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Mg-Doped ZnO and Zn-Doped MgO Semiconductor Nanoparticles; Synthesis and Catalytic, Optical and Electro-Optical Characterization
摘要： A series of MgxZn1 – xO and ZnxMg1 – xO (mol %) were synthesized by the sol–gel method. All the synthesized nanoparticles were investigated as catalyst in the one-pot, three-component Biginelli condensation reaction of benzaldehyde, ethyl acetoacetate and urea under heterogeneous conditions. Findings revealed Mg0.007Zn0.093O (Zn7) as the best in the mentioned condensation reaction. Zn7 was characterized by FT-IR, SEM, CHN, and XRD. In addition, linear and nonlinear optical properties of MgxZn1 – xO and ZnxMg1 – xO thin films and their colloidal solutions were studied. Using an exact numerical method, some photo-physical properties of the prepared films such as dispersion curve, absorption spectrum, optical permittivity and optical band gap were attained and compared. Finally, using z-scan method at low laser irradiation, thermo-optical effect has also studied and a nonlinear refractive index due to this effect was attained. Doping effect on the optical properties was also investigated physically. It was found in both the particles groups, increasing the doping percent reduces the band gap and it suggests new optoelectronic materials with a spectrum of optical properties.
关键词： z-scan,ZnxMg1 – xO,MgxZn1 – xO,catalyst,optical band gap,nanoparticles,permittivity
更新于2025-09-16 10:30:52
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Influence of 2-Amino-4-methylpyridine and 2-Aminopyrimidine Ligands on the Malonic Acid-Cu(II) System: Insights through Supramolecular Interactions and Photoresponse Properties
摘要： Two Cu(II)-malonate complexes with 2-amino-4-methylpyridine (complex 1) and 2-aminopyrimidine (complex 2) auxiliary ligands were synthesized, and their single-crystal X-ray diffraction structures were established. Change in the auxiliary ligand exhibits substantial structural variation in the present complexes. Complex 1 shows a one-dimensional anionic copper-malonate moiety connected by the malonate bridge, whereas complex 2 is a mononuclear one. For both the complexes, auxiliary ligands are attached with the Cu-malonate moiety through various noncovalent interactions. Optical band gap, electrical conductivity, and photosensitivity of complexes 1 and 2 were measured, but the values of electrical parameters of the complexes significantly differ from each other. However, the magnitudes of electrical parameters increase several times for both the complexes when they are exposed under visible light, though the values of light sensing parameters of complex 1 were found to be higher than those of complex 2. Density functional theory calculations for complex 1 were carried out to support the experimental result.
关键词： 2-aminopyrimidine,electrical conductivity,Cu(II)-malonate complexes,density functional theory,2-amino-4-methylpyridine,optical band gap,noncovalent interactions,photosensitivity
更新于2025-09-16 10:30:52
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Europium-doped boro-telluro-dolomite glasses for red laser applications: Basic insight into spectroscopic traits
摘要： Naturally abundant minerals and lanthanide-doped synthetic boro-tellurite networks have become prospective efficient laser hosts because of the synergy between them. Driven by this idea, Eu3+-doped boro-telluro-dolomite (BTD) glasses were prepared via the melt-quenching method. The spectroscopic traits of as-quenched samples were analyzed though experimental and theoretical studies. The result from the derivation of absorption spectral fitting (DASF) model demonstrated the direct allowed transition in the glasses. Moreover, the photo-luminescence spectra of the sample containing 1.0 mol% of Eu3+ (BTD1.0Eu glass) revealed a prominent red peak at 611 nm (assigned to 5D0 → 7F2 transition in Eu3+ ion) with a large stimulated emission cross section (7.15 × 10?22 cm2) and a high luminescence branching ratio (61.5%). Furthermore, the attained CIE color coordinates (0.637, 0.363), which lie near the standard red hue (0.67, 0.33), together with high quantum efficiency (92.7%) affirmed the effectiveness of BTD1.0Eu glass as a potential red laser host.
关键词： Boro-telluro-dolomite glasses,Red emission,Europium ions,Judd–ofelt analysis,Radiative parameter,Optical band-gap energy
更新于2025-09-16 10:30:52
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Laser irradiation-induced structural, microstructural and optical properties change in Bi-doped As <sub/>40</sub> Se <sub/>60</sub> thin films
摘要： The laser irradiation of thermally evaporated As40Se55Bi5 and As40Se45Bi15 thin films was found to be accompanied by structural changes which in turn changed the optical constant. The thin films under investigation were characterized by the X-ray diffraction method to study the structural change and the surface morphology was checked by field emission scanning electron microscope. The composition of the films was verified from the energy dispersive X-ray analysis. The changes in optical properties due to the influence of laser irradiation were calculated from the transmission spectrum recorded by UV–Visible spectrometer in the wavelength region 400–1200 nm. The decrease in optical band gap (photodarkening) is explained on the basis of density of state model proposed by Mott–Davis. The Raman analysis showed the Raman shift and symmetric stretching vibration of As–Se.
关键词： thin films,optical properties,optical band gap,Chalcogenides,laser irradiation
更新于2025-09-12 10:27:22
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p-type Cu3BiS3 thin films for solar cell absorber layer via one stage thermal evaporation
摘要： Ternary copper sulphides, especially copper-bismuth-sulphide (Cu-Bi-S), are alternative solar absorber materials due to their earth-abundant and non-toxic constituent elements, compared to the conventional copper indium gallium sulphide and cadmium telluride films. In this study, Cu-Bi-S thin films were deposited onto soda lime glass substrates using a one stage co-evaporation process from Cu2S and Bi2S3 sources, with the deposition temperatures varied from room temperature to 400°C. X-ray diffraction analysis confirmed that Cu3BiS3 was the dominant phase in the Cu-rich films, and the crystalline quality of the films was significantly improved with increasing the deposition temperature. An optical bandgap of 1.4 eV was achieved for the film deposited at 400°C, which demonstrated a Hall mobility of 3.95 cm2/V-s and a carrier concentration of 7.48 × 1016 cm-3. Cu3BiS3 films deposited at 375 and 400°C were implemented into superstrate solar cell structures (glass/ITO/n-CdS/p-Cu3BiS3/Al).
关键词： p-Cu3BiS3,optical band gap,thermal co-evaporation,thin film solar cell,absorber layer
更新于2025-09-12 10:27:22
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Alloyed Ag2SexS1-x quantum dots with red to NIR shift: the band gap tuning with dopant content for energy harvesting applications
摘要： Alloyed quantum dots have pulled in a large consideration because of their fascination from visible to near infrared regime. In this work, quantum dots of alloyed Ag2SexS1-x (x = 0, 0.4, 0.6, 1.0) system are synthesized by making use of a simple intermediate temperature method. The structure and morphology of Ag2SexS1-x quantum dots are examined through X-ray diffraction, Fourier-transform infrared spectroscopy, transmission electron microscopy, and Raman spectroscopy. The X-ray diffraction data indicates monoclinic and orthorhombic structure of Ag2SexS1-x quantum dots. The size and composition controlled optical bandgap of Ag2SexS1-x quantum dots is meticulously looked into by Ultraviolet-Visible-Near Infrared absorption spectroscopy. The size of alloyed Ag2SexS1-x quantum dots varies from 3.5 nm to 4.8 nm. The bandgap of Ag2SexS1-x quantum dots has varied from 1.35 eV to 0.88 eV as calculated by Tauc plot. The observed values of bandgap indicate quantum confinement in two regimes-weak and strong confinement regimes. The results show that quantum confinement depends on both the size and composition of Ag2SexS1-x quantum dots. The alloying of Se to Ag2S has been confirmed using the Raman spectroscopy. These alloyed quantum dots might be reasonable for catching solar energy particularly from visible to NIR regime.
关键词： Alloyed Quantum Dots,Solar Energy,Quantum Confinement,Optical Band Gap
更新于2025-09-12 10:27:22
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Performance evaluation of composition graded layer of aSi1-xGex: H in n+aSi:H/i-aSi:H/p+aSi1-xGex:H graded band gap single junction solar cells
摘要： The work investigates the role of composition grading of amorphous silicon germanium alloy on single junction graded band gap amorphous silicon solar cells, for the first time. The fabrication and optical characterization of composition graded aSi1-xGex: H alloy by varying the gas flow rate of germane (GeH4) are presented. We propose the composition graded p+aSi1-xGex: H layer to be considered as one of the active layers in amorphous silicon based solar cells. The principle of operation of the solar cell is illustrated with the energy band diagram of proposed n+aSi:H/i-aSi:H/p+aSi1-xGex:H solar cell structure. Further, the behavior of the structure is evaluated through simulation in terms of proposed layer thickness variation and temperature variation. It is observed that the proposed structure is capable of delivering an open circuit voltage (V oc), short circuit current density (Jsc), Fill Factor (FF) and conversion efficiency (g) of 1.1 V, 15.56 mA/cm2, 0.885 and 15.19% respectively, which is at par with any other single junction amorphous silicon solar cells. The cell performance parameters were compared with related state of the art as well as our previous works. The performance parameters of proposed structure show that it is better to use a single composition graded layer instead of using a number of non-graded composition layers in photovoltaic structures, which reduces complexity and cost of fabrication.
关键词： Internal Quantum Efficiency,Optical band gap,Germane flow rate,Conversion efficiency,Composition grading,PECVD
更新于2025-09-12 10:27:22
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Effect of deep UV laser treatment on silicon-doped Tin oxide thin film
摘要： In this paper, the effect of deep ultraviolet (UV) laser on physical and electrical properties of amorphous Silicon‐doped tin oxide (amorphous Si‐Sn‐O, a‐STO) thin films were studied. Surface morphology, thickness, crystallinity, and optical band gap of a‐STO thin films treated by laser were investigated. Results showed that the decrease of thickness and surface roughness of a‐STO thin films after deep UV laser treatment, and the films maintained an amorphous structure, which implied that the quality of a‐STO thin films were improved. The peak position of oxygen vacancy binding energy became lower; this is caused by an increase in oxygen vacancies resulting in a decrease in coordination number. And the oxygen vacancy content of the a‐STO thin films was increased after deep UV laser treatment. In addition, the optical band gap of a‐STO films was broaden after the deep UV laser treatment. It exploits a new application of deep UV laser in oxide semiconductor.
关键词： oxygen vacancy,amorphous STO thin film,optical band gap,deep ultraviolet laser
更新于2025-09-12 10:27:22
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Fabrication and performance of dye sensitized solar cell based on spin coated ZnS nanoparticles
摘要： ZnSx nanoparticles (NPs) with different ratios of sulfur, x = 0.5, 1 and 2, were prepared by solvothermal technique. The structural analyses, based on XRD and FTIR, show that for sulfur content x = 0.5 two phases were formed ZnS and ZnO NPs with cubic and hexagonal structure, respectively. While for sulfur content x = 1 and 2 only ZnS NPs with cubic structure was observed. The crystallites size was study before and after annealing at 500 °C. SEM images show that the prepared samples have nanocrystalline nature. Absorbance spectrum was used to calculate the optical band gap of the powder samples dispersed in potassium hydroxide solution. All samples have direct optical band gap which was inversely proportional to the sulfur content. ZnS NPs were irradiated by different doses of γ-rays and the effect on optical band gap was studied. The resulting from solvothermal preparation technique was served as precursor solution to deposit ZnSx layers onto the fluorine-doped tin oxide coated glass substrates by spinning process. The deposited ZnS NPs layers were successfully used as photoelectrode materials in dye-sensitized solar cells and the I–V characteristics were measured under illumination and in dark. An improvement in the efficiency was observed after annealing the ZnSx layers, x = 0.5 and 1, photoelectrode materials.
关键词： Dye-sensitized solar cells,Solvothermal technique,ZnS nanoparticles,γ-irradiation,Optical band gap
更新于2025-09-12 10:27:22
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Interaction of Graphene Quantum Dots with Oligothiophene: A Comprehensive Theoretical Study
摘要： Graphene/polythiophene composites are widely used in a variety of optoelectronic devices and applications, e.g., as electrode materials in capacitors and solar cells, but the detailed molecular-level relationship between their structural and electronic properties is not well understood. We present a density functional theory study of these composites using model systems consisting of graphene nanosheets and nanoribbons sandwiched between oligothiophenes (up to 13 monomers in length). These systems are investigated by computing optical band gaps, UV-vis spectra, densities of states, and by analyzing noncovalent interactions in terms of the reduced density gradient. Frontier molecular orbital analysis reveals a significant decrease in the optical band gap upon increasing the concentration of graphene, which can be tuned by adjusting the proportion of graphene using larger nanoribbons. This finding has implications for device design in these materials.
关键词： UV-vis Spectra,Composites,Optical Band Gap,Graphene,Noncovalent Interactions,Density Functional Theory,Polythiophene
更新于2025-09-12 10:27:22