Single Oscillator Model Research Articles

TiO2/SWCNts: Linear and Nonlinear Optical Studies for Environmental Applications

A series of single-walled carbon nanotube/titanium dioxide (SWCNTs/TiO2) composites were prepared by the incorporation of various concentrations (0, 5, 10, 20 V.%) of SWCNTs in TiO2. The prepared solutions were successfully formed on silicon and quartz substrates using the sol–gel spin-coating approach at 600 °C in ambient air. The X-ray diffraction method was used to investigate the structure of the samples. The absorbance and transmittance data of the samples were measured using a UV–vis spectrophotometer. Through the analysis of these data, both the linear and nonlinear optical properties of the samples were examined. Wemple–DiDomenico’s single-oscillator model was used to calculate the single-oscillator energy and dispersion energy. Finally, all samples’ photocatalytic performance was studied by the photodegradation of methylene blue (MB) in an aqueous solution under UV irradiation. It is found that the photocatalytic efficiency increases when increasing the SWCNT content. This research offers a new perspective for the creation of new photocatalysts for environmental applications.

Green approach to synthesis polymer composites based on chitosan with desired linear and non-linear optical characteristics

The current study used sustainable and green approaches to convey polymer composites with desired optical properties. The extracted green tea dye (GTD) enriched with ligands was used to synthesize zinc metal complexes. Green chitosan biopolymer incorporated with green synthesized metal complex using casting technique was used to deliver polymer composites with improved optical properties. The FTIR-ATR was used to identify the functional groups of the GTD, pure CS, and functional groups surrounding the synthesized zinc metal complex. Distinguished ATR bands were observed in green tea dye spectra, such as OH, C = O, and NH functional groups ascribed to various polyphenols. The ATR bands of the zinc metal complex compared to GDT established that GDT is crucial to capturing zinc cations and producing the Zn2+-metal complex. The broadness of the bands observed in CS-based composites inserted with the Zn2+- metal complex confirms strong interaction among the components of polymer composites. The XRD achievements confirm that CS films with different Zn2+- metal complex concentrations transferred to an amorphous composite. The XRD pattern of composite films establishes that the zinc metal complex scarified the crystalline phases of chitosan. Linear optical properties such as absorption, refractive index (n), and optical dielectric parameters were improved. The absorption edge of the composite’s films shifted to lower photon energies. Various models were used to determine the optical band gap. The band gap drops from when chitosan is loaded with a 36% Zn2+-metal complex. The Spitzer-Fan method is used to get the dielectric constant, and the Drude Lorentz oscillator model was used to calculate vital optical parameters, including N/m*, τ, and µopt. The W-D single oscillator model was used to determine the Eo and Ed parameters. The values of optical moments (M−1 and M−3) were calculated with the help of the W-D model. The oscillator’s strength () and wavelength () were determined via the Sellmeier model using the linear refractive index. The first-order nonlinear ( ), second-order non-linear () and third-order nonlinear optical susceptibility () were determined for all the films.

Enhancement of Molecular Structural and Linear/Nonlinear Optical Features of Chitosan/Titanium Dioxide Nanocomposite Films for Food Packaging and Optoelectronic Applications

The current study aims to synthesize and characterize nanocomposite films of chitosan and titanium dioxide in terms of molecular structure, thermal and optical properties for use in food packaging and optoelectronic applications. The Fourier-transform infrared (FTIR) spectroscopy was used to study the interaction between the TiO2-NPs and chitosan and the analysis confirmed that TiO2-NPs interacted with chitosan and demonstrated good compatibility. Differential scanning calorimetry and thermogravimetric analysis revealed that increasing the concentration of TiO2-NPs improved the thermal stability of the nanocomposites. The linear optical properties in the UV-Vis range (200–800 nm) were measured spectrophotometrically. Below 400 nm, the transmittance spectra of the nanocomposites show decreased degrees of transparency, indicating their capacity to entirely block UV-light transmission. Tauc's model was used to identify the types of electronic transitions in the samples. The single-oscillator model was utilized to investigate the dispersion energy and parameters. Nonlinear optical properties were also investigated. UV-Vis in the region (360-410 nm), the analysis revealed that increasing the concentration of TiO2-NPs from 0 to 12 wt% reduced the absorption edge from 2.716 to 2.043 eV, decreased the direct (3.282 to 2.798 eV) and indirect (2.417 to 1.581 eV) energy band gaps, increased the Urbach energy from 0.692 to 1.295 eV, decreased the dispersion energy from 11.324 to 5.621 eV, decreased the single oscillator energy from 6.308 to 5.393 eV, and improved the other linear and nonlinear parameters. The findings support the usage of CS/TiO2 nanocomposite films in the packaging industry and a variety of optical applications.

Linear and Nonlinear Optical Characteristics of Basic Fuchsin-Doped Polyvinyl Alcohol Films for Flexible Optoelectronics

Abstract Polyvinyl alcohol (PVA) containing different levels of basic fuchsine (BF) was prepared using the solution casting method. Characterization via Fourier-transform infrared spectroscopy detailed changes in functional groups within the PVA/BF composites, indicates the hydrogen bonding between OH group of PVA and BF molecules. Optical investigations spanning the 190-2500 nm range demonstrated UV blocking properties in prepared PVA/BF composites (fromn 2.05 to 2.56 eV and from 4.08 to 6.32 eV). Moreover, the studies on optical band gap indicated a decrease with increased BF concentrations, reflecting altered electronic transitions within the prepared composites. The study also employed the single oscillator model provided by Wemple-DiDomenico to elucidate refractive index variations. After incorporating BF dye into the PVA polymer, the values of the dielectric constant as the frequency approaches infinity (ε∞), the dielectric constant of lattice (εL), dispersion energy (Ed), and oscillator energy (Eo) in PVA/BF composite samples showed an increase. Moreover, the nonlinear optical properties, including optical susceptibility and nonlinear refractive index were investigated and discussed. These findings underscore the versatility of PVA doped with BF for various applications including optical filters, and solar cell devices.

Refractive index of CdTe1-xSex thin films estimated by Swanepoel's method

CdTe1-xSex thin films were deposited on a quartz and silicon substrate using the method of high-frequency magnetron sputtering. The chemical composition analysis and crystal structure refinement were examined using X-ray fluorescence spectroscopy and X-ray diffraction data. CdTe1-xSex thin films with x < 0.7 are crystallized in hexagonal structure (structure type – ZnO, space group P63mc (No. 186)) and in cubic structure (structure type – ZnS, space group F-43m (No. 216)) with x < 0.35. Unit-cell parameters decrease with increasing Se content in CdTe1-xSex thin films. The values of the optical band gaps for CdTe1-xSex thin films were estimated using the Tauc plot and from the maximum position of the first derivative of the transmittance dT/dλ. The study of optical functions is performed on the basis of the transmission spectrum measured experimentally using the Swanepoel's method. The spectral behavior of the optical functions, such as refractive index and real part of dielectric function is established. The dispersion of the refractive index is discussed in terms of the Wemple and Di Domenico single oscillator model.

Synthesis, spectral analysis, and DFT studies of the novel pyrano[3,2-c] quinoline-based 1,3,4-thiadiazole for enhanced solar cell performance

In this study, we synthesized a novel compound, 3-(5-amino-1,3,4-thiadiazol-2-yl)-6-ethyl-4-hydroxy-2H-pyrano[3,2-c]quinoline-2,5(6H)-dione (ATEHPQ), through a condensation reaction between 6-ethyl-4-hydroxy-2,5-dioxo-5,6-dihydro-2H-pyrano [3,2-c]quinoline-3-carboxaldehyde and thiosemicarbazide, followed by oxidative cyclization. We characterized ATEHPQ using elemental analysis, IR, 1H and 13C NMR spectroscopy, and mass spectrometry. Density Functional Theory (DFT) calculations with the B3LYP/6–311++G(d,p) basis set were employed to optimize the molecular geometry and analyze global reactivity descriptors, including HOMO-LUMO energies. The Molecular Electrostatic Potential (MEP) map was used to identify reactive sites, and drug-likeness studies indicated potential pharmaceutical applications. Notably, ATEHPQ showed a higher first hyperpolarizability (βtot) compared to urea, suggesting its suitability for nonlinear optical applications. We also determined the Miller indices for ATEHPQ's preferred orientations using a specialized program. Williamson–Hall analysis revealed an average crystal size of 26.08 nm and a lattice strain of 6.3 × 10−3. The thin films exhibited three distinct absorption peaks at 2.8, 3.41, and 4.21 eV, with a direct energy gap of 2.43 eV. Dispersion parameters from the single oscillator model provided oscillator and dispersion energies of 3.12 eV and 14.21 eV, respectively, with a high-frequency dielectric constant of 4.71. The ATEHPQ thin films, when combined with n-Si, demonstrated significant improvements in photovoltaic performance: the open-circuit voltage (Voc) rose from 0.13 V to 0.521 V, the short-circuit current (Isc) increased from 0.253 mA to 2.94 mA, the fill factor (FF) improved from 0.238 to 0.33, and the efficiency (η) grew from 0.71 % to 4.64 % with increased illumination intensity. These results highlight the excellent photovoltaic and photodetection capabilities of ATEHPQ thin films, underscoring their potential for advanced optoelectronic and solar cell applications.

Spectroscopic study of wemple-didomenico empirical formula and taucs model to determine the optical band gap of dye-doped polymer based on chitosan: Common poppy dye as a novel approach to reduce the optical band gap of biopolymer

This study investigates the effect of a natural dye extracted from common poppy (Papaver rhoeas) waste flowers on the optical properties of chitosan (CS) films. The extraction of natural dyes from waste flowers can be considered a new field for research in green chemistry. CS films are flexible and biodegradable but have low optical activity and band gap, limiting their applications in optical devices. The doped CS polymer with different concentrations of Papaver rhoeas dye exhibited enhanced optical properties. Also, 30 % glycerol was added as a plasticizer to omit film brittleness. The FTIR examinations is helpful to propose a mechanism that explains the interaction of the dye with the host polymer. The UV–vis spectroscopic examination establish that the optical characteristics of the films can be modified by adjusting the dye concentration. Furthermore, optical absorption properties are described using the Tauc non-direct transition model, revealing an approximate optical band gap of 1.64 eV. This band gap defines the energy required for electron transitions, elucidating the material’s electronic characteristics. The extinction coefficient (k) and refractive index (n) of the CS-doped films’ shows a dispersion behavior at visible regions of EM radiation. The Wemple-DiDomenico single oscillator model was used to investigate the n dispersion and determine the oscillator energy equivalent to the optical band gap. Additionally, calculations have been performed on optical dielectric properties and optical conductivity. The Urbach energy was measured and used to detect the structure of the films. The findings underscore the potential applications of these natural dye-doped CS films in eco-friendly materials and optical devices.

Insights and perspectives on PVDF/MgO NCs films: Structural and optical properties for optoelectronic device applications

In the current investigation, pure polyvinylidene fluoride (PVDF) and PVDF-MgO nanocomposite (NC) thin films are fabricated via solvent casting method using PVDF as a polymer matrix with different proportions of magnesium oxide (MgO) (0.5–2 wt%). The structural, morphological and optical properties of the prepared polymer NCs are studied by using XRD, FTIR, SEM, Raman and UV–Vis spectroscopy techniques. The α and β phases are detected in XRD measurements. MgO powder peaks are in good agreement with the reported literatures. The average crystallite size, lattice strain, and dislocation density of the prepared thin films are estimted by using Williamson-Hall (W-H) plot. SEM micrographs reveals the fluorine-containing carbon chain network that forms the spherulite and fiber-like structure in the PVDF/MgO NCs films. The Raman and FTIR spectra of PVDF/MgO and pure PVDF films are also evaluated. UV–Vis spectroscopy is used to examine the absorbance, transmittance, and reflectance spectra of pure PVDF and PVDF/MgO NCs thin films. The dipole polarization interaction causes the absorption coefficient, direct band gap, indirect band gap, optical activation energy, and skin depth of pure PVDF and PVDF/MgO thin films to decrease, whereas increasing the dielectric constant at high frequency value, refractive index, loss, optical conductivity, and dielectric constant per effective mass of NCs films. Optical dispersion parameters are estimated by the single oscillator model. The obtained results can be employed in the possible applications in supercapacitors. The method used for the preparation of thin films are inexpensive and eco-friendly.

Direct Calculations of the Dielectric and Optical Parameters of Some Compound Semiconductors: A Study Using the Lorentz Oscillator and Wemple-DiDomenico Models

The Lorentz single oscillator model is widely utilized to describe the electron-phonon interaction in solids. The use of this model to calculate the dielectric function and optical parameters of compound semiconductors represents a novel approach in materials science which may lead to develop new materials with tailored optical properties and consequently can offer vast applications in areas such as quantum computing and quantum information processing. This work presents direct calculations of the complex dielectric function and some optical parameters, such as refractive index, extinction coefficient, and reflectivity for some selected III-V and II-VI compound semiconductors using Lorentz oscillator model. The dielectric and optical dispersion parameters among the infrared and visible electromagnetic spectra follows the so-called Transmission-Absorption-Reflection-Transmission (TART) trend. The TART curve provides information about how a material interacts with light at different wavelengths, which is crucial for understanding and optimizing various optoelectronic devices. Moreover, dielectric loss functions such as loss tangent, surface energy loss function and volume energy loss function are investigated. The refractive index dispersion is analyzed using Wemple–DiDomenico single effective oscillator model and Sellmeier equation. The energy of the effective single oscillator (Eo) and the dispersion energy (Ed) are estimated.

Influence of Post-Annealing Treatment on Some Physical Properties of Cerium Oxide Thin Films Prepared by the Sol–Gel Method

In this study, thin films of Cerium Oxide CeO2 were fabricated using the sol–gel technique and deposited onto a glass substrate. The annealing process was carried out at various temperatures ranging from 200 to 600 °C to investigate the structural, morphological, and optical properties of the films and their interrelations. X-ray diffraction (XRD) patterns revealed the crystalline nature of the prepared films, with film quality exhibiting enhancement with increasing annealing temperature. The average crystallite size, dislocation density, microstrain, and lattice constant were determined from XRD patterns. Higher annealing temperatures were found to increase the crystallite size values from 4.71 to 15.33 nm and decrease the dislocation density and microstrain of the unit cell. Scanning electron microscope (SEM) images illustrated the uniformity of the films, presenting a spheroid shape. Optical properties such as transmittance, absorbance, reflectance, the direct band gap, extinction coefficients, the refractive index, and optical conductivity were assessed using optical measurements. The direct optical band gap of the CeO2 film was observed to decrease from 3.99 to 3.75 eV with increasing film thickness. Using the Wemple and DiDomenico (WDD) single-oscillator model, dispersion energy parameters were calculated based on the refractive index. The nonlinear optical properties of the CeO2 thin films were evaluated using these dispersion energy parameters. The improvement of optical parameters holds significance in standardizing CeO2 thin films for various optoelectronic applications.

Studies on ionic conductivity, linear and non-linear optical properties of ecofriendly methyl cellulose: sodium bromide based solid polymer blend electrolytes

Biopolymer electrolytes based on methyl cellulose (MC) and sodium bromide(NaBr) have been prepared through solvent casting technique. Both the concentrations of MC and NaBr are varied. The prepared biopolymer electrolytes have been subjected to AC impedance and UV-Vis spectroscopic techniques. The ionic conductivity reached a maximum value of 4.84 × 10−8 Scm−1 for 0.8 g of MC and 0.2 g of NaBr. UV studies revealed that low direct and indirect band gaps have been observed for the maximum ionic conducting sample. Other optical parameters, such as refractive index, extinction coefficient, skin depth, and optical conductivity, have been estimated. The single-oscillator energy (Eo ) and dispersion energy (Ed ) for all the prepared biopolymer electrolyte samples were calculated with the help of Wemple and DiDomenico single oscillator model. The higher-order non-linear susceptibility values were also calculated. Polymer electrolytes are found to be suitable for optical and electronic devices.

Optical characterization of high-quality spin-Coated PVA nanostructured films for photo-sensing application

In our investigation, we fabricated high-quality Polyvinyl Alcohol (PVA) films via spin coating on a variety of substrates, with a focus on their potential applications in diverse devices. Through comprehensive characterization techniques, including spectrophotometer measurements, we evaluated the nanostructure and quality of these films. Our analysis revealed a distinct energy gap of 1.74 eV and a significant 5.37 eV direct allowed optical transition, shedding light on the correlation between absorption coefficient and photon energy. Additionally, we meticulously calculated dispersion parameters using the Wemple-DiDomenico relation, obtaining values of 19.1 eV for dispersion energy and 9.48 eV for oscillator energy under the single oscillator model. These results provide further validation of the unique structural characteristics of PVA films. Importantly, our findings underscore the potential of these materials for advanced optoelectronic devices, particularly in the realm of photosensor applications.

Tailoring the optical properties of dye–polymer composite films based on polyvinyl alcohol doped with phenol red toward flexible optoelectronic applications

The composite films of polyvinyl alcohol (PVA) incorporating varying concentrations of phenol red (PR) dye were fabricated using the solution casting method. Structural characteristics of the prepared films were explored through XRD and FTIR spectroscopy analyses. The inclusion of PR dye within the PVA matrix induced cross-linking, enhancing the amorphous nature of the doped PVA samples, as evidenced by XRD patterns. In the presence of PR dopants, the FTIR peaks for PVA exhibited altered intensities and increased width, indicating physical interactions between the functional groups of PVA and PR dopants. The impact of PR additives on the optical properties of PVA was investigated across the spectral range of 190–2500 nm. The PVA/phenol red composite demonstrated enhanced UV blocking in the 190–400 nm wavelength range, rendering it suitable for applications such as UV notch filters, including laser blocking filters. The indirect and direct optical band-gaps of PVA polymer films were reduced from 5.20 eV and 5.78 eV to 4.30 eV and 5.28 eV, respectively, with an increase in the PR filling ratio from 0 wt% to 1.8 wt%. The dispersion region of the refractive index was analyzed using the single oscillator model (Wemple-DiDomenico). Calculation and discussion of values such as dispersion and oscillation energies (Ed and Eo), permittivity at infinite frequency (ε ∞), and lattice contribution to the dielectric function (ε L) of PVA/PR composite films were conducted. These advancements position PVA/PR composite films for potential applications in flexible optoelectronic devices, including light-emitting diodes and photodetectors.

Exploration of the optical characteristics in sol-gel synthesized europium-doped zinc oxide thin films for potential optoelectronic use: a comprehensive characterization approach

Abstract In this study, we present our findings on the spin coated pure Zinc-Oxide (ZnO) nanowire arrays and Europium doped ZnO (Eu3+: ZnO) nanostructure thin films. These arrays were grown on soda lime (silica) coated glass substrate. We conducted a comprehensive analysis of the structural and optical properties of the as-synthesized nanostructures. The characterization techniques included x-ray Diffraction, FESEM Analysis, Raman Spectroscopy, Photoluminescence and UV–vis Analysis. The XRD findings indicate the incorporation of Europium (Eu3+) into the ZnO crystalline lattice, potentially replacing Zn2+ ions. This doping with Europium (Eu3+) led to a reduction in crystalline size, as determined by Scherrer’s equation decreasing from 48 nm to 28 nm demonstrates a decrease in defects within the films. Raman Shift analysis revealed changes in the optical properties of films with inclusion of Europium in host matrix. Photoluminescence studies demonstrated a distinctive 5D0 to 7F2 transition arising from the Eu3+ ions, observed at approximately 612 nm. We have thoroughly examined the optical characteristics of both Europium-doped and pure ZnO thin films through a systematic study. The optical properties were assessed by analyzing the absorption spectra (220–600 nm) and transmission spectra within the wavelength range of 200 to 1200 nm. The film exhibited an impressive 80% transparency, particularly noteworthy for window layer application. The refractive index (n), extinction coefficient (k) and all other associated parameters were found to be impacted by the doping of Europium. The refractive index dispersion relation has been explored using a single oscillator model. Furthermore, the non-linear optical susceptibility (χ 3) and non-linear refractive index were computed using semi-empirical relationships based on the linear optical parameters. The Europium (Eu3+) doping in ZnO led to an increase in the χ 3 value elevating it from 4.07 × 10–1° to 5.91 × 10–1° e.s.u. These findings suggest that Europium-doped ZnO nanostructures have the potential to be a promising platform for the development of efficient multispectral light-emitting diodes (LED’s) and optical devices.

Investigation of Physical Properties of Nanostructured Selenium-Based Compound Semiconductors

The study of physical properties of compound semiconductors plays a vital role in the device fabrication point of view. Different investigations suggest that one can tune these properties by impurity dopants, irradiation techniques, adopting different synthesis techniques, etc. In this study, the physical properties of nanostructured thin films of Se–S compound were tuned by different Hg dopant concentrations. X-ray diffraction spectra clarify the preferred crystallite growth occurs in the cubic phase of the corresponding Bravi’s crystal system. The particle size calculated from Bragg’s reflection spectra by using Scherrer’s analytical formula illustrates an enhancement of crystallite size in highly concentrated Hg-doped sample. Similar consequences are found in surface morphological micrographs. The optical band gap reduced from 1.65[Formula: see text]eV to 1.54[Formula: see text]eV on increasing the doping concentration of Hg, according to the computed optical parameters using optical transmission spectra in the wavelength range 200–1100[Formula: see text]nm. The thin-film refractive index dispersion data fits well in accordance with the single oscillator model. Investigation of electrical properties tells that there is significant improvement in electrical conductivity in highly concentrated Hg-doped samples. Therefore, the apparent tuning as observed in the physical properties of the investigated material may have practical uses in industry for a variety of optoelectronic devices.

A study on vortex-induced vibration of a long flexible catenary cable in perpendicular flow

In this paper, a numerical model based on Euler-Bernoulli beam theory and a single van der Pol wake oscillator model is proposed to study the vortex-induced vibration of a long flexible catenary cable with a low mass ratio. The wake model uses only one oscillator to describe the in-line and cross-flow vibration with consideration of their nonlinear coupling. An experiment on a flexible cable model in perpendicular flow is carried out to validate the proposed numerical model. Numerical results and experimental measurements are compared on the vortex-induced vibration responses including the maximum amplitude, axial tension, and vibration frequency. A sensitivity analysis of the parameters used in the numerical model has been carried out. Numerical simulations by the proposed numerical model with properly selected parameters have demonstrated that the vibration frequency and the axial tension can be well predicted, and the variation of the vibration amplitudes can also be properly captured. The lock-in phenomena and the axial tension variation of the long flexible catenary cable in perpendicular flow have been carefully studied both numerically and experimentally.

Testing the physical properties stability of Zinc (8-hydroxyquinoline) thin films toward stable photodetection performance: Effect of annealing

In this study, the effect of thermal annealing on the structural and optical properties of thermally evaporated zinc (8-hydroxyquinoline) (ZnQ2) thin films is discussed in detail. Differential scanning calorimetry analysis revealed the thermal stability of the ZnQ2 powder up to 540 K. Fourier transform infrared spectrometer characterizations revealed the stability of the ZnQ2 molecular structure up to 423 K. The annealing effect on the surface morphology of the ZnQ2 films was tracked using the field emission scanning electron microscope (FE-SEM) technique, which revealed grain growth up to 423 K achieving the highest surface smoothness. Moreover, UV–Vis-NIR spectrophotometric measurements were used to examine how annealing affects the optical characteristics of the prepared films. The optical bandgap of ZnQ2 augmented when the annealing temperature increased to 373 K. The dispersion parameters were estimated from the analysis of the complex refractive index following the single oscillator model. The behavior of nonlinear optical susceptibility suggested the validity of utilizing ZnQ2 thin films in IR and UV optical switching applications and UV photodetection applications.

Spectroscopic investigation demonstrating the enhancement of the linear/nonlinear optical properties of PVA: BSA blend films

The aim of this study was to prepare novel blend films of poly(vinyl alcohol):bovine serum albumin at different concentrations (96:4, 92:8, 88:12, and 94:16 wt/w%) for use in optoelectronic applications. Linear optical parameters were determined from transmittance and reflectance spectra using spectroscopic data in the range 400–2500 nm. Absorption coefficient analysis gives the type of bandgap transition. The calculated values of absorption edge and optical bandgap energy were increased when the BSA content increased to 8 wt% and then decreased when BSA increased to 16 wt%. The values of Urbach energy and bandgap energy have opposite behavior to each other. Absorption and refraction indices and related parameters were calculated. The data showed significant variations that lead to improved optical parameters and confirm that photon-electron interactions in the films change. The Wemple-DiDomenico model was used to evaluate the dispersion energies and related parameters. The dispersion energy values increase from 3.412 to 12.206 eV, while the oscillator energy values decrease from 6.104 to 4.696 eV and then increase to 6.677 eV with increasing BSA content to 16 wt%. The Eo/(Eg)d ratio is found in the range 1.82–2.82 which may coincide with the prediction of a single oscillator model. Other important dielectric-optical parameters were discussed. Some nonlinear optical properties were also evaluated. Increasing the amount of BSA increased the nonlinear parameters which is beneficial for enhancing local polarization of the blend. All studied parameters are discussed and linked together. The results obtained from this study suggest that these prepared blends can be used in numerous optical applications.

Auger-limited minority carrier lifetime in GeSn/SiGeSn quantum well

A minority carrier lifetime of 2.7 ns is measured at 77 K for a GeSn/SiGeSn single quantum well using time-resolved photoluminescence, and subsequent analyses indicate that the lifetime is Auger-limited. The 77 K lifetime is evaluated as a function of stepwise dose of 63 MeV proton irradiation up to a fluence of 1.5 × 1012 p+/cm2 with no discernable reduction in the observed lifetime, which implies that the lifetime damage factor slope to 63 MeV proton irradiation is not greater than 2 × 10−5 cm2/s. Steady-state photoluminescence is used to evaluate the total luminescence output as a function of excitation, yielding a 2/3 power law slope consistent with Auger-limited recombination. The observed Auger-limited behavior is consistent with reports of high p-type background carrier concentration in these alloys. The temperature dependence of the steady-state photoluminescence spectra also provides the Einstein single oscillator model parameters for the ground state transition energy and Urbach energy of the GeSn quantum well.

PbS QDs and rGO-decorated PbS QDs induced optical properties variations on P3HT:PC61BM composite thin films

PbS QDs and PbS QDs decorated with reduced graphene (rGO) are prepared by hot-injection method using PbO and hexamethyldisilathiane (HMDS) as Pb and S sources, respectively. PbS QDs and PbS QDs:rGO are used as an addition to poly(3-hexylthiophene-2,5-diyl):phenyl-C61-butyric acid methyl ester (P3HT:PC61BM) composite. The effect of their addition on the morphological, topographical and optical properties of spin-coated P3HT:PC61BM thin films are investigated. These additions tune the films to be more homogenous and more flatness as investigated in terms of field scanning electron microscope. The topographical properties of the films are explored by atomic force microscope. The results show decreasing in the grain size and the surface roughness in P3HT:PbSQDs:PC61BM film compared to other composites films. The optical properties of the films are studied over the spectral range 200–2500 nm. On one hand, the absorption coefficient of different films is computed and the optical band gap of the films is found to decrease after addition of PbS QDs and PbS QDs:rGO. On the other hand, the refractive index of the films is explained according to the single-oscillator model to get the dispersion parameters. In addition, the lattice dielectric constant and the ratio of the free-carriers concertation to their effective mass are evaluated.