Forbidden Energy Gap Research Articles

Role of grain boundary passivation in the enhancement of efficiency of copper chalcogenides thin film photovoltaic devices: A schematic review

Photovoltaic devices are expected to display peak performance if fabricated with perfect single crystals. Since surfaces break the periodicity of a single crystal, there are regions of defects, which give rise to states inside the forbidden energy gap. In polycrystalline thin films, the main structural defect is the grain boundary. The presence of grain boundaries affects the optical absorption, carrier mobility and lifetime of the semiconductor. This review focuses on grain boundary passivation in thin film photovoltaic devices based on copper chalcogenides. Achieving enhanced performance in copper chalcogenide thin film Photovoltaic devices requires effective grain boundary passivation. This approach aims to mitigate the adverse effects of grain boundaries on the optoelectronic properties of the material, leading to improved efficiency and stability in Photovoltaic devices. The abstract discusses recent developments, methodologies and outcomes related to grain boundary passivation strategies, shedding light on their significance in advancing the performance of copper chalcogenide thin film Photovoltaic devices. The exploration of grain boundary passivation in this context contributes valuable insights to the ongoing efforts in optimizing the performance of thin film Photovoltaic technologies.

Green synthesis of nitrogen-doped TiO2 nanoparticles with exposed {001} facets using Chromolaena odorata leaf extract for photodegradation of pollutants under visible light

Facet-tailored TiO2 nanoparticles (NPs) exhibit exceptional properties due to high surface energy. Conventional strategies for the fabrication of such TiO2 NPs involve harmful chemicals, which necessitates the development of environmentally benign pathways. Plant extract-assisted synthesis has emerged as a promising green alternative to conventional nanomaterial synthesis. This work introduces an innovative method for the synthesis of nitrogen-doped TiO2 (N-TiO2) NPs with exposed {001} facets using the leaf extract of a weed plant Chromolaena odorata, which is commonly known as Siam weed. The synthesis was carried out by sol-gel process with triethylamine (TEA), hydrazine hydrate and urea being the nitrogen precursors. The synthesised N-TiO2 NPs exhibited exposed {001} facets and showed a reduction in band gap. Photo-induced degradation of methylene blue dye was used to analyse the photocatalytic capability of N-TiO2 NPs in the visible range. The effect of N precursor, N dosage and light exposure time on the catalytic efficacy was studied. N-TiO2 NPs derived from TEA with 1 mol.% dopant achieved 98 % degradation in 180 minutes, while those synthesized with hydrazine and urea attained 96 % and 93 %, respectively when compared to 90 % degradation for undoped samples. The N-doping leads to significant advancement of photocatalytic effectiveness of the TiO2 NPs by introducing mid-gap levels in the forbidden energy gap that diminishes the charge carrier-recombination and boost the charge-carrier mobility of TiO2. This along with the existence of high energy facets causes a substantial advancement in the photocatalytic function in the visible region. The proposed method is a sustainable way for synthesising N-TiO2 NPs with exposed {001} facets for environment remediation applications.

Solvatochromism, electric dipole moments, optical properties and electronic structure of biphenylcarbonitrile liquid crystals

The UV–Vis. absorbance and fluorescence spectra of 4HC (4′-heptyl-4-biphenyl carbonitrile) and 4OB (4′-Octyl-4-biphenylcarbonitrile) liquid crystals were measured in 23 solvents with different polarities. As dependent on changing of solvents, while the change in absorbance spectrum of liquid crystals have less, change in fluorescence spectrum have more. Molecular interactions were quantitavely investigated by using Linear solvation energy relationships. Optical forbidden energy gap has been determined with using Tauc plot. The refractive index has been calculated with semi-empirical methods. The relationships between refractive index and Eg has been commented in n-hexane, acetic acid, water and 1,4-dioxane. The electric dipole moment has been calculated by using the Bilot-Kawski, Lippert-Mataga, Bakshiev, Kawski-Chamma-Viallet and Reichardt methods. Solvatochromic shifts showed to having large dipole moments of 4OB and 4HC LCs. Their molecular orbital energies, electric dipole moments, MEP, SAS, and reactivity properties of 4HC and 4OB LCs has been found by quantum chemical calculations. It was observed that the dipole moment of 4HC was higher than 4OB.

Photonic device application of a self-driven MXene based nanocomposite

MXene based ternary composite photonic device was fabricated and characterized for the detection of different illuminations. The single chain polymer-cobalt phthallocyanine (SCP-CoPc) carrying metallised pthalocyanine macro ring was used as a polymer for the preparation of ternary composite. The Fourier Transform Infrared Spectroscopy (FT-IR), Transmission Electron Microscopy (TEM), Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX) were used to differentiate MXene/ZnO/SCP-CoPc composite prepared. The presence of Ti, C, O, Zn and Co elements in the structure of the composite was confirmed by EDX. The electrical properties of planar interdigital coated MXene/ZnO/SCP-CoPc (1:1:1 by wt) were investigated for photovoltaic application. The photo-generated carriers contribute to the current flow, and the linear photoconductivity behaviour in current measurements with different illuminations such as 20, 40, 60, 80 and 100 mW/cm2 indicates the possible photo device use of MXene/ZnO/SCP-CoPc nanocomposite. The photocurrent increased from 20 mA/cm2 to 100 mA/cm2 with the light intensity at 0.5 V was tuned from 28 to 280 μA. The forbidden energy gap (Eg) value of the MXene/ZnO/SCP-CoPc ternary composite from optical measurements was found to be 2.36 eV. Experimental results showed that the presence of SCP-CoPc and ZnO (zinc oxide) in the ternary nanocomposite increased the ε' and ε" values of MXene. The ε′ and ε″ of the ternary composite is 13.0, 26217 at 1 kHz and room temperature, respectively. The current-time results suggest that MXene based ternary composite photonic device is a self driven photodevice as the device can detect light without any external voltage bias.

Divergent features of collective gravitational quantum excitations

In this research, we study different aspects of collective gravitational quantum excitations in the framework of the quantum multistream model. The energy dispersion of collective electrostatic (plasmon) and gravitational excitations or as we call gravity quasiparticle (GQ) are derived using the nonrelativistic and relativistic models and many parameters such as the effective mass, phase, and group speed of quasiparticle excitations are studied, in detail. It is shown that, unlike plasmons with a forbidden energy gap, all positive and negative energy values are allowed for GQs. However, unlike plasmon with a dual-tone nature of collective excitations, the GQs are found to be single-tone with either wave-like or particle-like oscillations being strongly damped. The linear phase-space evolution of GQs indicates that they evolve similarly to the classical system of particles in the center of the mass frame in which the force due to self-consistent gravitational potential plays the role of interparticle forces. It is shown that the damping of wavelike or particle-like excitations in GQ energy dispersion leads to three distinct phenomena of gravitational expansion (\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$E>0$$\\end{document}), stable matter (\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$E=0$$\\end{document}) and gravitational collapse (\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$E<0$$\\end{document}), respectively. The Hubble-Lemaitre-like relation is obtained from the generalized probability current for GQs. The quantum gravitational interference effect is also studied.

Theoretical study of optoelectronic, elastic and mechanical properties of gallium modified barium titanate (Ba1-xGaxTiO3) perovskite ceramics by DFT

In this report, we study the gallium modified Barium titanate (Ga-BTO) Ba1-xGaxTiO3 with (x = 50 %) perovskite ceramics, which have not been synthesized experimentally to date. The density functional theory-based full potential linear augmented plane wave has been employed to determine the optoelectronic, elastic, and mechanical properties of pure and modified BaTiO3. Completely relaxed 2 × 2× 2 of primitive five atoms’ cells has been used for calculations. A large cut-off energy of 120 Ry has been used to eliminate the basics of plane wave-indicating wave functions. The influence of substitution of Ga on electronic structure and optical parameters such as reflectivity, refractivity, dielectric function, optical conductivity, extinction, and absorption coefficients are analyzed and elucidated with TDOS and PDOS. The Ga modified BTO manifests a forbidden energy gap of 1.84 eV. The static dielectric constant Ɛ1(o) has values of 8.8 and 100 for pure and modified compounds respectively. Ga dopant improved the polarizing power of BTO and for the doped BTO imaginary part, Ɛ2(ω)showed a prominent peak located at 3.9 eV. The optical properties show that perovskite compound substituted with Ga is a good absorber in the ultraviolet region and the modified material has a small value of reflectivity and static refractive index 12.2. The general profiles of optical spectra of modified BaTiO3 display highly desirable features like the prominent peaks of optical conductivity obtained at 4.2 and 5.8 eV for modified BTO that make it a promising candidate for optoelectronic and spintronics. Ga-modified BTO has higher ductility, modulus (169.96 GPa), and anisotropy (2.949) than pure BTO found by analyzing their elastic and mechanical properties.

The impact of Bismuth Ion on the physical and optical characteristics of borate glasses

The bismuth doped borate (Bi2O3–B2O3) glasses were made using the melt quench process. The physico-optical characteristics, including their molar and density of the specimens were examined. The density readings were obtained using the Archimedes principle. The X-Ray differ actogram was used to verify that the specimens are amorphous. Using Tauc's approach, the optical characteristics of the specimens, including their direct and indirect forbidden energy gaps, were computed. The Urbach energy and steepness of the glass system were calculated to determine its disorderliness. The effect of Bi on physical and optical properties as density, poleron radius, forbidden energy gap, refractive index etc, were observed. The metallization criteria were used to examine the materials' non-metallic character.

Eco-friendly green synthesis of (Cu, Ce) dual-doped ZnO nanoparticles with Colocasia esculenta plant extract using microwave assisted technique for antioxidant and antibacterial activity

In the realm of biomedical applications, the inclusion of plant-derived components stands out as a critical consideration due to their non-toxic nature and antioxidant properties. In our research, we opt for Colocasia esculenta plant extract, utilizing microwave technology to create dually doped ZnO nanopowder with copper (Cu) and cerium (Ce). Authors employ XRD analysis to explore the structural attributes and crystallite size of the nanoparticles, which are found to be within the range of 16–19 nm. The surface and internal characteristics of these nanoparticles are precisely scrutinized using SEM-EDS and TEM characterization techniques. Additionally, ultraviolet-visible spectroscopy is utilized to determine the forbidden energy gap of the samples, providing insights into their potential applications in UV-protected devices. The synthesized nanoparticles exhibit significant antibacterial and antioxidant properties, highlighting their adaptability for various biomedical uses.

Anticancer potential of isovanillin-based symmetrical azine: Synthesis, structure, molecular modeling, in silico leukemia inhibition and MD simulation

Isovanillin azine, a symmetrical azine easily synthesized by reaction of 3-hydroxy-4-methoxybenzaldehyde (isovanillin) with hydrazine hydrate, was identified as a potential inhibitor of the Human T-cell Leukemia Virus type 1 (HTLV-1) protease (2B7F). The compound was characterized using FT-IR, UV-VIS, 1H NMR, and 13C NMR spectroscopic techniques, as well as by single-crystal X-ray diffraction at 100 K. Additionally, calculations were conducted on the FMOs, particularly the HOMO-LUMO, to determine the forbidden energy gap and assess the compound's properties. To properly and accurately evaluate the effectiveness of our product as an anticancer drug, we investigated its interactions with 2B7F through molecular docking experiment and MD simulation. The results indicate that isovanillin azine has the potential to effectively inhibit 2B7F, laying the groundwork for the development of targeted treatments for HTLV-1-related disorders.

Effect of Hydrothermal Reaction Temperature on the Structural and Optical Properties of CuO Thin Films

Copper oxides are one of the first semiconductors studied for device applications. In the present work, CuO thin films were deposited on fluorine-doped tin oxide (FTO) substrates via hydrothermal method without using any surfactant and the effects of reaction temperature on the properties of the films were studied. CuO thin films deposited at different reaction temperatures were characterized for their structural and optical properties using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), Raman spectroscopy, and optical absorption measurements. XRD results revealed that all the films consisted of polycrystalline CuO with a monoclinic crystal structure without any impurity phase. SEM images showed that chrysanthemum-like structures were formed, the number of which increased with increasing hydrothermal reaction temperature. EDAX measurements proved the existence of Cu and O elements and showed that all the films have Cu/O ratios close to unity. The Raman spectra confirmed the formation of crystalline CuO in all the films. From the optical absorption measurements, the direct forbidden energy gap values of the CuO thin films were found to be between 1.34 eV and 1.41 eV, depending on the hydrothermal reaction temperature.

Spectroscopic screening and performance parameters of hybrid perovskite (CH3CH2PH3PbI3) using WIEN2k and SCAPS-1d

Herein, we propose that the commonly used methylammonium cation (CH3NH3+) in CH3NH3PbI3 (MAPbI3) be replaced with ethyl-phosphonium cation CH3CH2PH3+ (EP+), allowing stronger electronic coupling between the PbI6 octahedra and the organic cation and thereby increasing its stability. This paper will examine EP + based hybrid perovskite (CH3CH2PH3PbI3 or EPPbI3) as an alternative absorber material for photovoltaic cells of high efficiency and that too at affordable processing costs. By using FP-LAPW + lo methodology as used in density functional theory (DFT), we have examined physical features such as the bandgap energy, distribution of valence electron density, DOS, and optical and thermodynamical coefficients. We also simulated the performance of solar cells by employing EPPbI3 as PVA material using SCAPS-1D. The findings of the current study viz. an absorption coefficient surpassing 104 cm−1, a direct forbidden energy gap of 1.388 eV and simulated PCE of 31.8%, is enough to support applicability EPPbI3 perovskite as a PVA material.

The effect of cobalt-doped ZnO-g-C3N4 heterostructures on photocatalytic degradation of eosin yellow dye in water under simulated solar light

The unrestricted discharge of textile chemicals in natural water sources has posed major ecological and environmental threats to our standard of living. For decades, there has been a continuous search for affordable, and visible-light driven semiconductors with the capability of harnessing the full potential of sunlight to help curb the aforementioned problem. Herein, photocatalysts based on a series of cobalt (Co) and graphitic carbon nitride (g-C3N4) co-doped ZnO were synthesized via the co-precipitation method for eosin yellow dye degradation in water under visible light. The functional groups present in the materials were determined by FTIR. Other techniques such as Ultraviolet–visible (UV–Vis) spectrophotometry, X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) were utilized to study the optical properties, structural properties, morphology and elemental composition respectively. The nanomaterials' optical analysis showed a marginal rise in absorbance in the visible region with a corresponding reduction in the forbidden gap energy from 3.10 to 2.52 eV. XRD studies showed that the nanocomposites were polycrystalline in nature and possessed the hexagonal phase of ZnO having an average crystallite size of 42 nm. From the photocatalysis outcomes, the maximum photocatalytic performance was observed for the 0.8 % Co-doped ZnO-g-C3N4 system, which degraded 96 % of the dye in 180 min, with a rate constant of 17.01 x 10−3 min−1. The incorporation of Co enhanced ZnO's outstanding photocatalytic activity in the g- C3N4–ZnO system.

Ultrasonic-assisted Co-precipitation synthesis of CoAl2O4 with different capping agents: Determination of electrical and optical features

In this study, cobalt aluminate nanoparticles were synthesized by a modified coprecipitation method using different capping agents and ultrasonic treatment. Optical, morphological and structural analyses of the samples were performed and the dielectric behaviour of the samples was investigated using the impedance spectroscopy technique in the frequency range of 10–107 Hz and at room temperature. It was determined that with the use of capping agent for NPs with 30–60 nm grain size, the optical forbidden energy gaps increased from 1.80 eV to 2.15 eV and the Co/Al ratio decreased from 0.534 to 0.362. It has been shown by Williamson Hall analysis that lattice shrinkage occurs with the use of the capping agent in the structural analysis of the materials. It has been determined that the type of capping agent is effective on the grain size, optical absorption and structural content of the final product, and especially lattice shrinkage is an effective mechanism in grain size reduction. The effect seen in the materials produced with the highest OA caused a 50 % decrease in grain size compared to the one without the use of capping agent. AC impedance spectroscopy showed that CoAl2O4 spinel structures have the inhomogeneous distribution of conductive grains with limited conductive grain boundaries and behave in accordance with Koops' model. It was determined that the use of dielectric properties in the high-frequency region improved with the use of capping agents.

Fluorescence study of Ho3+/Yb3+ ions codoped Bismuth-boro-tellurite glasses

Ho/Yb co-doped Bismuth boro-tellurite glasses were synthesized by conventional melt-quench methods. Thermal properties of the prepared samples were carried by differential scanning calorimetry. UV–VIS-IR absorption spectra were studied for the calculation of forbidden energy gap and refractive index of prepared glasses. For the study of photoluminescence samples were excited by 980 nm laser diode, intense green and red emissions were detected easily even by naked eyes. The observed intense red emission is thought to be caused by a combination of excited state absorptions between different levels of Ho ions and cooperative energy transfer upconversion from a pair of Yb donor ions to one Ho acceptor ion, in addition to the usual direct energy transfer process from Yb3+ to Ho3+.

Optoelectronic properties and optical transitions in low concentrated aluminum-doped tin oxide thin films

The structural, chemical, surface morphology, and optoelectronic characteristics of Al-doped SnO2 (ATO) films are investigated and a comprehensive analysis of the obtained results is presented. All films are shown to have a polycrystalline tetragonal rutile structure by X-ray diffraction (XRD) measurements, and the single-phase nature of the structure is proved by detailed X-ray photoelectron spectroscopy (XPS) investigations. Two mechanisms of Al incorporation into the SnO2 lattice were evident by XRD and XPS measurements. Comprehensive XPS, XRD, and Hall effect investigations showed a clear relation between the charge carrier concentration, crystallite size, and the concentration of oxygen vacancy defects. Through a comprehensive analysis of the photoluminescence (PL) measurements, we determined the positions of various defect states within the bandgap. Using a thorough analysis of the optical absorption measurements, we have successfully demonstrated the presence of four direct optical transitions with energies ranging from 3.84 to 5.10 eV, and by considering the Moss–Burstein effect and the Urbach tailing phenomenon, it was shown that the first transition energy (E1) corresponds to the direct optical transition across the Γ3+−Γ1+ forbidden energy gap. The other three transitions are ascribed to electronic transitions from the valence band states Γ5− and Γ5+ to different defect states within the bandgap.

STUDY OF PHYSICAL AND PHOTOLUMINESCENCE PROPERTIES OF ERBIUM IONS DOPED BARIUM-TELLURITE GLASSES

Tellurite base glass doped with Erbium ions have been synthesized by melting-quenching method. X-ray diffractogam is used to verification of the glassynature of samples. Differential scanning calorimetry determine the glass transition temperature. Density (ρ) of specimens was calculated by Archimedess principle. Other physical parameters as oxygen packing density (OPD), Erbium ion concentration (CL) in the specimen, molar volume (Vm), intermolecular distance Ri, Polaron radius Rp, erbium ion concentration and Molar index of refraction Rm, were computed. In order to study the optical characteristics of the specimens, for instance, coefficient of absorption, forbidden energy gap (Eg), refractive index, and Urbach Energy (E), UV-visible absorption characterizations of Ba-Te glasses was performed in the range of 340-1000 nm. PL characterization has performed for photoluminescence study.

SYNTHESIS AND STUDIES OF PHYSICAL PROPERTIES HEAVY METAL OXIDE DOPED TELLURITE BASE GLASSES

Heavy metal oxide (HMO) doped tellurite glass systems with batch matrix x-HMO -(0.9-x)TeO2-0.1%Na2O- were prepared by established melt &amp; quench teqnique. Physical properties as density, molar volume, oxygen packing density, poleron radius, interatomic distance were calculated effect of different HMO on density were observed. forbidden energy gap for direct and indirect allowed energies were estimated and further Refractive indices were calculated measured.

Physical and Luminescence Properties of Europium Ions Doped Barium Tellurite Glass

Barium tellurite (Ba-Te) base glass with and without europium ions have been synthesized by customary melting and quenching method. XRD is done for the verification of the nature of prepared specimens. DSC of the samples was done to determine the glass transition temperature. Density (ρ) of specimens was calculated by Archimedes’s principle. Other physical parameters as oxygen packing density (OPD), Europium ion concentration (CL) in the specimen, molar volume (Vm), intermolecular distance Ri, Polaron radius Rp, europium ion concentration and Molar index of refraction Rm, were computed. In order to study the optical characteristics of the specimens, for instance, coefficient of absorption, forbidden energy gap (Eg), refractive index, and Urbach Energy (E), UV-visible absorption characterizations of Ba-Te glasses was performed in the range of 340-1000 nm. PL characterization has performed for photoluminescence study.

Physical and Optical Properties of Lead-Tungsten-Tellurite Glasses

By using the melt quenching approach, a number of tellurite-based heavy metal oxide glasses codoped with varied lead oxide (PbO), (80-x)TeO2-20%WO3-xPbO (x = 5, 10, 15 and 20 mol%) compositions, have been created. By using UV-Vis-IR spectroscopy, forbidden energy gap, Urbach energy, and refractive index were calculated and the contribution of PbO to the glasses structure was investigated. Calculations were also made for physical parameters such as density, molar mass, and oxygen packing density, polaron radius, inter-ionic distance, and molar refraction. The direct and indirect optical band gaps is 3.29 to 3.33 eV and 3.2 to 3.3 eV, respectively. The fact that the nonbridging oxygen ion content rises with increasing PbO content and shifts the band edge to lower frequencies, may be the cause of a drop in the values of the energy band gap Eg.

A DFT Approach and Perspective of Sodiation in Ag2O Host: Exploration towards Sodium Batteries

Inspired by the high volumetric energy density and biocompatibility of Ag2O, the exploration of sodiation mechanism with one and two Na atom(s) per Ag2O unit cell has been carried out. Here, Na adsorbed at tetrahedral interstitial site (TIS) of Ag2O emerges to be the most stable with energy of –6.98 eV leading to the formation of Na–Ag2O compound. The advancement of Ag2O towards a metallic state is evidenced by the absence of a forbidden energy gap in the band structure plot with Na inclusion. Also, the formed compound is confirmed from PDOS plots and by analysing the charges transferred between Na, Ag and O atoms from CDDP. Further, when the concentration of Na is stepped up to two, the most stable TIS and Agsub sites exhibits an energy of –5.79 eV Na−1 atom. In this case, the Bader charge analysis reveals that Na prefers to form strong contacts with Ag and weak interactions with O, thus demonstrating the feasibility of alloying rather than the conversion product. Subsequently, NEB studies show that the surface diffusion of Na from one TIS to the adjacent unit requires a minimal activation energy thereby suggesting the suitability of Ag2O as an alloying host.