Optical Gap Research Articles

Optimisation, dielectric properties, and antibacterial efficacy of copper-grafted MgO nanoparticles synthesized via sol-gel method

This is the first study to optimize magnesium oxide nanoparticles by grafting copper as an effective antibacterial against prevalent pathogenic microorganisms, which were synthesized by sol-gel method with a particle size of 11–17 nm. At a preparation temperature of 70 °C, copper was added at rates of 2.5 wt%, 5 wt%, 7.5 wt% and 10 wt%. The particles were heated at 600 °C. Nanoparticles were analyzed using XRD, FTIR, UV–Vis spectrum, Raman, TGA-DTA, SEM, EDX, zeta potential and TEM. XRD study revealed the crystal structure of the space group of MgO nanoparticles is cubic. Optical measurements yielded optical gap values falling within the range of 2.35 eV, which was reduced to 2.20 eV. The presence of the copper dopants in the MgO host lattice was confirmed by FTIR analysis. It reveals the existence of Mg-O-Cu, Mg-O, and Mg-O-Mg bonds. Additionally, the dielectric and electrical characterization of MgO was conducted using complex impedance spectroscopy over a frequency range of 10–106 Hz and conductivity measurements across a temperature range of 60–380 °C. The real and imaginary parts of the dielectric constant showed both frequency-dependent and temperature-dependent behaviors. Notably, the variations observed in the imaginary component of the modulus and impedance at the maximum frequency indicates a relaxation process that is not of the Debye type, with calculated activation energies (Ea). Moreover, the samples were evaluated against various bacteria, including, -ve gram (Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa), and +ve gram (Staphylococcus aureus, and Streptococcus pneumonia) using two different techniques. Studies have shown that copper-containing samples exhibit resistance to these bacteria. These findings suggest that the samples have potential as useful biomaterials in nanobiotechnology.

Effect of Laser Irradiation with 532 nm Wavelength on The Optical Properties of PVA/MR Solutions

Background: This work aims to study the impact of 532 nm laser irradiating on the optical properties of the Polyvinyl alcohol/ Methyl Red (PVA/MR) solution before and after laser irradiation 32mW with various times (0, 20, 30 and 40) minutes. Materials and Methods: The polymer (PVA) powder 500 mg was dissolved in 50 ml distilled water at temperature 80 ˚C and the methyl red (MR) 30 mg was dissolved in 10 ml at temperature 80 ˚C using solution dilution formula . A semiconductor laser with a wavelength of 532 nanometers was used to irradiate the solution. Results: The absorbance, reflectance, and transmittance spectrum of solution prior to and following laser irradiation were recorded. Then, the optical constants and energy gap were calculated. Conclusions: The irradiation with the 532nm laser leads to a break of the bonds (From the absorbance spectrum, it decreases as the irradiation time increases. This indicates the breaking of bonds.) that results in an increase in the transmittance spectrum, and the energy gap.

Synthesis of Cu-SnO<sub>3</sub> NCs by Photo Irradiation Method for Removal Tartrazine Dye Yellow in Aqueous Solutions

Background: Copper tin oxide (Cu-SnO3) is a cheap and easily accessible tunable that has a 2.5-5 eV bandgap. It is a desirable semi-conductor because of these components for a number of applications, including transparent conducting oxides, transistors, solar cells and photocatalytic. Objective: The aim of this research is to increase the rate of yellow dye removal percentage efficiency by using Photo Irradiation Method that rate was determined between (59 to 76) % by the simple chemical method. Methods: Photo irradiation method used to synthesis Cu-SnO3 from precursor materials, the solution is irradiated by photocell for 30min with cooling (5°C) then drop sodium hydroxide (4 g in 100 ml) then washed, isolated by centrifugation for 20 minutes, grinding the dried powder and calcinated at (450 °C). Results: The crystallite size and the crystal structure of Cu-SnO3 NPs are (43-8.2) nm with a tetragonal structure. Field Emission-Scanning Electron Microscopy (FESEM) results displayed the formation of spherical and semispherical and an average size of (35.97 - 74.43) nm. The optical energy gap value (Eg) is 5 eV. It is clear from the disappearance of tartrazine’s yellow hue in an aqueous solution that the combination was shaken at 298 K and 185 rpm. Conclusions: Prove that the removal percentage process by a photo-irradiation method is more effective than other used methods.

Structural, optical, and shielding investigation of PVA/Te composite for technological applications

Using the casting process, polymeric films made of polyvinyl alcohol (PVA) including varying percentages of Te were created to form PVA/Te composite at doping concentrations of Te (0, 4.76, 13.04, 20 wt %), which denoted as PT1, PT2, PT3 and PT4 respectively. XRD results show semicrystalline nature in PT1 and PT2 however with further increasing of Te contents, a nano-crystallite Te appeared in PT3 and PT4. The absorption spectrum confirms that PT3 film is a good option to be used in UV-shielding. PT4 film shows an abrupt rise in absorption coefficient at 0.5 eV, 1.5 eV and UV regions, hence this qualifies this sample for various optical applications. The optical energy gap of the films varies between 4.94 eV and 3.32 eV for the indirect transitions and between 5.3 eV and 4.5 eV for the direct transitions, the PT4 film has the lowest values of both direct and indirect energy gaps. Several methods were used to measure the average refractive index nav value. Furthermore, the nonlinear refractive index (n2) was estimated. PT4 possesses the highest value of both nav and n2. Furthermore, the radiation shielding coefficients have been estimated according to the Phy-X/PSD online software. The sample with the highest Te concentration, PT4, has the best radiation shielding between the films under investigation. The investigated polymer with high Te weight percentage is an optical system that can be used for solar cells, optoelectronics, electronics, nonlinear optics, optical filters and for radiation shielding.

Self-biased photoelectrochemical photodetector based on liquid phase exfoliated SnSe nanosheets

The present article involves a liquid phase exfoliation technique to synthesize SnSe nanosheets. These nanosheets are deposited on an ITO glass substrate to make a thin film via an electrophoretic deposition (EPD) technique. Through the use of energy-dispersive X-ray analysis (EDAX), the cleanliness and chemical compositions of the film are examined. The surface topography of the deposited film is carried out by scanning electron microscopy (SEM). The orthorhombic crystal structure of SnSe thin film is verified by X-ray diffraction (XRD) analysis. The optical gap energy and absorbance profiles also exhibit a morphology-dependent response, as measured by ultraviolet–visible (UV–vis) spectroscopy. The Photoresponse performance of SnSe thin film-based PEC-type photodetector was carried out under illumination of poly and monochromatic wavelengths. SnSe nanosheet-based photodetector showed a maximum photocurrent of 14.50 μA under polychromatic light of intensity 100 mW/cm2, at zero bias. This study demonstrates how the Requirement for TMC semiconductors in optoelectronic devices increases due to their exceptional photoresponse performance.

Structural Expansion and Enhanced Photocurrent Conversion of Selenido Stannates with Cu+ Ions.

As a means of tuning the electronic properties of tin-chalcogenide-based compounds, we present a strategy for the compositional and structural expansion of selenido stannate frameworks under mild conditions by introducing Cu+ ions into binary anionic Sn/Se aggregates in ionothermal reactions. The variable coordination modes of Cu+-contrasting with tetrahedral {SnSe4} or trigonal bipyramidal {SnSe5} units-and corresponding expansion toward ternary Cu/Sn/Se substructures helped to add another degree of freedom to the nanoarchitectures. As desired, the variation of the structural features was accompanied by concomitant changes of the physical properties. Upon treatment of alkali metal salts of the [SnSe4]4- anion at slightly elevated temperatures (120 or 150 °C) in ionic liquids, we isolated a series of compounds comprising ternary or quaternary cluster molecules or networks of cluster units, (C2C2Im)9Li[Cu10Sn6Se22] (1), (C2C2Im)4[Cu8Sn6Se18] (2), (C2C1Im)3[Cu5Sn3Se10] (3), and (C2C2Im)5[Cu8Sn6Se18F]·(C2C2Im)[BF4] (4; C2C2Im = 1,3-diethyl-imidazolium, C2C1Im = 1-ethyl-3-methyl-imidazolium), which were investigated in terms of their optical gaps and photocurrent conversion properties. As illustrated by the synthesis and characterization of an additional salt that does not include Cu+, {(C2C2Im)2[Sn3Se7]}4·{(C2C2Im)[BF4]}2 (5), the significant role of Cu+ in this system was shown to be 3-fold: (a) structural expansion, (b) narrowing of the optical gap, and (c) photocurrent enhancement. By this three-in-one effect, the work offers an in-depth understanding of chalcogenido metalate chemistry with atomic precision.

In-situ ‘X’ doped ‘GCN’ photocatalyst enables selective aldehyde synthesis via photo-oxidation of benzyl alcohol under ambient conditions

Photo-oxidative selective conversion of benzyl alcohols using graphitic carbon nitride (GCN) is a sustainable strategy for conventional metal-doped heterogeneous catalytic oxidation systems. Non-metal doped graphitic carbon nitride (a subclass of GCN) enhances its properties as an efficient photocatalyst for oxidation. These heteroatom non-metal dopants alter the optical energy gap and chemical and electronic properties of GCN, making it ideal for creating cost-effective, practical utility. So, herein, we designed heteroatoms (X = B, S, C) doped GCN photocatalysts derived from melamine (M) with different heteroatom ingredients and compared their activity in detail. Among these, the photo-oxidation of benzyl alcohol under blue LED by S-doped GCN (S-GCN) photocatalyst exhibits utmost higher photocatalytic activity than other heteroatoms doped GCN photocatalyst due to suitable band gap and slow photoinduced charge carriers recombination. The suitable energy gap with higher chemical stability is accountable for the substantial increase in the photocatalytic efficiency of S-GCN in the solar light responsive integrating reactions of oxidation of benzyl alcohol in aerobic conditions. Attaining an exceptional >99 % selectivity towards benzaldehyde (up to 5 cycles without significant loss of activity) marks a remarkable milestone. This opens up new possibilities for using these simple non-metal-doped photocatalysts in fine chemical synthesis.

Coloring Tetrahedral Semiconductors: Synthesis and Photoluminescence Enhancement of Ternary II-III2-VI4 Colloidal Nanocrystals.

Ternary tetrahedral II-III2-VI4 semiconductors, where II is Zn or Cd, III In or Ga, and VI S, Se, or Te, are of interest in UV radiation detectors in medicine and space physics as well as CO2 photoreduction under visible light. We synthesize colloidal II-III2-VI4 semiconductor nanocrystals from readily available precursors and ascertain their ternary nature by structural and spectroscopic methods, including 77Se solid-state NMR spectroscopy. The pyramidally shaped nanocrystals range between 2 and 12 nm and exhibit optical gaps of 2-3.9 eV. In the presence of excess anions on the particle surface, treatment with Lewis acidic, Z-type ligands results in better passivation and enhanced photoluminescence. Electronic structure calculations reveal the most stable, lowest energy polymorphs and coloring patterns. This work will pave the way toward more environmentally friendly, ternary semiconductors for optoelectronics and electrocatalysis.

Investigation of thermally induced surface composition and morphology variation of magnetron sputtered Sb2Se3 absorber layer for thin film solar cells

One of the most promising semiconductor materials for the development of sustainable thin-film solar cell technology is antimony selenide (Sb2Se3). Its excellent optical and electrical properties have drawn attention lately for potential application in thin-film solar cells. In this study, Sb2Se3 films deposited using the direct current (DC) magnetron sputtering technique have been subjected to a post-annealing process without an extra selenium supply at temperatures between 150 and 450 °C. Without an extra selenium supply, the impact of post-annealing temperature on the surface composition as well as the physical properties of the fabricated films was investigated. The overall evaluations revealed that the post-annealing temperature is highly efficient in altering the physical properties of the Sb2Se3 absorber thin films. We further observed that the post-annealing process improved the crystallization and the heat treatment temperature quite affected preferential orientation. The surface morphology of films exhibited structural deformation at high post-annealing temperatures (> 350 °C). According to optical and electrical characterizations, respectively, the optical energy gap and the resistivity of Sb2Se3 films reduced with an increment in the post-annealing temperature. Based on the XPS result, the variation in temperature of post-annealing led to a change in the surface composition of the films. The findings on the growth of Sb2Se3 thin films indicate the existence of an intermediate growth temperature that permits the growth of Sb2Se3 films to be optimized. The study’s conclusions can serve as a guide to the growth of Sb2Se3 thin films with the desired crystallinity, surface morphology, and composition for thin film solar cell applications.

Optical properties of 4H-SiC and 6H-SiC from infrared to vacuum ultraviolet spectral range ellipsometry (0.05–8.5 eV)

Complex dielectric function (ɛ = ɛ1 + iɛ2) spectra are obtained from reflection mode spectroscopic ellipsometry and unpolarized transmittance measurements for 4H and 6H stacking sequence silicon carbide (SiC) nitrogen-doped single crystals from the infrared (IR) to vacuum ultraviolet (VUV) spectral range. A single parametric model describing ɛ predominately for the ordinary directions is developed over the 0.05–8.5 eV spectral range from analysis of (0001)-oriented back side roughened 4H-SiC and 6H-SiC single crystals with some contribution from the extraordinary direction of 6H-SiC in the IR region. Indirect bandgaps for 4H-SiC and 6H-SiC are found to be 3.30 and 3.03 eV, respectively, and the corresponding direct optical gaps are at 4.46 and 4.42 eV. A model describing the optical response in the IR spectral range is created using a Drude expression and either transverse optical (TO) and longitudinal optical (LO) (TOLO) or Lorentz oscillator models. Free carrier concentration (N) is optically measured to be 3.7 × 1018 and 3.3 × 1018 cm−3 using TOLO and Lorentz oscillator models, respectively, and the corresponding carrier mobility (μ) is 34 and 39 cm2/V s for 4H-SiC. Under the same assumption for 6H-SiC, N is measured to 8 × 1018 cm−3 using either TOLO or Lorentz oscillator models and μ is 9 and 10 cm2/V s using the TOLO and Lorentz oscillator models, respectively, in the ordinary direction and 5 cm2/V s in the extraordinary direction using either model. For 4H-SiC, using the TOLO oscillator model, TO and LO phonon modes are measured at 797.7 and 992.1 cm−1, respectively, and corresponding modes are found at same locations using the Lorentz oscillator model. In 6H-SiC, using the TOLO model, TO modes in ordinary and extraordinary directions are found at 797.7 and 789.7 cm−1, and corresponding modes are at 796.9 and 788.9 cm−1 using the Lorentz oscillator model. The LO modes using the TOLO model are found at 992 and 984 cm−1 in the ordinary and extraordinary directions, respectively, and the same modes in the corresponding direction using the Lorentz oscillator model are located at 975.9 and 967.9 cm−1.

Growth of Ba2CoWO6 single crystals and their magnetic, thermodynamic and electronic properties

This study explores the bulk crystal growth, structural characterization, and physical property measurements of the cubic double perovskite Ba2CoWO6(BCWO). In BCWO, Co2+ions form a face-centred cubic lattice with non-distorted cobalt octahedra. The compound exhibits long-range antiferromagnetic order belowTN= 14 K. Magnetization data indicated a slight anisotropy along with a spin-flop transition at 10 kOe, a saturation field of 310 kOe and an ordered moment of 2.17µB atT= 1.6 K. Heat capacity measurements indicate an effectivej= 1/2 ground state configuration, resulting from the combined effects of the crystal electric field and spin-orbit interaction. Surface photovoltage analysis reveals two optical gaps in the UV-Visible region, suggesting potential applications in photocatalysis and photovoltaics. The magnetic and optical properties highlight the significant role of orbital contributions within BCWO, indicating various other potential applications.

High efficiency in blue TADF OLED using favorable horizontal oriented host

An appropriate host featuring a wide band gap (Eg) and high triplet energy (T1) is crucial for facilitating highly efficient blue-light emitting devices. In this study, 4Ac26CzBz, a new host comprising acridan and carbazole moieties linked to a benzimidazole core, has been synthesized and characterized. Notedly, 4Ac26CzBz exhibits a wide optical gap (Eg) and high triplet energy (T1) of 3.3 and 3.0 eV, respectively, and has been proven a suitable host for blue thermally activated delayed fluorescence (TADF) OLED. By adopting 4TCzBN as a blue-light dopant, a remarkably high device external quantum efficiency of 35.8 % (59.8 cd/A and 62.8 lm/W) and a low turn-on voltage (<3 eV) have been demonstrated, with significant suppression of the efficiency roll-off, maintaining a high efficiency of 29.7 % as luminance at 1000 cd/m2. This excellent performance is deduced from the host’s ambipolar carrier transporting properties, which refer to its ability to transport both electrons and holes effectively, high photoluminescence quantum yield (PLQY) of 98.6 %, and highly horizontal orientation of transition dipole, as determined through diverse analytical measurements. The good material properties of 4Ac26CzBz and the high OLED performance reveal its potential for the next generation’s advanced display and lighting applications.

Enhancing plastic scintillator performance through advanced injection molding techniques

The production of plastic scintillators with superior optical properties, including high light yield and optimal emission spectra, plays a pivotal role in facilitating their extensive applicability across various domains. In addition, ensuring robust radiation hardness is essential for these scintillators to serve diverse purposes effectively. Given the significant impact of the optical gap on the optical characteristics and radiation resistance of scintillator products, we embarked on optimizing the injection molding technique, focusing on this critical parameter as part of the plastic scintillator fabrication process. Our findings indicate that the injection molding technique not only accelerates the fabrication process, but also yields products with comparable light yield and improved radiation hardness, outperforming samples produced by traditional thermal polymerization. These outcomes not only offer valuable insights and guidance for the streamlined production of high-quality plastic scintillators but also signify a notable advancement in this specialized field of study.

Investigation of Optical Properties of Polymeric Composite (PVA/PVP) Doped by Potassium Chromate

The practical out comes of the present study involves preparation of [Poly(vinyl) alcohol (PVA)]/[ pyrrolidone (PVP)] (50:25 wt%) composites doped by Potassium Chromate (K2CrO4) purity of 99% with different volume concentration (1.6% up to 7.7%) by simple solution casting method. The optical properties of the films were verified using UV-Vis-NIR spectroscopic analysis. The optical constants such as absorption coefficient, refractive index,Extinction coefficient real and imaginary parts of dielectric constant have been investigated, results show that the optical constants are affected by concentration of Potassium Chromate addition in the (PVA:PVP) blend . The optical gap decreased from 3.5 eV for pure (PVA:PVP) polymer blend to 2.5 eV for [(PVA:PVP)/ Potassium Chromate 7.7 wt%] while the refractive index increased from 2.43 to 2.74 depended on Potassium Chromate additive.Hybrid polymeric composites of Potassium Chromate additive in (PVA:PVP) can be considered as a promising material for different electronic application.

A Dibenzo[g,p]chrysene‐Based Organic Semiconductor with Small Exciton Binding Energy via Molecular Aggregation

AbstractExciton binding energy (Eb) is understood as the energy required to dissociate an exciton in free‐charge carriers, and is known to be an important parameter in determining the performance of organic opto‐electronic devices. However, the development of a molecular design to achieve a small level of Eb in the solid state continues to lag behind. Here, to investigate the relationship between aggregation and Eb, star‐shaped π‐conjugated compounds DBC‐RD and TPE‐RD were developed using dibenzo[g,p]chrysene (DBC) and tetraphenylethylene (TPE). Theoretical calculations and physical measurements in solution showed no apparent differences between DBC‐RD and TPE‐RD, indicating that these molecules possess similar properties on a single‐molecule level. By contrast, pristine films incorporating these molecules showed significantly different levels of electron affinity, ionization potential, and optical gap. Also, DBC‐RD had a smaller Eb value of 0.24 eV compared with that of TPE‐RD (0.42 eV). However, these molecules showed similar Eb values under dispersed conditions, which suggested that the decreased Eb of DBC‐RD in pristine film is induced by molecular aggregation. By comparison with TPE‐RD, DBC‐RD showed superior performances in single‐component organic solar cells and organic photocatalysts. These results indicate that a molecular design suitable for aggregation is important to decrease the Eb in films.

A Dibenzo[g,p]chrysene-Based Organic Semiconductor with Small Exciton Binding Energy via Molecular Aggregation.

Exciton binding energy (Eb) is understood as the energy required to dissociate an exciton in free-charge carriers, and is known to be an important parameter in determining the performance of organic opto-electronic devices. However, the development of a molecular design to achieve a small level of Eb in the solid state continues to lag behind. Here, to investigate the relationship between aggregation and Eb, star-shaped π-conjugated compounds DBC-RD and TPE-RD were developed using dibenzo[g,p]chrysene (DBC) and tetraphenylethylene (TPE). Theoretical calculations and physical measurements in solution showed no apparent differences between DBC-RD and TPE-RD, indicating that these molecules possess similar properties on a single-molecule level. By contrast, pristine films incorporating these molecules showed significantly different levels of electron affinity, ionization potential, and optical gap. Also, DBC-RD had a smaller Eb value of 0.24 eV compared with that of TPE-RD (0.42 eV). However, these molecules showed similar Eb values under dispersed conditions, which suggested that the decreased Eb of DBC-RD in pristine film is induced by molecular aggregation. By comparison with TPE-RD, DBC-RD showed superior performances in single-component organic solar cells and organic photocatalysts. These results indicate that a molecular design suitable for aggregation is important to decrease the Eb in films.

Emergence of defects-mediated diluted ferromagnetic semiconductor (ZnS: La3+) Quantum Dots: A versatile platform for optoelectronic and spintronic applications

For the first time, La3+ ions incorporated into semiconductor Zinc Sulfide-Quantum Dots (ZnS-QDs), Zn1-xLaxS, were effectively produced via a straightforward co-precipitation approach, with diverse La ratios (0.00 ≤ x ≤ 0.15 at%). The phase analysis of the acquired QDs, conducted through Raman analysis and X-ray diffractometer (XRD), revealed a singular cubic ZnS structure, devoid of any impurities. Morphology studies by HR-TEM showed a nearly spherical particle with a size of approximately 6.4 nm. X-ray photoelectron spectroscope (XPS) investigation disclosed the significant presence of sulfur vacancies, along with the existence of the trivalent oxidation state of lanthanum (La3+) within the ZnS structure. Optical absorbance studies exhibited that all QDs were positioned approximately at the absorption edges of around 270 nm (4.59 eV), surpassing the bulk ZnS energy gap of 337 nm (3.67 eV), harmonically with the quantum confinement effect. Additionally, a pronounced band gap narrowing was observed with increasing the doping level of La ions, on account of the presence of defects that result in the creation of localized states inside the ZnS band structure. The optical results indicated the capability to fine-tune the optical energy gap, dispersion parameters, and enhance the nonlinear optical parameters, which makes these QDs well-suited for use in optoelectronic devices. Furthermore, the photoluminescence (PL) spectra indicated that the La3+-doped ZnS nanocrystals (NCs) exhibited a wide visible emission band (blue emission) at room temperature, influenced by the La-doping concentration. Besides, the La3+-doped ZnS QDs elucidated ferromagnetic behavior at room temperature, which may be accredited to the vacancy-assisted bound magnetic polaron model. Exploring the intriguing magnetic features of ZnS: La3+ QDs could open avenues for developing innovative spintronic devices.

The comparative study of the empirical and DFT theoretical properties of ZnSnO3 perovskite nanoparticles

The composites of zinc tin oxide (ZTO) are lead-free materials, categorized as piezoelectric nanoparticles, and have a variety of multifunctional applications. These materials exhibit a lot of potential for a range of uses. Therefore, to prepare the aqueous solutions of ZnSnO3 and Zn2SnO4 and investigate the experimental structural and optical properties of ZTO materials, this work employed two different chemical reaction paths. ZTO materials are created via a straightforward chemical reaction process in which chemical route (I) combines tetravalent tin chloride with divalent zinc chloride. ZTO materials are generated via the employment of divalent zinc chloride and divalent tin chloride in chemical route II. The structural characteristics and composition of the material were investigated using XRD analysis. The materials were discovered to have hexagonal perovskites and a cubic structure. Furthermore, examining the optical characteristics led to estimating the optical energy gap values (Eg = 3.6 and 3.9) eV for the hexagonal and cubic perovskite structures, respectively. The paper also compares experimental results with theoretical findings obtained with the Cambridge Serial Total Energy Package (CASTEP) software’s Density Function Theory (DFT) approximation. Theoretical and empirical results were closely analyzed and contrasted.

Structural, optical spectroscopic, and density functional theory calculations of squaraine dye for organic electronic applications

The structural, optical spectroscopic, and density functional theory calculations of 2,4-Bis[4-(N,N-diisobutylamino)−2,6-dihydroxyphenyl] squaraine dye (SQ) are promising investigations that can be useful in photochemical mechanisms explanation and in designing promising chemosensors. The nature of the bonds, the chemical composition of SQ, crystallographic structure, morphology, and quality characteristics were explored by FTIR, XRD, and SEM investigations. The crystallite size, the dislocation density, and the lattice strain were found to be 57.3 nm, 3.045 × 10−4 nm−2, and 3.065 × 10−3, respectively. The spectrum behavior of the absorbance and molar absorption coefficient spectra of SQ in DCM with three concentrations were analyzed to get some important optical properties of SQ dye. The determined optical gap transition equals Egapopt=1.81eV. Quantum chemical computations and optimized molecular geometries identified where electrophilic attacks are likely and analyzed the molecule’s electrostatic potential. Using DFT calculations at the B3LYP/6-31+G(d,p) level, the electronic structure of the squaraine molecule was confirmed, showing a HOMO–LUMO gap of 1.73 eV. MEP analysis indicated that the oxygen atoms are electron-rich, suggesting potential for hydrogen bonding and electrophilic interactions.

Structure and optical properties of ZnxCd1-xS and Cu:ZnxCd1-xS templated on DNA molecules

One-dimensional ZnxCd1−xS and Cu: Zn x Cd1−x S nanostructures were prepared using DNA as a template to promote growth along the molecular axis. The formation of homogeneously alloyed nanocrystals with cubic zinc blende-type structures was verified using x-ray diffraction and Raman spectroscopy. X-ray photoemission spectra revealed the presence of Cu(I) in the doped Cu: Zn x Cd1−x S nanocrystals. The effectiveness of the DNA template to direct the semiconductor growth in one dimension was demonstrated by AFM and TEM. The nanostructures displayed a granular morphology comprising nanoparticles with an average diameter of 14 nm composed of assemblies of smaller crystallites of 2.0 nm in size. Rope-like assemblies with an average diameter of 48 nm and extending in length to several hundred micrometres were obtained by evaporation-induced self-assembly. UV-Vis absorption and emission spectra indicated that the optical bandgaps (2.89–4.00eV) and photoluminescence peaks (608–819 nm) of the DNA-templated nanocrystals could be precisely controlled by modifying the molar ratios of their Zn/Cd precursors. Doping with Cu(I) gave an increase in photoluminescence intensity and a composition-independent red-shift of 0.23 eV. The preparation of DNA-templated Zn x Cd1−x S and Cu: Zn x Cd1−x S provides a simple, low-temperature route to aqueous dispersions of inorganic materials with controlled optical gap.