Optical Conduction Research Articles

Exploring the structural, optoelectronic, elastic, and thermoelectric properties of cubic ternary fluoro-perovskites sodium based NaMF3 (M = Si and Ge) compounds for heterojunction solar cells applications

In the current research, the structural, optoelectronic, elastic, and thermoelectric properties of NaMF3 (M = Si and Ge) ternary halide perovskites compounds are computed within the DFT framework using first-principle modeling. The obtained results of phonons dispersion curves and the tolerance factor is calculated for NaSiF3 and NaGeF3 and is found to be 1.001 and 1.004 respectively, which reveals that these compounds are structurally and thermodynamically stable in the cubic phase. The elastic constants and other mechanical parameters demonstrate that these compounds are mechanically stable, hard to scratch, ductile, anisotropic, and possess resistance to plastic distortion. The band structure and density of states (DOS) demonstrate that NaSiF3 and NaGeF3 compounds are semiconductors and possess a direct band gap of 1.15 eV and 3.31 eV respectively from ‘R-R’ symmetries points. The optical properties are investigated and it is observed that the selected compounds possesses strong optical conduction and absorption coefficients and are transparent at low incident photons energy ranges. This led us to the conclusion that for high-fRequency UV devices, these compounds possess suitable applications. The thermoelectric properties indicate that both materials possess notable power factors and figures of merit (ZT), due to which their applications in solar cells can be deemed. To our knowledge, this is the first theoretical computational systematic study of structural, optoelectronic, elastic, and thermoelectric properties for NaMF3 (M = Si and Ge), which will be experimentally validated. Our findings add comprehensive insight into predicting high-performance Heterojunction Solar Cells.

Optical absorption and heat conduction control in high aspect ratio silicon nanostructures for photothermal heating applications

In photothermal heating, the temperature increase observed in an irradiated material is dependent on its optical absorption and thermal conductivity. A wide variety of studies have shown that optical absorption can be tailored using various nanostructures, including metamaterials, plasmonic structures, photonic crystals, and surface texturing. Similarly, thermal conductivity can be also tuned by nanostructures, including phononic crystals and superlattices. However, few have examined the potential for the simultaneous control of optical absorption and heat conduction to optimize photothermal heating processes. In this study, silicon hole and pillar arrays are tailored for their optical adsorption and thermal conductivity by varying their geometrical parameters. Subsequent experiments and numerical simulations reveal that the thermal conductivity of the nanostructures has a stronger influence on the photothermal heating effect than their optical absorption. Pillar arrays show a larger photothermal heating effect than the hole arrays; nevertheless, hole arrays are advantageous where connectivity is required, as in photothermal detector applications. With this understanding of the relationship between nanostructure dimensions and their photothermal properties, this analysis may guide the future design of periodic nanostructures for photothermal heating applications.

Tuning the optical properties and some surface structure of Cd-O thin film electrodeposited by two-electrode: An effect of Cobalt incorporation

The tuning of optical and dielectric parameters, structural and microstructural properties of CdO synthesized via a solution growth two-electrode cell arrangement under ambient environment, with the incorporation of Co ion into its matrix was investigated. The energy band gaps of the films was estimated in the range of 1.69 eV</=Eg</= 1.96 eV. The extinction coefficient, k for all the samples decreases as the incident photon energy increases. The films exhibit considerably high optical conduction across the photon energy with estimated power of 1013 (Omega m)-1. The elemental composition of the samples was determined using the energy dispersive x-ray spectrometry technique. The micrograph images from scanning electron microscopy technique shown that the films are polycrystalline and well-adhered to the substrates with their crystal grains evenly dispersed across the substrates’ surface. The x-ray diffraction analysis confirmed that the deposited films are of polycrystalline in nature. The films show preference for orientation along the (111) plane.

Structural and elastic investigations of ternary perovskite BaMF3 (M=Ag,Cu) compounds

Herein the first-principles modeling within the DFT framework is used to investigate the structural, optoelectronic, elastic, and thermoelectric properties of BaMF3 (M = Ag and Cu) ternary halide Perovskites compounds. The computed tolerance factors for BaAgF3 and BaCuF3 are 0.919 and 0.991 respectively, indicating that the cubic crystal phase of these selected compounds is thermodynamically and mechanically stable. It is found that both the compounds are structurally stable according to the Birch-Murnaghan fit curve for optimization. The IRelast package is used for investigating the elastic properties of both cubic compounds and the findings show that these compounds are mechanically stable, scratch-resistant, ductile, anisotropic, and resistant to plastic deformation. The Trans-Blaha modified Becke-Johnson (TB-mBJ) approximation is employed to determine electronic properties with accuracy and precision. The electronic-band structure analysis depicts a narrow band gap semiconductor nature of BaAgF3 and BaCuF3 compounds which displays indirect band gaps of 0.2 eV for BaAgF3 and 0.3 eV for BaCuF3 at the high symmetrical points from (Γ–M). Furthermore, the computations of total densities of states (TDOS) and partial densities of states (PDOS) are carried out to determine how different states contribute to the various band structures. The optical characteristics of BaAgF3 and BaCuF3 are comprehensively examined in 0-40 eV energy ranges. The selected materials possess high optical conduction and absorption coefficients at the high level of photon energies and show transparency at low incident photon energy ranges. The investigations of optical properties led us to the conclusion that BaAgF3 and BaCuF3 are suitable to use in high-frequency UV devices. The thermoelectric properties show that both materials hold high-power factors, electrical conductivity, and figures of merit (ZT), indicating that they are good thermoelectric materials. This is the first theoretical computational systematic analysis of structural, optoelectronic, elastic, and thermoelectric properties of BaMF3 (M= Ag and Cu) that will be experimentally validated to our knowledge.

Structural, elemental, and electrical conduction properties of corundum-type Mg2Co2Nb2O9

ABSTRACT is a new member of the corundum-type family. Its crystal structure is trigonal with space group . and ions share the A-site with fifty-fifty occupancy. In , exhibits a 2 + oxidation state, whereas shows a reduction in the charge state from 5 + to 4 + due to the presence of vacancy-trapped electrons in dimmer. The conductivity spectra analysis in view of various transport models states that overlapping large polaron tunneling is the predominant transport process (polaron radius 10.65 Å) in the low-temperature range (303-473 K), while for the high-temperature range (573-673 K), the conduction is intrinsic, and the carriers are primarily small polarons. The proximity between optical bandgap (∼1.60 eV) and conduction activation energy (1.64 eV) is due to the formation of intermediate energy bands near the Fermi level and their participation in high-temperature intrinsic conduction.

In/MgSe Terahertz Filters with Enhanced Optical Conduction and Light Absorption

In/MgSe Terahertz Filters with Enhanced Optical Conduction and Light Absorption

Free exciton and bound excitons on Pb and I vacancies and O and I substituting defects in PbI2: Photoluminescence and DFT calculations

A complete study of structure, chemical composition, morphology and photoluminescence (PL) is performed for multilayer PbI2 flakes. The reduction of thickness results in uneven spatial mapping of PL and Raman intensities, while the positions and shapes of the spectra do not undergo notable changes. The most intense peaks in the PL spectra are the direct free exciton (FX) peak at 2.44 eV (508 nm) and the bound exciton (BX) at 2.41 eV (516 nm). The variation of above/below-bandgap excitation has allowed to find three more defect-related peaks at 2.35, 2.19 and 2.04 eV. So far, these three BXs have not been studied. Our DFT calculations combined with the experimental results allow to clarify the origins of BX peaks as the recombination from the optical conduction band edge to the defect levels located above the valence band: 2.41 eV to O substituting I (OI), 2.35 eV to Pb vacancy (VPb), and 2.19/2.04 eV to IPb with split level. We have defined that the known absorption at 1.55 eV (800 nm) is related to VI nonradiative recombination center. The temperature behaviors allow to determine the thermal dissociation energy of FX of 0.22 eV. The dependences also show a co-interaction between defect levels.

Induced crystallization and enhanced light absorption and optical conduction in WO3 films via pulsed laser welding technique

Induced crystallization and enhanced light absorption and optical conduction in WO3 films via pulsed laser welding technique

Effect of incorporation of alkali earth metal oxide on structural, optical and DC conduction mechanism in tellurium-phosphate glassy systems

Effect of incorporation of alkali earth metal oxide on structural, optical and DC conduction mechanism in tellurium-phosphate glassy systems

Appealing perspectives of the structural, electronic, elastic and optical properties of LiRCl3 (R = Be and Mg) halide perovskites: a DFT study.

To enhance the effectiveness of materials, we are motivated to investigate lithium-based halide perovskites LiRCl3 (where R = Be and Mg) using first-principles techniques based on density functional theory (DFT), implemented in the WIEN2K code. In this study, the research makes use of the WIEN2K simulation code, employing the plane-wave and self-consistent (PWSCF) approach. The cut-off energy, responsible for distinguishing core and valence states, is established at -6.0 Ry. To guarantee well-converged solutions with 2000 K points, parameters of RMT × Kmax = 7.0 are selected, where RMT represents the smallest muffin-tin radius and Kmax denotes the plane wave cut-off. Convergence is determined to be attained when the overall energy of the system remains unchanged during self-consistent calculations, reaching a threshold of 0.001 Ry. We observe structural stability of these materials using the Birch-Murnaghan fit, tolerance factor and formation energy. The tolerance factor for LiMgCl3 and LiBeCl3 are 1.03 and 0.857, while the formation energy for LiMgCl3 and LiBeCl3 are -7.39 eV and -8.92 eV respectively, confirming these to be stable structurally. We evaluate the electronic properties of the current materials, shedding light on their nature, by using the suggested modified Becke-Johnson potential. It turns out that they are indirect insulators, with calculated band gaps of 4.02 and 4.07 eV for LiMgCl3 and LiBeCl3, respectively. For both materials, we also calculate the density of states (DOS), and our findings regarding the band gap energies are consistent with the band structure. It is observed that both materials exhibit transparency to low-energy photons, with absorption and optical conduction occurring in the UV range. These compounds are mechanically stable, according to the elastic investigation, however LiBeCl3 shows higher resistance to compressive and shear loads as well as resistance to shape change. On the other hand, LiMgCl3 exhibits weaker resistance to changes in volume. Furthermore, we discovered that none of the compounds are entirely isotropic, and specifically, LiMgCl3 and LiBeCl3 are brittle in nature. These materials appear to be potential candidates for use in optoelectronic devices based on our analysis of their optical properties. Our findings may provide comprehensive insight, invoking experimental studies for further investigations.

First-principles structural, elastic and optoelectronics study of sodium niobate and tantalate perovskites

The intensified quest for efficient materials drives us to study the alkali (Na)-based niobate (NaNbO3) and tantalate (NaTaO3) perovskites while exploiting the first-principles approach based on density functional theory, coded within WIEN2K. While using the Birch Murnaghan fit, we find these materials to be stable structurally. Similarly, the ab-initio molecular dynamics simulations (AIMD) at room temperature reveals that the compounds exhibit no structural distortion and are stable at room temperature. By using the recommended modified Becke–Johnson potential, we determine the electronic characteristics of the present materials providing insight into their nature: they are revealed to be indirect semiconductors with the calculated bandgaps of 2.5 and 3.8 eV for NaNbO3 and NaTaO3, respectively. We also determine the total and partial density of states for both materials and the results obtained for the bandgap energies of these materials are consistent with those determined by the band structure. We find that both compounds exhibit transparency to the striking photon at low energy and demonstrate absorption and optical conduction in the UV region. The elastic study shows that these compounds are mechanically stable, whereas NaNbO3 exhibits stronger ability to withstand compressive as well as shear stresses and resists change in shape while NaTaO3 demonstrates weaker ability to resist change in volume. We also find that none of the compound is perfectly isotropic and NaNbO3 and NaTaO3 are ductile and brittle in nature, respectively. By studying the optical properties of these materials, we infer that they are promising candidates for applications in optoelectronic devices. We believe that this report will invoke the experimental studies for further investigation.

Structural, optical, and electrical properties of V2O5 thin films: Nitrogen implantation and the role of different substrates

This report investigates the effect of substrate and nitrogen (16 keV N+) ion implantation on the structural, morphological, compositional, and electrical properties of V2O5 thin films which are grown by thermal evaporation on various substrates, including glass, Si, and sapphire (termed V2O5:Gl, V2O5:Si, and V2O5:Sp, respectively). Structural analysis showed the formation of the mixed (α, and β-V2O5) phases on all substrates; however, the β-V2O5 phase is highly dominant in the V2O5:G and V2O5:Si samples. A deformation in the β-phase of V2O5 thin film under ion implantation-induced strain results in a change of crystallite size. Irradiation suppresses XRD peaks in relative intensities, indicating partial amorphization of the film with defect formation. Microstructural analysis confirmed the formation of uniform-sized nanorods for V2O5:Si, whereas isolated crystallites were formed for other types of substrates. Thermal conductivity may influence the size and shapes of V2O5 crystallite forms on different surfaces. Silicon absorbs heat more effectively than sapphire or glass, resulting in nanorod formation. A decrease in optical bandgap and electrical conduction has been observed due to increased oxygen vacancies, induced electron scattering, and trapping centres on N+ implantation. The present study thus offers the unique advantage of simultaneous reduction in optical band-gap and conductance of V2O5 thin films, which is important for optoelectronic applications.

First-principles calculations to investigate structural, elastic, optical, and thermoelectric properties of narrow band gap semiconducting cubic ternary fluoroperovskites barium based BaMF3 (M = Ag and Cu) compounds

Herein the first-principle modeling within the DFT framework is used to investigate the structural, optoelectronic, elastic, and thermoelectric properties of BaMF3 (M = Ag and Cu) ternary halide Perovskites compounds. The computed tolerance factors for BaAgF3 and BaCuF3 are 0.919 and 0.991 respectively, indicating that the cubic crystal phase of these selected compounds is thermodynamically and mechanically stable. It is found that both the compounds are structurally stable according to the Birch-Murnaghan fit curve for optimization. The IRelast package is used for investigating the elastic properties of both cubic compounds and the findings show that these compounds are mechanically stable, scratch-resistant, ductile, anisotropic, and resistant to plastic deformation. The Trans-Blaha modified Becke-Johnson (TB-mBJ) approximation is employed to determine electronic properties with accuracy and precision. The electronic-band structure analysis depicts a narrow band gap semiconductor nature of BaAgF3 and BaCuF3 compounds which displays indirect band gaps of 0.2 eV for BaAgF3 and 0.3 eV for BaCuF3 at the high symmetrical points from (Γ–M). Furthermore, the computations of total densities of states (TDOS) and partial densities of states (PDOS) are carried out to determine how different states contribute to the various band structures. The optical characteristics of BaAgF3 and BaCuF3 are comprehensively examined in 0–40 eV energy ranges. The selected materials possess high optical conduction and absorption coefficients at the high level of photon energies and show transparency at low incident photon energy ranges. The investigations of optical properties led us to the conclusion that BaAgF3 and BaCuF3 are suitable to use in high-frequency UV devices. The thermoelectric properties show that both materials hold high-power factors, electrical conductivity, and figures of merit (ZT), indicating that they are good thermoelectric materials. This is the first theoretical computational systematic analysis of structural, optoelectronic, elastic, and thermoelectric properties of BaMF3 (M = Ag and Cu) that will be experimentally validated to our knowledge.

Magnetic and optical properties, electrical behavior and conduction mechanism study by CBH model of Cu(HAsO3).Te(OH)6 compound

The copper hydrogeno-arsenite tellurate material (CuAsTe) was synthesized and its magnetic properties were investigated. Thermal analyses revealed that no mass loss was recorded before 480 K. Additionally, in this current work, electrical properties based on the impedance measurements were determined. The complex impedance diagram at different temperatures demonstrated a single semicircle, implying that the response originated from a single capacitive element corresponding to the grains. The thermal evolution of the conductivity σdc displayed an Arrhenius type behavior and suggested that this material is an ionic protonic conductor at high temperature whereas the σac conductivity was indicative that the conduction mechanism is ensured by the correlated barrier hopping (CBH) model. The variation of M″ versus frequency proved to be a thermally activated dielectric relaxation process. Notably, we specified determined the direct optical band gap Eg = 2.3 eV in order to characterize the optical properties.

Monolayer TiNI with Anisotropic Optical and Mechanical Properties

Anisotropic monolayer materials have always been investigated by physical researchers. In this paper, we report a stable two-dimensional TiNI monolayer with anisotropic mechanical, optical, and electrical conduction properties. By combining the methods of non-equilibrium Green’s function and density function theory, we obtain two-dimensional TiNI materials with mechanical, optical, and electronic transport properties that depend on the lattice orientation. In addition, the maximum Young’s modulus of the single-layer TiNI can reach 160 N/m2. The calculate result of electrical transport properties also indicates the anisotropic electron transport performance of TiNI monolayer. Moreover, the electron transport intensity along the direction b is about six times the conduction intensity along the direction a. The anisotropic mechanical and optical properties, as well as the tunable band gap and special electron transport characteristics, enable a promising future for monolayer TiNI materials in nano-optoelectronics.

A liquid lens-based optical sensor for tactile sensing

Tactile sensing plays a crucial role in robot manipulation, robot interaction, and health monitoring. Because of high sensitivity, simple structure, and superior interference immunity, optical tactile sensors based on optical imaging or optical conduction have been one of the most active research. Herein, a novel liquid lens-based optical sensor (LLOS) is presented. Different with existed optical tactile sensors, the main body of the proposed sensor belongs to a variable-focus optical lens with a liquid-membrane structure, and its focal length is changed with the contact force, thereby changing the propagation direction of light and affecting the perceived light intensity of the photosensitive element. By conducting some testing experiments, the LLOS demonstrates fast response (about 0.021 s), stable dynamic response characteristics, and good linearity (R-squared is about 0.99), repeated measurement accuracy (<0.006 V), and measurement accuracy (<0.2 N). Hence, the LLOS provides a new and promising method to measure tactile and has potential application in robotics nondestructive grasping and interactive input devices.

Evaluation of the microstructure, optical properties and hopping conduction mechanism of rare earth doped Ba0.85Ca0.12RE0.03Ti0.90Zr0.04Nb0.042O3 ceramics (RE = Ce3+ and Pr3+).

The current research work examines the impact of Rare Earth (RE3+) ion substitution on the structural, optical and conduction properties of a Ba0.85Ca0.12RE0.03Ti0.90Zr0.04Nb0.042O3 (BCRETZN) (RE = Ce, Pr) ceramic compound produced via a solid-state route. The Rietveld method of the X-ray data revealed a tetragonal (P4mm) structure at room temperature for our ceramic compound. The morphology of the compound was explored using Scanning Electron Microscopy (SEM) as well as optical response and conduction behavior. The photoluminescence properties revealed that the BCPrTZN sample results in green and red photoemissions under laser excitation at 450 nm at RT. Furthermore, for the BCCeTZN sample, the photoluminescence data demonstrated that strong violet emission bands were acquired, at RT upon an excitation at 350 nm. The electrical conduction process was verified via the correlated barrier Hopping method. The scaling behavior suggests that the electrical conduction mechanism is independent of temperature. The existence of Ce3+ and Pr3+ ions in these materials could have important technological potential in new multifunctional devices.

Modeling structural, elastic, electronic and optical properties of ternary cubic barium based fluoroperovskites MBaF3 (M = Ga and In) compounds based on DFT

This work presents in detail the Ab-initio computational research work on the structural, elastic, electronic, and optical properties of Perovskite-type (Halide-Perovskites) barium-based MBaF3 (M = Ga and In) compounds. The work is based on density functional theory (DFT) within WIEN2K. Structurally both GaBaF3 and InBaF3 based on optimization of Birch Murnaghan fit are found to be stable. The IRelast package for the calculations of elastic constants (ECs) is employed for the computation of elastic properties. Mechanically these compounds are identified to be ductile, hard to scratch, anisotropic, mechanically stable, and demonstrate strong resistance to plastic deformation. The precise modified Becke–Johnson (mBJ) potential is employed for electronic properties. Band structures of these compounds possess an insulating nature of direct wide energy band gap of 5 eV for GaBaF3 and 5.1 eV for InBaF3 from X-X symmetries points. To know the contribution of different electronic states to the band structures, the TDOS and PDOS i-e (total and partial density of states) are exploited. The insulating direct wide band gap energy nature presented a straightforward direction to study the optical properties of these compounds. The optical properties, of both the compounds, were studied deeply in the energy range from 0 eV to 40 eV. These compounds possess high absorption and optical conduction at high energy ranges. Both materials are transparent to incident photons at low energy ranges. We have concluded from the optical properties investigations that these compounds are suited for high-frequency UV device applications. To our deep knowledge, this is the first systematic theoretical computation of MBaF3 (M = Ga and In) with structural, elastic, electronic and optical, properties that have yet to be verified experimentally.

Effect of lanthanum substrates on the structural, optical and electrical properties of copper selenide thin films designed for 5G technologies

In this work, copper selenide thin films coated onto glass and transparent lanthanum substrates are studied. The (glass, La)/CuSe thin films which are prepared by the thermal evaporation technique under a vacuum pressure of 10−5 mbar are structurally, morphologically, optically, dielectrically and electrically characterized. Lanthanum substrates improved the crystallinity by increasing the crystallite size and decreasing both of the microstrains and defect density of copper selenide. La substrates redshifts the energy band gap and doubled the dielectric constant values. In addition, employing Drude–Lorentz approaches for optical conduction to fit the dielectric constant provided information about the effects of La substrates on the drift mobility, plasmon frequency, free carrier density and scattering times at femtosecond level. The drift mobility increased and the plasmon frequency range is modified when La substrates are used. Verifying impedance spectroscopy tests in the microwave frequency domain have shown the ability of the La(gate)/CuSe/Ag (source) transistors performing as band pass filters. These filters are suitable for 5G technologies. The microwave cutoff frequency reached ~ 5.0 GHz at a notch frequency of 2.80 GHz of the glass/La/CuSe/Ag highpass filters.

Optical properties and current conduction in annealed (Ta2O5)0.94 – (TiO2)0.06 thin films

By sputtering the mosaic assembly of tantalum (Ta) and titanium (Ti) metal targets in the oxygen environment, (Ta2O5)1−x–(TiO2)x, x = 0.06, thin films were deposited onto the quartz, and P/boron-silicon (1 0 0) substrates, at room temperature (RT). The RT deposited films were annealed for 1.5 h, from 500 to 800 °C. Formation of the crystal structure in the films was observed at and above 700 °C annealing. Optical transmittance data, measured with the UV–Vis spectrophotometer, were used to find out the extinction coefficient (k), refractive index (nopt), and optical bandgap (Eg) of the prepared films. With the increasing annealing temperature, both the nopt and Eg values were observed, decreasing from 2.218 to 2.160, and 4.23 to 4.02 eV, respectively. The extinction coefficient of amorphous films was observed lesser than the crystalline films. The current–voltage characteristics of the prepared film assisted metal–oxide–semiconductor (MOS) structures manifest different conductions, viz., ohmic at the lower electric fields; and Schottky, Poole–Frenkel, Fowler–Nordheim tunneling and space–charge–limited current, in the intermediate to higher fields, for different annealing treatments.