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In this article, the thermoelectric properties of five different polymorphs of gallium phosphide (GaP) such zinc-blende (zb-GaP), wurtzite (wz-GaP), sphalerite (sp-GaP), Beryllium oxide (β-BeO-GaP), and Silicon carbide (SiC-GaP) have been reported in detail. In this regard, the prerequisite electronic structure calculations have been performed in the framework of density functional theory (DFT), whereas the results for thermoelectric properties have been obtained via Boltzmann transport theory (BTT). We found that these GaP polymorphs exhibit relatively higher electrical conductivity corresponding to holes as a result larger power factors (PFs) have been realized for n-type doping than p-type. The highest values of PF corresponding to n-type doping have been recorded as 27.492 × 1010 W/mK2s, 27.999 × 1010 W/mK2s, 29.491 × 1010 W/mK2s, 15.706 × 1010 W/mK2s, and 26.557 × 1010 W/mK2s respectively, for zb-GaP, wz-GaP, sp-GaP, β-BeO- GaP, and SiC-GaP. Moreover, their PF has been further enhanced by the increase in temperature. In contrast, the Seebeck coefficients (thermopowers) have been found relatively larger for p-type doping than n-type. The relatively large thermopowers and lower thermal conductivity for p-type doping have resulted in the enhancement of Figure-of-merit (zT) by holes rather than electrons. The highest zT values have been recorded as 0.997, 1.004, 0.998, 1.001, and 1.010 in the case of zb-GaP, wz-GaP, sp-GaP, β-BeO-GaP, and SiC-GaP respectively. Our study indicates the adequate potential of these different polymorphs of GaP for thermoelectric applications.

In this report, we studied the optical and dielectric properties of lanthanum doped lead sulphide (La@PbS) nanoparticles prepared by microwave assisted synthesis method. Crystallite phase of the prepared samples was confirmed through X-ray diffraction analysis. The uniformity and homogeneity of La@PbS was recorded by SEM analysis. The particles size were found to increase with La content. The band gap values vary between 0.87 and 1.00 eV and influenced by the La concentration. Dielectric constants are highly dependent on both the applied frequency and La doping, whose values ranges between 23 and 41. The AC conductivity studies show that, they follow Jonscher’s power law relationship, and their DC electrical resistivity decreases with La concentration. The outcomes suggested that the optoelectronics properties of prepared PbS samples can be widely tuned with La doping.

The structural, optical, and dielectric properties of pure NiO and yttrium (Y) doped NiO (Y: NiO) were studied in the present article for optoelectronic application. The pristine and different concentrations of 1.0, 2.5, 5.0, 7.5, and 10 wt.% doped Y: NiO nanoparticles (NPs) were synthesized by flash combustion route. X-ray diffraction patterns (XRD), Raman spectroscopy and scanning electron microscopy (SEM) images were used to study the structural properties of as-prepared nanoparticles. The average crystallite sizes (29.8–6.7 nm) and grains size (159.2–17.9 nm) were found to be decreased with an increase in Y contents. The dislocation density (1.12–21.75 × 10−3 1/nm2), lattice strain (2.79–12.46 × 10−3) and surface area (29.48–131.13 cm2/g) were increased on increasing Y contents. Direct optical band gaps of prepared samples were estimated using the Tauc's relation in the range of 3.52–3.37 eV. Photoluminescent spectra of prepared samples exhibit spectra at 355 nm, 451–482 nm, and 493 nm emission bands, which confirm the existence of oxygen and nickel vacancies. The improvement in the dielectric constant (143), dielectric loss (1233), and loss tangent (8.67) were observed for 5.0 wt.% Y doped NiO from the dielectric analysis of the samples. The electrical conductivities of Y: NiO NPs were also improved compared to pure NiO NPs. The improvement in the optical and dielectric properties of NiO in the substitution of yttrium (Y) can be used for optoelectronics applications.

The polytypism of solids has been established as one of the most effective approaches to alter their physical properties. In this first-principles-based study, we practiced the polytypism of galliu...

Silica nanospheres have been explored much for drug delivery, photocatalysis, sensors and energy storage applications. It also acts as a template for Surface-Enhanced Raman Spectroscopy (SERS) substrates. Uniform nanostructures at low cost with high reproducibility are the major challenges in SERS substrate fabrication. In the present work, silica nanospheres were synthesized using stober method and deposited on to glass slides using Vertical deposition techniques. Different size/thickness of Silver (Ag) nanoparticles were deposited onto silica thin films using sputter deposition technique. The monodispersity of silica nanospheres and size of silver nanoparticles (10 nm, 20 nm and 30 nm) were confirmed by FESEM analysis. The structural properties were confirmed through XRD. UV–Vis analysis revealed that the plasmonic properties of Ag@SiO2 give high surface plasmons for 30 nm thickness of silver. The binding energy of Ag@SiO2 confirmed through XPS spectrum. The fabricated SERS substrates were used to detect Rhodamine 6G (R6G), Methylene blue (MB), Methylene violet (MV) and Methyl orange dyes as an analyte molecule with a limit of detection at about 10−11 mol/L. The addition of SiO2 nanospheres decreases the Ag oxidation rate and increases their stability. The maximum enhancement factor (1.5 × 107) achieved for 30nm thickness of Ag@SiO2. The results and technique establish the potential applications and reproducible SERS substrate.

The current work reports the synthesis of the Earth-abundant Copper Zinc Tin Sulfide (CZTS) absorber thin films at low temperature through modified spray pyrolysis technique without high-temperature annealing. The impact of carrier gas pressure during the synthesis of this potential solar absorbing material in the form of thin film is studied within the range of 0.10 to 0.20 Pa at a substrate temperature of 350˚C to understand the variation in its inherent characteristics. The deposited films were analyzed subsequently using X-ray diffraction, Raman spectroscopy, Scanning electron microscopy, Energy dispersive X-ray spectroscopy, Atomic force microscopy, and a UV–Vis spectrophotometer. The influence of the carrier gas pressure on the electrical property of the deposited films is also studied by analyzing its I–V characteristics. Structural and morphological analysis exhibits the formation of highly crystalline CZTS absorber film with good adherence on SLG substrate. The Raman analysis establishes the kesterite structure and the phase purity in the grown CZTS films except 0.15 Pa sample which shows the presence of a trace of Cu2S binary phase. The grain size as well as roughness of the deposited films is observed to increase with the gas pressure up to 0.15 Pa and decreased thereafter. The band gap of the film is found to decrease from 1.42 to 1.30 eV under the testing limits. The I–V characteristics of the deposited film at 0.15 Pa show higher current value than the rest of the samples. Apart from the study of influence of carrier gas pressure, this study also confirms the usage of the modified nebulizer-assisted spray pyrolysis technique as one of the economical fabrication methods for mass production of nontoxic CZTS absorber thin films that can be used in the development of environment-friendly low-cost solar cells.

Cadmium oxide (CdO) thin films doped with different yttrium (Y) concentrations have been prepared by the cost-effective spin coating technique. The effect of Y doping on structural, morphological, linear, and nonlinear optical properties of the as-prepared CdO thin films is studied. The AFM morphology of the thin films revealed grain size increase with the increase in the percentage of Y doping. From the optical properties, it is found that the films are highly transparent and the optical band gap spreads over the range of 2.3–2.8 eV. The Y doping drastically suppresses the linear and nonlinear optical properties.

The structural and phase analysis of Li@ZnO nanostructures (NSs) were tested by X-ray diffraction (XRD) and transmission electron microscopy (TEM). TEM exhibits the mixture of nanoflakes and nanoparticles at 1 wt% Li, and spherical shaped nanoparticles at 7 wt%, respectively. TEM images show the nanoflakes with thickness (12–37 nm) and diameter of nanoparticles (38–63 nm) at 1 wt%, and size of nanoparticles with 34–84 nm at 7 wt%, respectively. Raman spectra exhibit the two major modes at 107 and 446 cm−1 were credited to longitudinal phonon modes. The optical bandgaps of 3.277–3.289 eV were evaluated from the optical spectra on basis of Kubelka–Munk function F(R) using Tauc’s relation. Red shift in absorption coefficient with wavelength indicates the optical bandgap decreased with increasing Li contents above 3 wt%. The photocatalytic activity of pristine and Li@ZnO NSs were investigated in the photodegradation of organic dye methylene green (MG) solution under UV irradiation. The photocatalytic study showed significant activity improvement in the Li-doped ZnO. The sample with 7 wt% Li-doped ZnO exhibited 6.1 times higher activity compared to neat ZnO sample.

The dielectric properties of pure and yttrium-doped PbS nanoparticles synthesized by the coprecipitation chemical synthesis route have been studied by several characterizations. X-ray diffraction patterns of samples were employed to estimate the crystallite sizes and intrinsic microstrains using Williamson–Hall (W–H) plot analysis. The crystallite size and intrinsic macrostrain values were evaluated in the range of 13.7–15.9 nm and 1.09 × 10–3–1.72 × 10–3, respectively, using W–H plots. The formation of nanoparticles, nanoflakes, sponge, and nanosheets were seen via scanning electron microscope (SEM). Energy dispersive spectroscopy (EDS) of 5.0 wt% confirms the Y: PbS sample elements' chemical composition and stoichiometry. The optical band gaps increase in the range of (0.93–1.17 eV) with an increase in the dislocation density. The higher values of dielectric constant (23.6–28.0), dielectric loss (37.6–176.8), loss tangent (2.7–8.6), and electrical conductivity [ 10.2 to ( 11.7) S/m] have been reported at the lower frequency. The highest electrical conductivity values were obtained in the range of [ 4.71 to ( 4.81) S/m] for as-prepared samples. The greater capacitance and impedance values were found at 3 kHz and decrease with increasing the frequency up to 10 MHz. The current–voltage characteristic curves of undoped and Y: PbS NPs were performed under biased voltage. The space charge current density was noticed in the range of (8.7 × 10–4–4.2 × 10–4 amp/cm2) at 1.0, 2.5, and 5.0 wt% of Y: PbS samples. The enhancement in the optical band gap and dielectric and electric properties on yttrium doping in PbS compared to pristine PbS NPs makes them suitable for optoelectronic applications.

Cadmium Sulfide (CdS) is an excellent semiconductor for photonic devices and its optical and electrical properties are greatly affected by single element doping. In the current manuscript, the effect of potassium ion (K+) doping on linear and nonlinear optical traits of spray pyrolysis deposited CdS films was investigated. The X-ray diffraction (XRD) spectra reveal the increase of defects, decrease of crystallinity and crystallite size also change in growth orientation with K+ doping in CdS films. Moreover, the position of FT-Raman peaks was slightly blue shifted and morphology of films shows clusters of agglomerated CdS nanoparticles along with small size nanoparticles in the background as revealed from SEM images. The bandgap of K+-doped CdS films slightly broaden and shows improved transparency as compare to pure CdS films. The dielectric constants were found to be first decease for 2.5% wt. K+ doping and thereafter slightly increase for 5.0% wt. CdS films whereas optical conductivity decrease for all K+ doping concentrations. The photoluminescence intensity of CdS decreases and slightly blue shifted upon K+ doping, also a new emission band appears at 630 nm, indicating formation of new trap states in the bandgap of semiconductor. The 3rd order nonlinear properties elucidated through Z-scan technique reveals the increase of n2 and χ3 whilst decrease of β with increase of K+ content in CdS thin films.

Nanoscale materials are of a foremost desirability in functionalized materials research in almost all areas of science. Nanoscale materials with good biocompatibility and chemical stability possess biomedical usages which comprises drug carrier, cell/DNA parting, wastewater cleaning etc. Hence, magnesium-doped ZnO (Mg@ZnO) nanoparticles (NPs) were prepared by combustion route. Crystallization of Mg@ZnO NPs was investigated using X-ray diffraction and transmission electron microscopy. The particle sizes were in the range of 50–130 nm and 17.5–52.5 nm for x = 1 wt% and 4 wt% in MgxZn1-xO samples, respectively. The Zn2+ substitution by Mg2+ in ZnO increased oxygen vacancies and reduced free electrons concentration. The concentrations of dopant dependent optical band gaps were calculated using diffuse reflectance and found in the range of 3.258–3.278 eV. Antibacterial study of Mg@ZnO NPs was conducted against the Gram- + ve and Gram – ve bacteria and results revealed enrichment in antibacterial activity of Mg@ZnO NPs against all types of bacteria. In vivo test revealed that all Mg@ZnO NPs have no cytotoxic effects on liver and kidneys. Furthermore, photocatalytic activity was performed towards hazardous methylene green dye degradation under UV light irradiation. The presence of Mg in ZnO lattice remarkably improved its photocatalytic performance and the photocatalytic activity of Mg@ZnO ranged from 1.8 to 5.4 times higher than the activity of neat ZnO under the same reaction conditions. Facile synthesis of Mg@ZnO NPs was achieved successfully through flash combustion process and the prepared NPs were exploited for optical, biological and environmental applications. Enhancement of antibacterial, cytotoxicity and photocatalysis activity was observed in ZnO with Mg content doping. The outcomes present the Mg@ZnO NPs as an efficient material for opto-bio-environmental applications.

Lead sulfide (PbS) is having tremendous applications in the field of optoelectronics. Hence, a facile low temperature synthesis of PbS with different contents of terbium (Tb) has been achieved and investigated for structure–optic–dielectric–electrical properties. The structure confirmation was observed through the X-ray diffraction and Rietveld refinement process which approved a monophasic cubic structure. Rietveld refinement gives a best-fitting profile of the prepared products. The crystallite size was estimated to be in range of 15–21 nm. FT-Raman study also approved the single-phase PbS with all characteristic modes. For further confirmation of composition, homogeneity, and Tb in the final product, the EDX/SEM e-mapping was carried out. The morphological investigation was carried out through SEM which revealed that the shape and size are greatly influenced by Tb content addition in PbS. The energy gap (Eg) was estimated in the range of 1.42–1.62 eV for all Tb@PbS, and the largest Eg value was observed for 0.5 wt% Tb@PbS. The dielectric constant values are calculated in the range of 16–25 in the tested frequency region. The ac electrical conductivity was enhanced with frequency, and a charge transport mechanism is related to a correlated barrier hoping model in the prepared samples.

We reported a systematic study of the effects of Y doping BaTiO3 at Ba and Ti sites. We assessed the structural, electronic, and optical properties by employing first-principles calculations within the Tran–Blaha-modified Becke–Johnson (TB–mBJ) potential and generalized gradient approximation + U approaches. We calculated the lattice constants and bond lengths for pure and Y-doped BaTiO3. We explored the consequences of electronic structure and optical property modification because of Y doping in BaTiO3. Indeed, Y doping has led to various modifications in the electronic structures of BaTiO3 by inducing a shift of the conduction band through lower energies for the Ba site and higher energies for the Ti site. It was found that Y doping, either at Ba or at Ti sites, strongly enhanced the BaTiO3 dielectric constant properties. The transformation in bonding was explored via the charge density contours and Born effective charges. We used the state of art of polarization theory based on finite difference and Berry-phase approaches to investigate piezoelectricity. Y doping has increased the dielectric constants but canceled the piezoelectricity as they changed to metallic nature. We could look into the future for potential doping, preserving the semiconductor nature of BaTiO3 and increasing the permittivity with large dielectric loss.

High-quality thin film-based photodetectors containing praseodymium doped cadmium sulfide (Pr:CdS) were fabricated through spray pyrolysis and studied for various opto-electrical applications. Field emission electron microscopy (FE-SEM) revealed that the prepared films were highly compacted with an extremely fine nanostructure without any pinhole or crack. X-ray diffraction and FT-Raman spectroscopy studies confirmed the single hexagonal phase of all the films. The crystallite size was found to lie between 19 and 32 nm. Optical spectroscopy revealed that the fabricated films have low absorbance and high transmittance (in range of 70–80%). The energy gap was found to lie in the range of 2.40–2.44 eV. The PL spectra contained an intense green emission band at ~531 ± 5 nm (2.33 eV), and its intensity was enhanced by increasing the Pr doping content in CdS. The dark and photo currents of CdS increased by approximately 950 and 42 times, respectively with the addition of 5.0 wt% Pr. The responsivity (R) and specific detectivity (D*) were remarkably enhanced to 2.71 AW-1 and 6.9 × 1011 Jones, respectively, for the 5.0 wt% Pr:CdS film. The external quantum efficiency (EQE) of 5 wt% Pr:CdS films was 43 times that of pure CdS films, and the on/off ratio was 3.95 × 102 for 5.0 wt% Pr:CdS film. Its high R, D*, and EQE values, and photo-switching behavior make Pr:CdS a good contender for high quality photodetector applications.

Good quality cadmium sulfide (CdS) thin films were deposited on substrates of glass with different Cu concentrations using a sophisticated spray pyrolysis technique. Structural study confirms the formation of hexagonal phase CdS films with good crystallinity. The crystallite size was calculated to be in range from 19 to 21 nm and the texture coefficient was found to be higher along (110) plane for 1.0 wt.% CdS:Cu film. Further confirmation of hexagonal phase with improved crystallinity was approved by vibrational spectroscopy analysis. SEM mapping/EDX spectra shows the homogeneous presence of Cu in final film. SEM signify the nanostructured thin films fabrication with nanocrystallites formations. The optical transparency of fabricated films was noticed in range of 60 to 80%. The absorption and refractive indices values were estimated and found in range of 0.03 to 0.24, 1 to 3. The direct energy gap was noticed to reduce from 2.44 to 2. 31 eV by Cu doping. The PL spectra contains a single peak in range from 502 to 532 nm for pure and Cu doped CdS films, which is assigned to green emission and noted to be shifted towards lower wavelength. Dielectric constant, loss. loss tangent and conductivity were also determined and discussed. Moreover, the third order nonlinear susceptibility and nonlinear refractive index were calculated and found to be of high orders. The optical limiting study was also carried and shows noticeable effect of Cu doping. All results suggest that the CdS:Cu films are of good quality hence can be employed in opto-nonlinear devices.

Expeditious urbanization and rapid industrialization have significantly influenced the rise of energy demand globally in the past two decades. Solar energy is considered a vital energy source that addresses this demand in a cost-effective and environmentally friendly manner. Improving solar cell efficiency is considered a prerequisite to reinforcing silicon solar cells’ growth in the energy market. In this study, the influence of various parameters like the thickness of the absorber or wafer, doping concentration, bulk resistivity, lifetime, and doping levels of the emitter and back surface field, along with the surface recombination velocity (front and back) on solar cell efficiency was investigated using PC1D simulation software. Inferences from the results indicated that the bulk resistivity of 1 Ω·cm; bulk lifetime of 2 ms; emitter (n+) doping concentration of 1×1020 cm−3 and shallow back surface field doping concentration of 1×1018 cm−3; surface recombination velocity maintained in the range of 102 and 103 cm/s obtained a solar cell efficiency of 19%. The Simulation study presented in this article allows faster, simpler, and easier impact analysis of the design considerations on the Si solar cell wafer fabrications with increased performance.

Carbon (C)-coated zinc oxide (ZnO) nanoparticles (NPs) having different sizes and morphologies were successfully synthesized by a flash combustion biomimetic approach using different contents of gelatin as the medium. Structural and vibrational studies indicate that the NPs are grown in a hexagonal wurtzite structure. The amount of gelatin content has a strong effect on the growth mechanism and the physical and optical properties. The presence of C in the ZnO was clearly confirmed by Raman analysis in which the Raman bands corresponding to the presence of C were observed at ∼ 1343 cm−1 (G-band), 1580 cm−1 (D-band), and 2700 cm−1 (G′-band). At low concentrations, the NPs grew in the shape of spherical aggregates which arranged themselves in the form of a spherical flower-like structure. At 1 g of gelatin content, the spherical flower-like structure disappeared to be distributed at 3 g of gelatin content into a uniform planar spherical NP arrangement in the shape of a multi-aggregated cauliflower-like structure. At higher concentrations, the NPs rearranged themselves in the shape of a hexagonal disk or a prism-like structure. The band gap values were found to decrease with increasing gelatin content and were in the range of 3.18–3.26 eV, though it showed the dependency on the size, shape and presence of C in ZnO. Studies of the dielectric properties and ac conductivity on the prepared NPs were also carried out.

In this novel work, we discuss the effect of neodymium doping concentration on PbS thin films coated on glass substrates by a simple nebulizer spray pyrolysis method. The XRD analysis indicated that all the prepared PbS and PbS:Nd films possess polycrystalline simple cubic crystal structure along (200) preferential orientation and the estimated crystallites size tapered from 21 to 18 nm with growing Nd concentration. It is detected that Raman spectra of all films shows four characteristic mode at 186 cm−1, 281 cm−1, 326 cm−1, and 472 cm−1 certify the formation of PbS thin films. The micrographs obtained from scanning electron microscope indicated uniform particle on the surface of the films. Energy dispersive spectroscopy and mapping analyses confirmed the elemental composition. From the linear optical study by UV–Visible spectrometer exposed the absorption level of all the PbS:Nd films was constantly maintained in the whole visible and IR spectrum which is better for optical device fabrication. The rising of Nd content showed enhancement in band-gap as 2.13 to 2.41 eV. I–V characteristics of all the prepared films were done under dark and illumination conditions. Photosensitivity of the PbS films is enhanced after Nd doping, which result in enhancement of photo current. The results suggest that the proposed strategy can be applied to prepare high-performance photosensitivity thin films.

The facile synthesis of pristine and Terbium@Zinc oxide (Tb@ZnO) samples was produced by fast combustion route. The roughly spherical shaped morphology of Tb@ZnO was investigated by field emission scanning electron microscopy (FESEM) with agglomerated images of small size of particles. The dimension of particle shrinkages with increased the doping contents of Tb into ZnO lattice. The optical band gap of Tb@ZnO sample varies with the concentration of Tb and found to be decreased as 3.276, 3.267, 3.261 and 3.260 eV on increasing concentration of Tb from 1 to 5 wt%. The non-polar phonon mode with E2 symmetry was observed at 99 and 437 cm−1 while polar mode with A1 and E1 symmetry was reported at 330 and 580 cm−1, respectively, for pristine and Tb@ZnO samples. The photocatalytic activity of Tb@ZnO NPs has been investigated by the decolorization of methylene green (MG) dye under black light irradiation (367 nm). A remarkable photocatalytic performance of Tb@ZnO was noticed compared to the pure one and the highest percentage of activity was obtained for 1.0 wt% Tb@ZnO. Current outputs proposed the use of synthesized Tb@ZnO NPs in optoelectronic and photocatalyst applications.

Herein, we have facilely synthesized high purity ZnO nanoparticles by flash combustion technique in presence of different citric acid (CA) content. X-ray diffraction study rules out the existence of any extra phase except single hexagonal phase of ZnO. Further, crystallite size, dislocation density and strain values were estimated, and the crystallite size was found to be reduced from 20to 10 nm with rising the concentration of CA. Vibrational study also confirm the single phase in accordance with XRD results and revealed that the modes of vibration are slightly shifted owing to quantum size effect and relaxed nanostructure formation. To confirm the purity of synthesized ZnO the energy dispersive X-ray spectroscopy was carried out which confirm the high purity of synthesized products. Spherical nanoparticles (SNPs) morphology was confirmed through scanning electron microscopy and the size is reduced with raising the concentration of CA. TEM study was also carried out which clearly shows the formation of spherical nanoparticles (SNPs) and the mean size is around 10 nm for 1 g CA:ZnO and

Neodymium doped zinc sulphide (Nd: ZnS) thin films were coated on glass substrates at 450 °C through low cost nebulizer spray pyrolysis (NSP) method. Structure, morphology, opto-electrical characteristics of Nd doped ZnS films with various Nd doping concentrations (0%, 1, %, 3% and 5%) were studied. X-ray diffraction patterns revealed that all coated films were polycrystalline hexagonal structure with (102) as a preferential direction. SEM images showed smooth and uniform spherical grains without any cracks and pinholes. Topological view by AFM described the increasing of roughness of the film through doping concentration. EDAX and Elemental mapping images confirmed the presence of Zn, S and Nd without any other impurities. Raman spectra reveals that E1(LO), 2TO, 2LO and 3LO emission modes with corresponding to the wave number. PL spectra showed high intense visible and broad UV emission band at 463 nm and 397 nm, respectively. Thickness of the films increased with Nd doping concentration reflecting the reduction of transparency of the films from 86% to 78% for 0% and 5% of Nd. UV–Vis Spectrum was used to study the energy gap (Eg), dielectric constant(e), refractive index(n), and extinction coefficient (k) of the prepared films. Four-point probe method was used to calculate the activation energy of Nd: ZnS thin films from the graph drawn between ln (ρ) and (1/T).

Strontium-doped Cu2O thin films of different doping concentrations (0, 3, 5 and 7%) are deposited successfully with the help of Nebulizer spray technique. All the samples were characterized by XRD, AFM, Raman, UV–Vis, photoluminescence and Hall effect, and solar cell efficiency is calculated. From the XRD studies, the cubic structural phase of Cu2O is confirmed. The micrographs of AFM explain that the particles were uniformly distributed on the surface with homogeneous grains. The band gap value ranges from 2.17 to 1.95 eV as the doping concentration increases from 0 to 7%. The PL emission at ~ 630 nm also confirms the cuprous oxide phase. The deposited film exhibits p-type conductivity with low resistivity of 0.90 × 102 Ω cm and high carrier concentration of 22.7 × 1015 cm−3. A heterojunction solar cell of FTO/n-ZnO/p-Sr-doped Cu2O is fabricated, and the power conversion efficiency (η) is 0.75% for 7% Sr-doped film.

The single-layered Germanium sulfide exhibits interesting optoelectronic properties however the indirect bandgap hinders its practical applications for nanoscale optoelectronic and photovoltaic devices. Herein, we report two direct bandgap polymorphs of single-layered GeS (δ-GeS and e-GeS) and explore their optoelectronic properties using the density functional theory based computational approaches. The indirect bandgap of the intrinsic GeS monolayer (α-GeS) calculated in present study amounts to 0.76 eV, whereas the direct bandgap energies for δ- and e-derivatives of GeS have been recorded as 1.93 and 2.10 eV respectively. The optical spectra of these monolayers demonstrated a high degree of anisotropy and significantly different optical absorption, reflection, and refraction coefficients were seen in the x- and y-directions. They exhibited different plasmons energies along x- and y-directions which reveal the GeS monolayers as potential polarizers of electromagnetic radiations. Moreover, these monolayers demonstrated exceptionally large optical absorption spanning over a wide range of electromagnetic spectrum. The absorption coefficients were recorded typically larger along y-axis than x-axis. The designed direct bandgap monolayers are believed to overcome the major hurdles of single-layered GeS for nanoscale optoelectronic applications.

Nebulizer assisted spray technique has been implemented for the deposition of pure and gadolinium (Gd) doped PbS thin films at a substrate temperature of 210 °C onto glass substrate using lead nitrate and gadolinium (III) acetate as precursors. Doping percentage of Gd was varied from 0 to 5 wt% for the preparation of Gd doped films and to analyze the film property. A variety of techniques like X-ray diffraction, Raman spectrum, scanning electron microscopy, atomic force microscopy, energy dispersive X- ray, UV–Visible spectrometer, and keithley source meter were used to study the influence of Gd doping in PbS thin films X-ray diffraction revealed no change in preferential orientation of the crystal planes without any secondary phases formed for all the Gd-doped films. And also it confirmed that the nature of the films were polycrystalline with simple cubic structure. It also further confirmed polycrystalline simple cubic structure with decrease of crystallite size from 21 nm to 16 nm for the increase of gadolinium doping concentration from 0 to 5 wt%. Noticeable change in the grain size was observed for the 5 wt% of gadolinium doping with uniformly distributed spherical shaped nanosize grains fully covering the entire surface. The compositional analysis confirmed the presence of Pb, S and Gd in the films. The optical parameters of Gd doped PbS thin films such as band gap energy, refractive index; extinction co-efficient, and real and imaginary parts of dielectric constant were determined using transmission, absorption and reflectance spectra in the range of 300–2400 nm. A maximum value of photo current was observed for 5 wt% gadolinium doped film.

Different concentrations of Pt doped PbS nanostructures synthesis has been attained facilely by chemical route. X-ray diffraction (XRD) and FT-Raman spectroscopy analyses confirms the structure. After close inspection and indexing of diffraction peaks, the absence of additional peak owing to any contamination or free Pt in final products was confirmed. XRD data was further used to evaluate the lattice constants, crystallite size, density and strain to see the effect of Pt on these. Calculated lattice parameters confirm the single cubic phase, which was in correlation with vibrational modes analysis. The crystallite size was calculated in range from 9 to 11 nm. For further confirmation of Pt doping and its homogeneity in final product the EDX/SEM mapping was carried out and approved the homogeneous presence of Pt in PbS. SEM study revealed that the morphology is changing from nanoparticles (NPs) to nanosheets (NSs). Diffused reflectance spectra (DRS) were measured for powdered samples and energy gap was estimated up to 1.32 eV. Photoluminescence spectra was recorded and shows an intense green and broad red emission bands at 518 and 700 nm, correspondingly. The values of dielectric constant are found in range of 18–28. Total ac electrical conductivity is rising with applied frequency. The energy gap value suggest the application of synthesized Pt:PbS NPs and NSs in solar cell.

In current article authors aim is to present an insight on structural, opto-nonlinear-limiting properties of Cadmium sulfide (CdS) thin films affected by various concentrations of tellurium (Te) doping. Hence, the thin films of pure and Te:CdS were fabricated by spray pyrolysis technique by keeping the substrate at 300 °C. X-ray diffraction and FT-Raman spectroscopy analyses confirmed the hexagonal phase of CdS. The values of Lave, ρave and eave are found in range of 18–20 nm, 2.6–3 nm−2 and 1.7–1.9, respectively. Furthermore, the energy dispersive X-ray spectroscopy/scanning electron microscopy mapping (SEM) confirmed the presence and homogeneous doping of Te in CdS. SEM study shows that the fabricated films are free from any pin holes and possess very fine nanostructures. The optical transparency of grown films was noticed ~ 70%, which is quite impressive for colored materials. The absorption index, refractive index values are found in range of 0.04 to 0.25, 1.25 to 3.2 in 200 to 2500 nm wavelength region. The direct energy gap of CdS was noticed to be reduced from 2.44 to 2.35 eV (ΔEg = 0.09) with Te doping content. Photoluminescence emission spectra contains an intense green emission band at ~ 528 ± 4 nm. The dielectric constant and optical conductivity were noticed in range of 1.5 to 10 and 0.02 to 0.6 (× 105), respectively. The values of third order susceptibility and nonlinear refractive index was found of the order of 10−10 esu. The output power of the 532 nm laser passed from films is found to be reducing with increasing the Te content in CdS films. Hence, the deposited films of Te:CdS will be more applicable as optical limiter in sensor device protection from intense lights.

Dimensionality reduction has been proved as a feasible route to enhance the performance of thermoelectric materials for renewable energy applications. In this article, we investigate the effect of dimensions reduction on thermoelectric properties of GeSe using the density functional theory and Boltzmann transport theory based first-principles approaches. These investigations have been carried out for bulk (3D) and three polymorphs of single-layered (2D) GeSe (such as α-GeSe, β-GeSe, and γ-GeSe). Calculations of energetic stability demonstrated the 2D-GeSe as stable as the 3D-GeSe. The arrangement of bands within the electronic band structures of 3D and 2D GeSe showed them as indirect bandgap semiconductors. The β-GeSe and γ-GeSe exhibited wider energy bandgap and consequently large Seebeck coefficients than the 3D-GeSe and α-GeSe. The reduction in structural dimensions stimulated a sharp increase in electrical conductivity and Seebeck coefficient (particularly for β-GeSe and γ-GeSe) which has resulted in large power factor. The room-temperature thermoelectric figure of merit (ZT) of 3D-GeSe, α-GeSe, β-GeSe, and γ-GeSe of magnitude 1.02, 0.83, 1.00, and 1.10 respectively have typically broken the benchmark value of ZT ≈ 1. The ZT of these materials is sensitive to change in temperature and has been recorded as large as 1.72 for γ-GeSe at a low temperature of 150 K. The large power factors and ZT of single-layered GeSe reveal the dimensionality reduction as a feasible approach for enhancing the performance of thermoelectric materials for renewable energy applications.

Undoped and rare earth Neodymium (Nd) doped cuprous oxide (Cu2O) thin films were prepared by electrodeposition method. The prepared film's structural, morphological, optical and photosensitive properties were analyzed by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, ultra violet-visible and I-V measurements. The fabricated Cu2O:Nd films exhibited polycrystalline nature with cubic crystal system, and favorably grown along (111) orientation. Crystallite size was decreased from 56 nm to 30 nm with Nd concentrations. Raman spectrum confirmed the Cu2O phase of the prepared films. The morphological analysis showed pyramidal shaped particles for the undoped Cu2O thin film. The energy gap was reduced from 2.04 eV to 1.89 eV as Nd doping level was increased. From photoluminescence spectrum a high intense peak was observed at 619 nm which confirms the optical quality of Cu2O phase. The dielectric constant was increased by increasing the Nd doping concentration from 0 to 5%. In photosensitivity analysis an increase of photo response with respect to illuminated current was observed.

The inner transition metal (ITM) neodymium (Nd)-doped tin sulfide (Nd:SnS) thin films with various Nd concentrations were coated by nebulizer spray pyrolysis (NSP) technique at 350 °C. All the coated films were analyzed for their structural, optical and photoelectrical properties. X-ray diffractometer (XRD) study showed (111) direction as the highly preferred orientation with orthorhombic crystal structure for all the films. The intensity of the peaks was found to increase until 5 at% Nd doping and then reduced for higher (7 at% Nd) doping concentration. Atomic force microscopic (AFM) images of the films proclaimed an increase in the surface and line roughness of the films by increasing Nd concentrations. Optical analysis on the films showed a variation in energy gap from 2.05 to 1.69 eV when the doping concentration increased from 0 at% to 7 at%. At 5 at% Nd doping, the photoluminescence (PL) spectra displayed a single strong emission peak at 723.1 nm with enhanced intensity corresponding to near-band-edge emission. All the SnS thin films exhibited p-type behavior with the lowest resistivity of ~ 4.311 Ω·cm and high carrier concentrations of ~ 1.441 × 1017 cm−3 for 5 at% Nd doping level as observed from Hall effect studies. Furthermore, fluorine-doped tin oxide (FTO)/n-CdS/p-Nd:SnS hetero-junction solar cells were prepared and the current–voltage curve in dark and light condition was obtained for the device. An efficiency of 0.135% was observed for the solar cell fabricated with 5 at% Nd-doped SnS thin film.

Improving the performance of thermoelectric materials for clean energy production via structural manipulation is considered as an effective route to advanced thermoelectrics. Here, we report the im...

The low-cost and nontoxic single-layered SnS has been recently predicted as a promising material for cutting-edge nanoscale optoelectronic and photovoltaic applications beyond the graphene and phosphorene. In this article, we assess the optoelectronic properties of five derivatives of single-layered SnS (such as α-, β-, γ-, δ-, and e-SnS) using first-principles calculations. While the single-layered SnS (α-SnS) itself is an indirect bandgap semiconductor, its derivative δ-SnS demonstrated a direct bandgap and e-SnS a nearly direct bandgap which makes them promising over phosphorene. This new class of monolayers exhibits structural anisotropy along diagonal components of magnitude 0.098, 0, 0.24, 0.007, and 0.036 for α-SnS, β-SnS, γ-SnS, δ-SnS, and e-SnS respectively. The large degree of in-plane anisotropy has generated different bands dispersion and effective mass of charge carriers along the 100- and 010- directions that evolve interesting effects on their optoelectronic properties. The optical spectra of the SnS monolayers have been found significantly different along the x- and y-axis. Investigations of the excitonic binding energies indicated that the designed monolayers exhibit thermally stable excitons. The onset optical absorption energies occur over a wide range of the visible part of the electromagnetic spectrum which is appealing applications in optoelectronic and photovoltaic devices. The refractive indices and reflectivity spectra have been found significantly different along x- and y-directions that may find suitable applications in optical polarizers, filters, and shields against UV radiations. The present study is believed to provide useful guidance for the applications of SnS monolayers (δ-, and e-SnS in particular) in direction-dependent nanoscale optoelectronic and photovoltaic devices beyond phosphorene and graphene.

In the current work, the authors studied a hybrid organic-inorganic photodiode combining n-type monocrystalline silicon (n-Si) and indigo dye where the natural dye indigo has been applied as an interfacial layer between Gold (Au) and n-Si. The electrical and photo-response characteristics of photodiode based on indigo dye were investigated through current, conductance and capacitance studies measured under the wide illumination intensity and frequency ranges. The frequency dependency of capacitance-voltage (C-V) and conductance-voltage (G-V) characteristic properties of the Au/Indigo/n-Si photodiode was examined in the frequencies varying from 100 kHz to 1 MHz in view of the effects of series resistance (Rs), the concentration of donor atoms (Nd) and density of interface states (Nss). The C-V and G -V studies indicate that the Nss and Rs are key factors which are strongly influencing the electrical properties of the fabricated Photodiode. From the obtained results, the fabricated Au/Indigo/n-Si photodiode can be a promising contender for electro-optic device engineering.

Transparent conductive oxides (TCOs) are having emerging applications in optoelectronic technology. Hence, herein, we have designed and fabricated the cadmium oxide (CdO/FTO) TCO films with different concentrations of Lanthanum (La) through a facile spin coating technique. The crystal system and phase confirmation of fabricated films was analyzed by X-ray diffraction analysis. The values of D 200 are found in the range of 25–31 nm indicates nanostructured thin films fabrication. EDX/SEM mapping revealed the presence of La and its homogeneity in CdO film. Atomic force microscopy was carried out to investigate the effect of La doping on surface topography of CdO films. The average values of grain size were estimated in the range of 7.56–10.95 nm along with surface roughness in range of 15.25–17.56 for pure and La-doped CdO films. The optical transparency of films was noticed in range of 75–85% in the NIR region. Direct and indirect band gap values are found in the range of 2.55–2.8 eV and 2.0–2.4 eV, respectively. The dielectric constant, loss, refractive and absorption indices were also calculated. Moreover, the linear, nonlinear susceptibilities and refractive index values were estimated and found in the range of 0.1–3, 1 × 10−12 to 1.6 × 10−7 esu and 2 × 10−12 to 1.28 × 10−8 esu, correspondingly.

Linear and nonlinear optical properties of ammonium dihydrogen phosphate (ADP, NH4H2PO4) crystal are tailored by employing environmental growth in presence of urea and explore its applicability for photonic device applications. The structural parameters of pure and urea influenced ADP crystal has been determined by single crystal X-ray diffraction technique. The energy dispersive spectroscopic analysis has been employed to examine the constituent elements of grown crystal. The consequence of urea surrounding on optical transparency of ADP crystal has been examined within 200–1100 nm by means of UV–vis spectral analysis. The enhancing effect of urea on second harmonic generation (SHG) efficiency of ADP crystal has been determined using the Kurtz-Perry test. He-Ne laser assisted Z-scan technique has been employed to assess the third order nonlinear optical (TONLO) properties of urea affected ADP crystal at 632.8 nm. The magnitude of TONLO parameters (nonlinear refraction (n2), nonlinear absorption (β) and cubic susceptibility (χ3)) has been evaluated using the Z-scan transmittance data. The thermal stability of urea influenced ADP crystal has been experimentally evaluated by means of simultaneous thermogravimetric and differential thermal analysis.

The current investigation is aimed to explore the enhancing effect of increasing concentration of amino acid L-alanine (LA) on decisive optical traits of zinc thiourea chloride (ZTC) crystal. The most commercial slow solvent evaporation technique has been adapted to grow pure and LA influenced ZTC crystals at room temperature. The powder X-ray diffraction analysis has been carried out to determine the crystallographic data and analyze the crystalline phase and purity of pure and LA influenced ZTC crystals. The constituent elements of grown crystals have been evaluated by means of energy dispersive spectroscopic technique. The influence of LA on optical transparency of ZTC crystal in range of 190–1000 nm has been ascertained by means of UV-visible spectral analysis. The optical band gap of grown crystals has been evaluated using the transmittance data to discuss the technological impetus of grown crystals for optical devices. The Kurtz-Perry test has been performed to determine the positive impact of organic ligand of LA on second harmonic generation (SHG) efficiency of ZTC crystals. The SHG efficiency of LA influenced ZTC crystal is found to be remarkably higher than pure ZTC and potassium dihydrogen phosphate crystal materials. The effect of LA on photoluminescence nature of ZTC crystal has been investigated in the range of visible region. The impact of LA on temperature dependent dielectric response of ZTC crystal has been investigated within the range of 30–90 °C.

Sol–gel spin coating is applied to fabricate the pure and different concentrations of aluminum (Al)-doped ZnO films on high-quality silicon substrates. All films are showing high crystallinity in X-ray diffraction study, and lattice constants were obtained using PowderX software. The value of crystallite size was found in range of 20–40 nm. EDX/SEM mapping was performed for 2 wt% Al-doped ZnO film, which shows the presence of Al and its homogeneous distribution in the film. SEM investigation shows nanorods morphology all over the surface of films, and the dimension of nanorods is found to increase with Al doping. The E(g)dire. values were estimate in range of 3.25–3.29 eV for all films. Linear refractive index was found in range of 1.5–2.75. The χ1 value is found in range of 0.13–1.4 for all films. The χ3 values are found in range of 0.0053 × 10−10 to 6.24 × 10−10 esu for pure and doped films. The n2 values were also estimated. These studies clearly showed that the properties of ZnO have been enriched by Al doping, and hence doped films are more appropriate for optoelectronic applications.

In present work, bulk size (∼5 cm in length and 2 cm in dia.) single crystal of glycine zinc sulfate (GZS) was harvested from Sanakaranarayan - Ramasamy (SR) technique. The harvested crystal was exposed to in-depth study of its physical properties such as: optical, nonlinear and mechanical. Moreover, the DFT is also applied to study the molecular geometry, optical and nonlinear characteristics. XRD study confirms the formation of GZS crystal which was further confirmed through vibrational analysis. Optical absorbance and transmittance measurements were carried out. The grown crystal was found to be ∼80% transparent in wavelength from 300 to 950 nm and the band gap was estimated to be ∼4.6 eV. The respective μtot and βtot values are obtained about 3.6 times and 15 times larger compared to urea which confirm the application of GZS in NLO devices. The robust chemical etching and mechanical properties has been studied by applying different models.

In this work “solve two problems with one single action” strategy was implemented for degradation of industrial dye Amaranth and enhanced blue-green emission for opto-electronics applications in Cu2+ doped ZnO materials. The different concentrations (weight (wt) %) of Cu2+ doped ZnO materials have been synthesized by the thermal spreading method. The as-prepared ZnO and Cu2+ doped ZnO materials have effectively confirmed by various spectroscopic methods. The crystalline phase, surface morphology, compositions of elements and energy bandgap were studied systematically enquired by PXRD, SEM, EDS and UV-vis spectroscopic analysis, respectively. With the dopant concentration, 18 wt% of Cu2+ doped ZnO revealed outstanding photocatalytic performance to the degradation of Amaranth under visible light irradiation with an efficacy of about 97%. Likewise, 18 wt% of Cu2+ doped ZnO shows an strong blue-green emission at around 495 nm owing to the internal oxygen vacancies. The present work gives some clue; it may be used as a proficient photocatalyst for degradation of dyes and luminescent material for optoelectronics applications.

The undoped and terbium (Tb)-doped SnO2 thin films are coated on the glass substrates using the nebulized spray pyrolysis (NSP) technique. The crystallite size is calculated using the Williamson-Hall method and is found to be decreased from 80 to 56 nm with the increase of Tb doping concentration. Atomic force microscope (AFM) images show the spheroidal shape of the grains. The elemental analysis of the samples was investigated by energy dispersive analysis of X-rays (EDX). An increase in absorbance and decrease in bandgap values provide more photon absorption which enhances the photocatalytic reaction. The PL studies reveal the creation of more defect levels by doping which provides more active sites for catalyzed reactions. The Tb doping with SnO2 improved the rate constant about 0.015/min, and a maximum photocatalytic dye degradation efficiency of 85% against methylene blue dye was observed. Therefore, the fabricated films found potential applications for photocatalysis that enable them to chemical industries.

In this research work, optoelectronic properties of Indium bismuth selenide (InBi2Se4) thin films are studied for their potentials for photovoltaic applications. The InBi2Se4 films are prepared via a thermal co-evaporation technique on glass substrate using Bi2S3 powders and indium granules. The as-deposited films are then annealed at different temperatures to convert into InBi2Se4 thin films. Results show that the obtained InBi2Se4 films possess excellent optoelectronic properties as an optimum bandgap of 1.2 eV was obtained for the film annealed at 350 °C. Based on characterisation results of current and voltage realiationships, both as-deposited and annealed InBi2Se4 thin films show a linear relationship between current and annealing temperature. It was also noted that with increasing grain-size of the film, the current is also increased at a fixed applied voltage.

Pure and potassium iodide (KI) doped hydroxyapatite (HAp) nanostructures were prepared through a facile microwave route. Field emission - SEM (FESEM) confirm low dimension nanorods (NRs) morphology of final products. The average dimension of NRs is may be in the range of 10–20 nm. Predominant single segment was approved by XRD and EDX analyses. Lattice constants, crystallite size, density of dislocations, strain and % of crystallinity were determined and the average crystallite size is observed in 9–16 nm range and degree of crystallinity is observed to be high viz. ~ 59% for 30% KI doped HAp. Vibrational studies were done through FT-IR and FT-Raman spectroscopy and confirm the phase of HAp. The catalytic activity of all samples is done in bioremediation of methylene blue using Stenotrophomonas maltophilia strain Kilany_MB. These results suggested that HAp and KI-HAp as a promising nano-catalyst in bioremediation of water from methylene blue.

This work reports an impact of novel Terbium (Tb) doping on physical characteristics of NiO nanostructured films. The doping concentrations of Tb varied from 0 to 5.0 wt% in NiO system and are characterized using various characterization techniques. Thin films show the cubic structure preferred orientation along (111). Sizes of crystallites of films increases with Tb doping contents and strain of the films decreases. Optical constants (such as energy gap, absorption and refractive indices) are examined as a function of Tb doping concentrations. Optical band gap showed a blue shift with Tb doping concentrations. In addition, 3rd order nonlinear susceptibility and refractive index have been noticed in range of 1.78 × 10−14 -6.71 × 10−11 esu and 7.62 × 10−12 - 5.81 × 10−10 esu; respectively. Room temperature photoluminescence spectra of films reveal band-to-band transitions in UV region. Above opto-nonlinear investigation of Tb:NiO nanostructured thin films reinforce the potential candidate for optoelectronics applications.

Herein, we report samarium (Sm) dopant concentration effect on Cu2O films characteristics prepared by electrodeposition method. XRD patterns of the films indicated that pristine and Sm:Cu2O films have polycrystalline cubic structure with (111) preferred orientation. It was seen from the SEM photographs pinhole free dense triangle shaped grains for undoped Cu2O thin films and the grain size was decreased as concentration of samarium was increased. Raman spectroscopy showed peaks at 108, 146, 217, 413 and 637 cm−1 which conformed the Cu2O phase formation and intensity of the peaks was decreased with a increase in dopant concentration. UV–Vis spectra exhibited that the absorption value of Cu2O films is increased gradually with reduction in band gap value for the increase of samarium content. Photoluminescence (PL) spectra revealed that all films display a visible light emissions and its intensity was reduced due to increase in doping concentration. Photosensitivity observation study indicated that the photocurrent of deposited Cu2O films was increased along with the increase in dopant material concentration.

In this study, we investigated the monocrystal growth and characteristics of pure and methyl violet (MV) dyed zinc(tris) thiourea sulfate (ZTS) large size single crystals. The morphology of ZTS was modified in the presence of MV dye. The crystals were crushed for a finite time to obtain powders for X-ray diffraction analysis and the lattice parameters were determined. The crystals were analyzed based on Fourier transform-Raman spectroscopy measurements and the vibrational modes were identified. Some extra vibrational modes were observed due to the presence of the MV dye. Ultraviolet–visible–near infrared optical absorbance measurements were recorded and the band gap was calculated. A large band gap ∼4.31 eV was obtained for the ZTS crystals, which supports their possible application in electro-optic devices. Two absorption bands at around 584 nm (sharp) and ∼362 nm (broad) were also observed in the dyed crystals but not in the pure crystals, thereby indicating the interaction between the dye and ZTS. Photoluminescence (PL) emission studies were conducted at an excitation wavelength of 360 nm. PL emission peaks were observed at ∼433 nm in the pure crystals, and at ∼421 and 444 ± 5 nm in the dyed crystals. Differential scanning calorimetry demonstrated the increased melting temperature of ZTS in the presence of the dye. The dielectric constant, ac electrical conductivity, and mechanical strength were higher for the dyed crystals. Our results suggest that the dyed crystals may be more suitable for applications in opto-electronic devices compared with the pure crystals.