gap, were determined. The optical absorption edge exhibited a red shift with increasing HgO, attributed to structural changes. Refractive index measurements showed an anomalous dispersion behavior at shorter wavelengths, followed by normal dispersion at longer wavelengths. Optical band gap calculations indicated a decrease with increasing HgO content, suggesting increased disorder. The mass attenuation coefficient (MAC) and linear attenuation coefficient (LAC) were calculated using the Phy-X/PSD software. Increasing HgO content led to a significant enhancement in both MAC and LAC values, particularly at lower energies. The mean free path (MFP) exhibited a corresponding decrease with higher HgO content. Overall, the results demonstrate the potential of these glasses as effective radiation shielding materials.

Investigating the adaptability of CsMF3 (M = Ge, Si) perovskites under hydrostatic pressure for improved optoelectronic performance: A DFT-based computational study

The Cesium-based halide perovskites CsMF3 (M = Ge, Si) were examined in detail, using density functional theory evaluated ab-initio calculations, under hydrostatic pressures varying between 0 and 40 GPa. The structural, electronic, bonding, optical, anisotropic elastic, and mechanical characteristics of prospective photovoltaic materials are examined to assess their viability. The structural, thermodynamical, mechanical, and vibrational stabilities are validated through the analysis of the Goldschmidt tolerance factor, formation energy, Born stability criteria, and phonon calculations, respectively. Both the GGA-PBE model and the non-local hybrid sX potential were utilized to estimate the structural parameters and electronic energy band gaps. The calculated band gaps indicate that the compounds exhibit semiconductor behavior at ambient pressure with values 2.074 eV (2.642 eV) for CsGeF3, and 1.097 eV (0.977 eV) for CsSiF3 utilizing GGA-PBE (hybrid sX) potential. However, increased pressure reduces the band gap, resulting in enhanced conductivity and causing a shift from a semiconductor to a metallic state. The charge density map distinguishes between the ionic character of the Cs-F bond and the covalent nature of the Ge/Si-F bond. When pressure is applied, the bond strength increases, leading to a uniform decrease in bond length. The application of pressure also improves the optical functionalities, suggesting that these materials could be effectively utilized in various optoelectronic devices designed for the visible and ultraviolet spectra. In addition, hydrostatic pressure has a significant influence on the mechanical characteristics while retaining stability. Under pressure, both the ductile and anisotropic characteristics become more prominent for CsMF3 (M = Ge, Si) solids.

Optimizing photocatalysis: Tuning europium concentration in zinc oxide nanoparticles for superior performance

This work reports, improved photo catalytic performance of ZnO by band gap engineering via Eu doping (0.5–2.0 %). Single phase wurtzite structure of sol gel derived ZnO and Eu (0.5–2.0 %) doped ZnO are confirmed by XRD, FTIR and Raman spectra. Slight variation in structural parameter, FTIR stretching mode at 677 cm−1 and Raman E2 peak position indicate substitution of Eu+3 in ZnO. Calculated band gap decreases [3.05-2.89] with Eu concentration due to generation of charge trap level. Dye degradation of MO improved in Eu doped ZnO as compare to ZnO. The catalytic effectiveness is clearly shown by significant breakdown of a commonly used MO dye (at a concentration of 120 mg l−1). ZnO: Eu 2 % has a remarkable clearance rate of 99.37 %, which is explained by pseudo-first-order kinetics. The increase in oxygen radical ion concentration due to presence of Eu2O3 impurity phase in Eu 2 % doped ZnO supports MO degradation mechanism.

Advancement in the thermoelectric performance of bulk SnSe: GGA+U approach for band gap calculation and strain induced thermal conductivity

The utilization of thermoelectric technology for harnessing electricity from waste heat has received considerable interest in recent years. Nevertheless, it is essential to develop high-performance thermoelectric materials that exhibit outstanding conversion efficiency to satisfy the world's energy needs. Density Functional Theory (DFT) techniques have gained wide spread recognition as computational simulation methods for determining electronic properties within materials science. The Boltzmann transport equation, used in conjunction with DFT, serves as a valuable tool for predicting the thermoelectric characteristics of various materials. In this investigation, we conducted a comprehensive analysis of the thermoelectric properties of SnSe using the Quantum Espresso software. Generalized gradient approximations were used as the exchange-correlation functional, which approximates the exchange and correlation energies between electrons in many-body problems. The investigation of core electrons employed ultrasoft pseudopotentials. Additionally, the Hubbard correction tool was applied for the final calculation of the band gap. The optimized structure used for the investigation of the thermoelectric properties of bulk SnSe was supported by the BoltzTraP code. Thermal conductivity studies were conducted using Slack's equation, which incorporates both elastic and lattice characteristics. The examination focused on assessing the impact of changes in lattice strain on lattice thermal conductivity. Notably, a significant alteration in the thermoelectric figure of merit was observed due to the applied lattice strain.

First‐Principles Study of Structural and Elastic, Electronic, and Thermoelectric Properties of PdSe2

The thermoelectric material in orthorhombic (Pbca) phase is studied with the help of density functional theory implemented in WIEN2k. The main properties of investigated are elastic, electronic, and thermoelectric properties. The anisotropy factors obtained with the elastic constants indicate that is strongly anisotropic. The Tran and Blaha‐modified Becke–Johnson exchange potential is used for bandgap calculations. The BoltzTraP code is used to find out the thermoelectric properties of . At 300 K, the maximum value of the Seebeck coefficient is 200 μV K−1 for the hole carrier concentration of 2.5 × 1019 cm−3 and is 241 μV K−1 for the electron carrier concentration of 1.2 × 1019 cm−3. The power factor (PF) and figure of merit (ZT) are calculated for different carrier concentrations and temperatures. The optimum value of ZT for bulk PdSe2 as calculated in this work is ≈0.6 for hole carrier concentration (p = 2.6 × 1020 cm−3) at 800 K, which suggests as a potential material in thermoelectric applications at higher temperatures.

Correlation between structural modifications and physical parameters of Sb doped InSe alloys for optoelectronic applications

Bulk samples of In0.1Se0.9-xSbx (0 ≤ x ≤ 0.24) were synthesized using the conventional melt-quenching technique. The impact of Sb doping on the structural and physical properties of InSe alloys was systematically explored. The substitution of Sb at the expense of Se introduces defects and dislocations in the lattice, which significantly influence the properties of the InSeSb system. With increasing Sb content, physical parameters such as the average coordination number, cross-linking density, mean bond energy, and cohesive energy were observed to increase. Theoretically calculated band gap values lie between 1.7 and 1.3 eV. X-ray diffraction (XRD) analysis confirmed the polycrystalline nature of the alloys, revealing the coexistence of rhombohedral α-In2Se3 and orthorhombic Sb2Se3 phases. Energy dispersive X-ray spectroscopy (EDX) confirmed the elemental composition, showing the presence of In, Se, and Sb in the bulk samples. Raman and FTIR spectroscopy further validated the presence of distinct structural units and molecular bonds as a function of Sb content, confirming the coexistence of α-In2Se3 and Sb2Se3 phases alongside In–Se, Se–Se, and Sb–Se bonds. A strong correlation was established between the experimental findings and theoretically calculated parameters, including the average coordination number, mean bond energy, glass transition temperature, cohesive energy, and optical band gap. This study provides a comprehensive insight into the compositional dependence of structural and physical properties in InSeSb chalcogenide alloys, enhancing our understanding of their potential applications.

Structural, electronic and optical properties of α -Si3N4, β-Si3N4 and γ-Si3N4 using density functional theory

Density Functional Theory (DFT) has in recent years gained a lot of popularity and has become an efficient and reliable tool in the study of material properties. This is specifically due to its computational convenience and excellent results in the prediction of material properties, which is aided by the development of highly efficient and accurate functionals. DFT has successfully been applied in a vast study of material at both ground and excited states. In this study based on DFT structural, optical, electronic properties and phonon frequency of silicon nitrides of different phases were studied using the GGA as exchange-correlation functional. For the electronic band gap calculation the results was obtained using the GGA and the hybrid HSE06 respectively for α -Si3N4 with space group (P31c), β-Si3N4 with space group (P63/m) and γ-Si3N4 phase polymorph with space group (14‾3d). Results obtained for the phases α -Si3N4 shows a narrow indirect band gap while β and γ -Si3N4 indicate a wide indirect band gap material for wide possible application in high temperature and high-power applications. Cohesive energy calculation and phonon frequencies were obtained to check the mechanical and dynamic stability of the three different phases. Results obtain for density of states, partial density of states and the optical properties, such as absorption coefficient, refractive index, extinction coefficient, reflectivity and electron energy loss spectra which all show good agreement with previous studies and relative experimental data.

The electronic structure, optical, and transport properties of novel SrScCu3M4 (M = Se, Te) semiconductors

Abstract The density functional theory is used to investigate the complex relationships between the physical properties of the novel quaternary SrScCu3M4 (M = Se, Te) semiconductors. The computed negative formation energy values of these materials demonstrate their stable nature. The distribution of ELF around chalcogens and Cu atoms shows substantial localization, indicating strong covalent bonding. The phonon dispersion curves show that the materials have good structural stability with no negative frequencies. The s/p states of Se and s/p/d of Te play minor roles, while Cu-d states have a considerable influence on the valence band region. The computed energy gap values without SOC for SrScCu3Se4 and SrScCu3Te4 are 1.29, and 0.90, respectively. The predicted energy gap values with SOC for SrScCu3Se4 and SrScCu3Te4 are 1.35, and 0.87, respectively. SrScCu3Se4 is a harder and more compressible material than SrScCu3Te4, as confirmed by its higher bulk modulus. The ε 1(ω) values decrease and ultimately become negative, which suggests these materials are reflective. SrScCu3Te4 exhibits plasmon resonance at a high energy domain as compared to SrScCu3Se4, resulting in a greater loss function. The current study can establish the potential efficiency of these materials in cutting-edge optoelectronic devices.

Heterogeneous visible-light photoredox catalysis with NiCl2@g-C3N4 for induced C(sp2)-H/N[sbnd]H cross-dehydrogenative coupling

A novel photoactive NiCl2@g-C3N4 catalyst system, which effectively drives C(sp2)-H/NH bond formation between quinolin-2(1H)-ones, primary and secondary aliphatic amines under blue light irradiation. The NiCl2@g-C3N4 composite with a NiCl2 loading of 0.7wt% had the highest photoactivity, and the calculated band gap energy value is 2.56 eV The nickel ion could act as an electron acceptor enhancing carrier separation and transfer efficiency, greatly enhanced the photoreaction efficiency of g-C3N4. Preliminary mechanistic studies indicate upon visible light irradiation, the photo-generated electrons and holes act as oxidants, thereby generating amine radicals in the absence of external chemical oxidants. This provides a straightforward and efficient approach for directly 3-aminating quinoxalines-2(1H)-ones. Moreover, the heterogeneous catalyst can be recycled at least six times without significant activity loss.