Values Of Optical Absorption Coefficient Research Articles

Rational analysis of hydrogen bonding interaction in phenazine, 2-hydroxynaphthalene (1:1) cocrystal: from molecular modeling to photophysical properties.

Organic cocrystals have a wide range of applications in the field of optics due to their photo responsive property. We present here a newly synthesized phenazine 2-hydroxynaphthalene (1:1) cocrystal, its structural and theoretical calculations which tend to the nonlinear optical property. In the crystal structure of the title cocrystal, the phenazine and 2-hydroxynaphthalene molecules from one- and two-dimensional supramolecular frameworks via O‒H…N hydrogen bonds and C‒H…N, C‒H…π interaction, respectively. The phenazine molecules from an infinite off-set stacking through π…π interactionin the three-dimensional molecular packing of the title cocrystal. The contribution of intermolecular interaction in the three-dimensional molecular packing and the interaction energy calculation is studied by the Hirshfeld surface analysis. The molecular geometry retrieved from the experimental X-ray diffraction analysis is in good agreement with the theoretically calculated parameters. Further, the molecular electrostatic potential (MEP) and frontier molecular orbital (FMO) analysis have been carried out to study the charge distribution and molecular reactive mechanism. Third-order nonlinear optical property of the cocrystals has been analyzed by Z-scan measurements. The determined nonlinear optical absorption coefficient value 6.442 × 10-05 (m/W) and the nonlinear refractive index value - 5.535 × 10-2 (m/W) suggest that the crystalline solid can be a good choice of potential nonlinear optical material. The crystal structures of phenazine 2-hydroxynaphthalene cocrystal was solved by direct methods procedure using SHELXS program and refined by full-matrix least square procedure on F2 using SHELXL-2018 program on Olex2 software. The computational calculation has been carried out using DFT/B3LYP quantum chemical function with triple zeta 6-311 + + basis set in the ground state molecular stability using Gaussian 09W program suite. The Hirshfeld surface analysis mapping, associated 2D fingerprint plot, and intermolecular molecular interaction energy calculations were carried out using CrystalExplorer (version 21.5) software.

Efficient visible-light-driven photocatalytic hydrogen evolution in novel type-II SnS2/Al2S2 van der Waals heterostructures

With the exacerbation of environmental pollution and the energy crisis, the development and design of environmentally friendly and efficient photocatalytic catalysts for water splitting with visible light have become particularly imperative. This study delves into the detailed investigation of the novel type-II van der Waals heterostructure of SnS2/Al2S2 utilizing first-principles calculation methods. By leveraging the advantages of indirect type-II band alignment and high carrier mobility, the efficient separation of electron-hole pairs is achieved, thereby facilitating enhanced participation of electrons and holes in photocatalytic reactions. Furthermore, the heterostructure manifests a peak optical absorption coefficient value of approximately 5.34×104 cm−1 in the visible light spectrum, accompanied by the occurrence of red-shifting, which fosters efficient absorption of visible light. It is noteworthy that under conditions of pH = 0–3.7, the heterojunction surpasses the redox potential of water splitting, concurrently displaying a substantial hydrogen evolution reaction (HER) and a high efficiency of converting sunlight to hydrogen (22.31 %). These results underscore the promising potential of the SnS2/Al2S2 heterostructure as a photocatalyst for water splitting, offering crucial theoretical support and practical guidance for the further advancement of hydrogen production via water splitting technology.

Photoresponse in sequentially stacked antimony selenide thin films

Antimony selenide (Sb2Se3), a binary semiconducting compound has widespread research attention due to its excellent optoelectronic properties in the visible region and usefulness in applications such as solar cells, photosensors and photoelectrodes. The presented study explores the thickness dependent photoresponse in Sb2Se3 thin films, prepared by reactive selenization of antimony films having thickness values of ∼938 nm and ∼1879 nm when stacked second time. Growth orientation along [001] direction was achieved through carefully optimized selenization conditions to enable favourable charge transport in anisotropic Sb2Se3. Predominant Sb2Se3 formation was inferred from x-ray diffraction, Raman spectroscopy, secondary electron microscopy and energy-dispersive X-ray analyses. High optical absorption coefficient values of about 1 × 105 cm−1 and 5.7 × 104 cm−1 were observed for ∼938 nm and ∼1879 nm thick Sb2Se3 thin films. Further, the optoelectronic properties were elucidated through current–voltage and transient photoresponse measurements under dark and illumination conditions. The measurements were done under zero and different bias voltages. Sb2Se3 films having∼ 938 nm thickness exhibited self-driven photoresponse with a responsivity of 4.3×10−8 A W−1 and detectivity of 3.5 × 106 jones respectively, under AM 1.5 G illumination conditions.

Infrared-light-driven SiN3 monolayer photocatalytic hydrolysis: A first-principles investigation

Although the immediate priority is to design low-price, non-poisonous hydrolytic photocatalysts, locating high-performance photocatalysts remains challenging. Herein, SiN3 monolayer with excellent stability was designed and comprehensively investigated by first-principles calculations. The results demonstrate that SiN3 monolayer displays ultra-high electron mobility of 7.41 × 104 cm2 V−1 s−1 and conspicuous anisotropy. Furthermore, the utilization of sunlight by SiN3 monolayer stretches to the infrared region with an optical absorption coefficient value ∼105 cm−1, which far exceeds classical photocatalyst MoS2. More particularly, the overpotential of SiN3 monolayer can operate as a driving force for spontaneous hydrogen evolution reaction without the external potential under solar radiation, which suggests that it is outstanding photocatalyst. Furthermore, strain engineering contributes to optical absorption of SiN3 monolayer, which is amplified by a 1.76-fold at 692 nm at just 4 % strain. The work not only reveals the prospective application of SiN3 monolayer in infrared-light-driven hydrolysis, but sheds some light on implementing large-scale solar hydrogen generation.

Effect of dip-coating cycle on some physical properties of Cu2NiSnS4 thin films for photovoltaic applications

Quaternary semiconductor Cu2NiSnS4 thin film was made by the sol–gel method associated with dip-coating technique on ordinary glass substrates. In this paper, we have studied the impact of dip-coating cycle at different cycles: 4, 5 and 6 on the structural, compositional, morphological, optical and electrical characteristics. CNTS thin films have been analyzed by various characterization techniques including X-ray diffractometer (XRD), Raman measurements, scanning electron microscope (SEM), energy-dispersive X-ray spectroscope (EDS), UV–Visible spectroscopy and four-point probe method. XRD spectra demonstrated the formation of cubic Cu2NiSnS4 with privileged orientation at (111) plane. Crystallite size of cubic CNTS thin films increases from 6 to 9 with augmentation of dip-coating cycle. Raman scattering confirmed the existence of CNTS thin films by Raman vibrational mode positioned at 332 cm−1. EDS investigations showed near-stoichiometry of CNTS sample deposited at five cycles. Scanning electron microscope showed uniform surface morphologies without any crack. UV–Vis spectroscopy indicated that the optical absorption coefficient values are larger than 104 cm−1. Estimated band gap energy of CNTS absorber layers decreases from 1.64 to 1.5 eV as dip-coating cycle increased. The electrical conductivity of CNTS thin films increases from 0.19 to 4.16 \(\left( {{\Omega }\;{\text{cm}}} \right)^{ - 1}\). These characteristics are suitable for solar cells applications.

Effect of substrate temperature on the growth of CuSbS2 thin films by chemical spray pyrolysis

CuSbS2 is an emerging potential compound semiconductor for absorber layer in thin film heterojunction solar cell. Spray pyrolysis technique has been successfully employed to deposit CuSbS2 thin films onto soda-lime glass substrates held at different substrate temperatures in the range of 220 °C–280 °C. The structural and optical analysis revealed that films deposited at 260 °C are CuSbS2 with chalcostibite structure. The films deposited at other substrate temperatures contained binary/ternary phases like Cu2-xS, Cu3SbS4 and Cu12Sb4S13. The lattice parameters of CuSbS2 films are found to be a = 0.599 nm, b = 0.379 nm and c = 1.449 nm respectively. The band gap of CuSbS2 films is close to the optimum band gap (1.5eV) required for highest theoretical photovoltaic conversion efficiency. The optical absorption coefficient value lies in the range of 104 cm−1. The nature of these films is found to be p-type.

Optical and conductivity studies of polyvinyl alcohol-MXene (PVA-MXene) nanocomposite thin films for electronic applications

A new family of 2D materials known as MXenes (Ti3C2Tx) is combined with polyvinyl alcohol (PVA) to form nanocomposites thin film with a thickness in micrometre range (7.20–7.88 µm) by using a relatively simple way, a drop-casting technique. The multi-layered structure of the MXenes bound together with PVA results in a high degree of structural disorder due to increasing defects in the nanocomposites. Detailed optical studies include UV–Vis absorption, optical absorption coefficient, extinction coefficient, and band gap energy determinations are conducted to investigate electromagnetic wave absorption capability of the nanocomposites. Resistivity measurement is studied as well. Electrical conductivity of the PVA is significantly increased with at least an improvement of 3000 times as compared to pure PVA (1 × 10−13 Sm−1). The highest σ value of 7.25 × 10−3 Sm−1 is found in the nanocomposites with a mass ratio of PVA to MXenes, 80:20 with its calculated optical absorption coefficient value in range 4000–5000 cm−1. The optical findings, as well as the electrical conductivity enhancement exhibited by these nanocomposites, explore the route to apply MXenes in polymer-based multifunctional nanocomposites for various applications such as optoelectronics, conductive filler, and electromagnetic absorbers.

Growth and Characterization of CZTS Thin Films Synthetized by Electrodeposition Method for Photovoltaic Applications

In the present work we deposited CZTS absorber material using a one-step electrodeposition method on ITO glass substrates. We studied the effect of sulfurization temperature on structural, morphological and optical properties of CZTS thin films sulfurized in N2+H2S atmosphere at 350, 375, 400 and 425°C for 10 min respectively for 10 min. The films have been charaterized by different techniques including X-ray diffractometer (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and UV-visible-NIR spectrophotometer. XRD patterns indicated kesterite CZTS with preferential orientation along (112) plane, the intensity of peaks increased with increase of sulfurization temperature signified the amelioration of the crystallinity with sulfurization temperature increased, the estimated crystallite size are in the range of 14.27-37.32 nm. Raman scattering experiments confirmed the presence of CZTS thin films by the characteristic peak at 336 cm−1. SEM images showed the morphology of CZTS thin films improved with increasing of sulfurization temperature. UV-Visible-NIR spectrophotometer showed that the values of optical absorption coefficient are larger than 104 cm−1 and optical band gap energy of CZTS thin films decreased with increasing of sulfurization temperature ranging 1.56 and 1.66 eV. These results make the electrodeposited CZTS films a suitable material as absorber material in solar cells applications based thin films.

DETERMINATION OF THE TEMPERATURE FIELD DURING LASER COAGULATION of CHORIORETINAL COMPLEX WITH OPTOACOUSTIC IN VITRO

The article describes a determination method of the laser radiation with specific parameters effect on the eye tissues based on optoacoustic probing. Low-power probing laser with 7-10 ns pulses generates acoustic waves at the aiming point. The waves propagate through the medium (saline in a cuvette) to acoustic receiver. The characteristics of the acoustic wave give basis for estimation of optical absorption coefficient - a parameter that determines temperature in the affected area after applying therapeutic laser. Calculation of the temperature pattern was performed using a three-dimensional thermal conductivity model that enabled determination of temperature distribution at any local point during coagulation and immediately after. To compare the results with pre-calculated temperature field values, direct temperature measurement was taken from the surface of the absorbing layer. The experiment was performed on six human chorioretinal tissue samples in vitro; the obtained optical absorption coefficient values did not exceed 120-300 cm -1 with maximum error margin of 20 %. The computational model was seen to be in good agreement with experimental thermocouple measurements.

Effects of anhydrous AlCl3 dopant on the structural, optical and electrical properties of PVA–PVP polymer composite films

Polymer composite films based on PVA–PVP with AlCl3 as the dopant at different concentrations were prepared using solution casting technique. XRD patterns reveal the increase in amorphousity of the films with AlCl3 doping. Optical absorption studies exhibit that the values of optical absorption coefficient, direct and indirect optical band gaps are found to decrease with increase in AlCl3 concentration. It confirms the charge transfer in complexes between the polymer and the dopant. The dielectric studies show the increase in dielectric constant at low frequency with increasing AlCl3 concentration and temperature. The ac conductivity and ionic conductivity increase with the AlCl3 content and the maximum value at room temperature is found to be 6.89 × 10−4 and 8.05 × 10−5 S/cm for higher AlCl3 doped PVA–PVP film. The estimated ionic conductivity value is three or four orders of magnitude greater than those obtained in the certain representative polymer-salt complexes as reported earlier. Electrical modulus plots confirm the removal of electrode polarization and the low conductivity relaxation time with Al doping. The activation energy estimated from the temperature dependent dc conductivity plot is agreed well with the migration energy calculated from the temperature dependent electric modulus plot.

Effect of Annealing Time on Cu2SnSe3 Thin Films Prepared by Successive Ionic Layer Adsorption and Reaction Method

Cu2SnSe3 thin films—an attractive candidate for a variety of optoelectronic and solar energy applications were prepared by successive ionic layer adsorption and reaction method and the effect of annealing time on structural, optical and electrical properties were studied. X-ray diffraction analysis revealed cubic sphalerite structure of Cu2SnSe3 thin films at 200 °C for both 1 and 2 h of annealing time. Average crystallite sizes of the Cu2SnSe3 films were found to be 39.56 and 31.65 nm for 1 and 2 h, respectively. Annealed films indicated high optical absorption co-efficient values (> 106 cm−1) in the wavelength range of 400–800 nm. However, the annealed film (1 h) showed slightly higher absorption co-efficient in comparison to 2 h and the band gap values were found to be 1.75 and 1.83 eV for 1 and 2 h annealed films, respectively. The resistivity of Cu2SnSe3 film annealed for 2 h increased (41.52 Ωm) in comparison to 1 h annealed film (25.65 Ωm). Due to the increased strain in 2 h annealed film, the dislocation density was higher and hence the optical and electrical properties of the film decreased.

Crystallized InBiS3 thin films with enhanced optoelectronic properties

In this paper, a one-step thermal evaporation approach was used for fabrication of indium bismuth sulphide thin films, and the synergetic effects of co-evaporation of two sources (indium granules and Bi2S3 powders) were investigated using different characterization techniques. X-ray diffraction (XRD) analysis confirmed the crystalline orthorhombic structure for the post-annealed samples. Surface roughness and crystal size of the obtained film samples were increased with increasing annealing temperatures. Analysis using X-ray photoelectron spectroscopy showed the formation of the InBiS3 structure for the obtained films, which is also confirmed by the XRD results. The optical absorption coefficient value of the annealed samples was found to be in the order of 105 cm−1 in the visible region of the solar spectrum. The optical band gap energy and electrical resistivity of the fabricated samples were observed to decrease (from 2.2 to 1.3 eV, and from 0.3 to 0.01 Ω–cm, respectively) with increasing annealing temperatures (from 200 to 350 °C), indicating the suitability of the prepared InBiS3 thin films for solar cell applications.

Magnetic field induced optical gain in a dilute nitride quaternary semiconductor quantum dot

Effects of magnetic field strength on the electronic and optical properties are brought out in a Ga0.661In0.339N0.0554As0.9446/GaAs quantum dot for the applications of desired wavelength in opto-electronic devices. The band alignment is obtained using band anticrossing model and the model solid theory. The magnetic field dependent electron-heavy hole transition energies with the dot radius in a GaInNAs/GaAs quantum dot are investigated. The magnetic field induced oscillator strength as a function of dot radius is studied. The resonant peak values of optical absorption coefficients and the changes of refractive index with the application of magnetic field strength in a GaInNAs/GaAs quantum dot are obtained. The magnetic field induced threshold current density and the maximum optical gain are found in a GaInNAs/GaAs quantum dot. The results show that the optimum wavelength for fibre optical communication networks can be obtained with the variation of applied magnetic field strength and the outcomes may be useful for the design of efficient lasers based on the group III-N-V semiconductors.

Studies on the growth, spectral, structural, electrical, optical and mechanical properties of Uronium 3-carboxy-4-hydroxybenzenesulfonate single crystal for third-order nonlinear optical applications

Organic Uronium 3-carboxy-4-hydroxybenzenesulfonate (UCHBS) nonlinear optical single crystal was grown by solution growth technique. The solubility and nucleation studies were performed for UCHBS at different temperatures 30, 35, 40, 45, 50 and 55°C. The crystal structure of UCHBS was elucidated from single crystal X-ray diffraction study. High resolution X-ray diffraction technique was employed to study the perfection and internal defects of UCHBS crystal. Infrared and Raman spectra were recorded to analyze the vibrational behavior of chemical bonds and its functional groups. The physico-chemical changes, stability and decomposition stages of the UCHBS compound were established by TG–DTA studies. The dielectric phenomenon of UCHBS crystal was studied at different temperatures with respect to frequency. Linear optical properties of transmittance, cut-off wavelength, band gap of UCHBS were found from UV–visible spectral studies. Third-order nonlinear optical susceptibility, nonlinear refractive index, nonlinear optical absorption coefficient values were measured by Z-scan technique. The mechanical properties of UCHBS crystal was studied by using Vicker’s microhardness test. The growth features of UCHBS crystal were analyzed from etching studies.

Cu2SnS3 absorber thin films prepared via successive ionic layer adsorption and reaction method

Abstract In this paper, we report the production of Cu2SnS3 thin films with high phase purity via successive ionic layer adsorption and reaction method on soda lime glass substrates. Structural, morphological, compositional, optical and electrical investigations were carried out. The X-ray diffraction patterns of the samples matched very well with the reference pattern and proved the polycrystalline nature of the films. As a secondary phase, one weak peak indicating covallite Cu2–xS phase was observed in the pattern of the sample deposited by using equimolar Cu and Sn. The surface morphologies of the films were found to be continuous and composed of homogeneously distributed large grains. From the reflectance and transmittance data, the optical absorption coefficient values of the films were found to be about 104 cm−1 and the films were found to be almost opaque in the wavelengths from 200 to 600 nm with a small reflectivity of about 10%. Band gap values of the films decreased from 1.45 to 1.35 eV with decreasing Cu content. Electrical characterization showed that the films were p-type semiconductor. Two different impurity levels for each film were found via resistivity-temperature characteristics.

Enabling in vivo measurements of nanoparticle concentrations with three‐dimensional optoacoustic tomography

In this report, we demonstrate the feasibility of using optoacoustic tomography (OAT) to evaluate biodistributions of nanoparticles in animal models. The redistribution of single-walled carbon nanotubes (SWCNTs) was visualized in living mice. Nanoparticle concentrations in harvested organs were measured spectroscopically using the intrinsic optical absorption and fluorescence of SWCNTs. Observed increases in optoacoustic signal brightness in tissues were compared with increases in optical absorption coefficients caused by SWCNT accumulation. The methodology presented in this report can further be extended to calibrate the sensitivity of an optoacoustic imaging system for a range of changes in optical absorption coefficient values at specific locations or organs in a mouse body to enable noninvasive measurements of nanoparticle concentrations in vivo. Additionally, qualitative information provided by OAT and quantitative information obtained ex vivo may provide valuable feedback for advancing methods of quantitative analysis with OAT.

Dielectric confinement on exciton binding energy and nonlinear optical properties in a strained Zn1−xinMgxinSe/Zn1−xoutMgxoutSe quantum well

The band offsets for a Zn1−xinMgxinSe/Zn1−xoutMgxoutSe quantum well heterostructure are determined using the model solid theory. The heavy hole exciton binding energies are investigated with various Mg alloy contents. The effect of mismatch between the dielectric constants between the well and the barrier is taken into account. The dependence of the excitonic transition energies on the geometrical confinement and the Mg alloy is discussed. Non-linear optical properties are determined using the compact density matrix approach. The linear, third order non-linear optical absorption coefficient values and the refractive index changes of the exciton are calculated for different concentrations of magnesium. The results show that the occurred blue shifts of the resonant peak due to the Mg incorporation give the information about the variation of two energy levels in the quantum well width.

A simple quality factor for characterization of thin silicon films

Four series of intrinsic thin Si films were prepared by plasma enhanced chemical vapor deposition at standard and high growth rate conditions. We suggest a simple ‘μc-Si:H layer quality factor’ based on the ratio of subgap optical absorption coefficient values: α(1.4eV)/α(1eV). This ratio minimizes the light scattering effects for rough films and can serve as a reliable detection of the amorphous/microcrystalline structure transition and also as a figure of merit for the microcrystalline layer. The quality factor is evaluated for series of our samples with well known structure and also compared with samples from other laboratories with different deposition and measurement techniques.

About the effective thermal and optical parameters of a two-layer structure in photothermal phenomena

The model for the ca1culation of effeetive thermal parameters in two-layer structure in photoacoustic phenomena proposed in previous works (1-4) is used for defining and ca1culating the effective optical parameters. The concept of effective optical absorption coefficient will naturally emerge from the model when a heat source, depending on the position and the optical absorption coefficient, is taken into account. Results for the static limit shows that, in general case, the effective optical absorption coefficient value depends on the effeetive thermal conductivity, and it is different for rear-surface and front-surface illumination configurations. For optically opaque samples in rear-illumination configuration and optically transparent layers, it is show that the effective optical absorption coefficient and the effective thermal conductivity are independent and can be separately obtained. The latter result suggests for optically transparent samples, it will be correet to use the Maxwell Equations for defining and ca1culating the effeclive oplical parameters in multilayer structures.

Thickness of diamond-like carbon coatings quantified with Raman spectroscopy

A model is developed for quantifying the thickness of thin coatings and wear scars using Raman spectroscopy. The model, which assumes that both incident and Raman light obey Beer's law, was applied to Raman spectra from a diamond-like carbon (DLC) coating containing Si and O, known as DLN (diamond-like nanocomposite). The coatings ranged in thickness from 10 nm to 2 μm, according to stylus profilometry. Systematic variations in the Raman carbon (G band) and Si (1st order) peak intensities vs. thickness were found. Fits to the model gave an optical mean free path of λ∼250 nm for DLN. This value is in good agreement with optical absorption coefficient values of other DLC films. Thickness profiles of wear tracks in the coatings determined by the model compared well with depths determined by profilometry.