UV Vis NIR Absorption Research Articles

Synthesis, crystal growth, crystal investigation, optical, thermal, DFT and NLO studies of 2-methylanilinium- 4-methylbenzenesulfonate organic single crystal: Experimental and computational approach

1:1 Molecular adducts of 2-methylanilinium-4-methylbenzene-1-sulfonate (2MA4MBS) were synthesized and grown as a single crystal by slow evaporation elucidation procedure using aqueous medium, where 2-methylaniline acts as an acceptor and 4-methylbenzene-1-sulfonic acid acts as donor. X-ray diffraction analysis reveals that 2MA4MBS, a member of monoclinic crystal arrangement with space group P21/n. The determined unit cell dimensions are a = 12.7112(12) Å, b = 6.9448(5) Å, c = 16.1278(15) Å, β = 106.734(6)° and volume = 1363.4(2)Å3. TGA and DTA were used to evaluate the thermal properties of 2MA4MBS, which revealed excellent thermal efficiency of the produced crystals up to 180 °C. UV–Vis-NIR absorption spectra was employed to describe the crystal's absorbance in the stretch of 200–800 nm, and absorbance band maximum was determined to be at 225 nm. DFT studies has been performed on the titular compound in order to obtain stable structure, vibrational wavenumbers, there is an inter and intramolecular charge shift within the compound. Single crystal's comparative SHG reliability was determined to be 1.7 times superior to the KDP standard. With conventional KDP, the laser damage threshold for the generated crystal is 0.86 GW/cm2.

Structure and optical properties of GeTe film controlled by amorphous to crystalline phase transition

GeTe films have been showed great applications in the field of optical devices, especially in infrared absorption due to their narrow band gap. In this paper, amorphous GeTe (a-GeTe) film was prepared by pulsed laser deposition. Then, crystalline GeTe (c-GeTe) film was obtained by annealed in a tubular furnace at 200 °C. The X-ray diffraction indicates that GeTe film is transferred from amorphous to crystalline phase after annealing. The X-ray photoelectron spectroscopy shows that the presence of Ge and Te elements corresponding to the structure of GeTe. The high resolution transmission electron microscope also indicates that the disordered structure of GeTe film is transferred into ordered. Compared with a-GeTe film, the optical property of c-GeTe film has higher absorbance at 0.94 on 1100 nm measured by UV–Vis–NIR absorption spectroscopy. According to the calculation results, the optical band gaps of c-GeTe film and a-GeTe film are 0.82 eV and 0.87 eV respectively, indicating that the c-GeTe films is more favorable for photon transition. Fourier transform infrared spectroscopy also confirms that the infrared absorption properties of c-GeTe films is superior to those of the a-GeTe film. These results provide a fundamental research for the application of c-GeTe film in the field of infrared absorption.

Spectral characteristics of Tb3+ doped ZnF2–K2O–Al2O3–B2O3 glasses for epoxy free tricolor w-LEDs and visible green laser applications

In the current work, a series of Zinc Potassium Alumino fluoroborate (ZKAlFB) glasses doped with different concentrations of Terbium ions (Tb3+) were synthesized by employing the melt-quench technique. The spectroscopic properties of the as-prepared glass samples were examined using characterization techniques like XRD, FT-IR, DSC, UV–vis–NIR absorption and emission to unlock their utility in photonic devices. Absorption spectral information was used to determine the nature of bonding between Tb3+ ions and its surrounding ligands. FT-IR spectral information recorded for an undoped glass has been used to understand various functional groups present in the as-prepared ZKAlFB glass. The DSC thermogram was used to estimate glass thermal stability (ΔT) and transition temperature (Tg) of the as-prepared ZKAlFB glass. The Judd-Ofelt (J-O) intensity parameters estimated from absorption spectral data are correlated with the emission spectral profiles to estimate radiative properties. The photoluminescence (PL) intensity of the as-prepared ZKAlFBTb glasses is found to be maximum for 1 mol% of Tb3+ ions and beyond decreases showing concentration quenching. Using PL spectral data, the CIE color coordinates, and Correlated Color Temperature (CCT) values were evaluated to understand the suitability of the as-prepared glasses for green color emitting photonic devices. The experimental lifetime values estimated from the decay profiles are decreasing with elevation in Tb3+ ion concentration due to energy transfer through the cross-relaxation process. Quantum efficiency (η), emission cross-section (σse), CIE and CCT values obtained for 1 mol% Tb3+ ions doped ZKAlFB glass demonstrates its superiority in fabricating epoxy free tricolor w-LEDs and visible green lasers.

Structural, optical, morphological properties of silver doped cobalt oxide nanoparticles by microwave irradiation method

The synthesis of silver doped cobalt oxide nanoparticles by microwave-assisted method and their structural, optical, antibacterial activities are presented in this study. The doping concentrations were chosen as 5, 10, 15, and 20 wt percentages. The sample was undergone powder X-ray diffraction studies and the result shows the good crystalline nature of the sample. Also, the average crystallite size increases from 13.95 nm, 21.26 nm, 26.13 nm, and 28.35 nm with different doping concentrations. The transmission electron microscopy image shows cubic and spherical morphology. The optical properties were tested by UV–vis–NIR absorption spectrum. It indicates the decrease of band gap value. From the antibacterial activity studies, the 20 wt % Ag doped nanoparticles exhibit better activity.

Optical and Thermal Properties of Acid Red Doped Triglycine Acetate Crystal for Optoelectronic Applications

AbstractA positive change in crystal can be induced by dye. Pure and Acid Red 1 dye (AR) doped triglycine acetate (TGAc) single crystals are synthesized by solution approach to enrich the characteristics of pure TGAc crystals. The crystalline nature of the grown crystals is investigated using powder X‐ray diffraction. The Scherrer method has been used to calculate the crystallite size of both developed crystals and is compared to the Williamson and Hall method. Fourier transform infrared spectroscopy confirms the existence of several functional groups as well as dye inclusion in the produced crystals. Four distinct absorption bands are found in UV–vis–NIR absorption spectra at the location where AR dye is inserted into the TGAc matrix. Different optical constants, such as optical bandgap (Eg), extinction coefficient (k), refractive index (n) and optical conductivity (σ) are measured for both samples based on transmittance measurements. The thermal stability and decomposition temperature of 0.05 mol% AR dye doped TGAc are found to be higher. The doped crystals' improved optical characteristics and thermal stability prove their applicability for optoelectronic applications.

Effect of Co‐Solvents on the Crystallization and Phase Distribution of Mixed‐Dimensional Perovskites

AbstractSolution‐processed quasi‐2D perovskites are promising for stable and efficient solar cells because of their superior environmental stability compared to 3D perovskites and tunable optoelectronic properties. Changing the number of inorganic layers (n) sandwiched between the organic spacers allows for tuning of the bandgap. However, narrowing the phase distribution around a specific n‐value is a challenge. In‐situ UV–vis–NIR absorption spectroscopy is used to time‐resolve the crystallization dynamics of quasi‐2D butylammonium‐based (BA) perovskites with <n> = 4, processed from N,N‐dimethylformamide (DMF) in the presence of different co‐solvents. By combining with photoluminescence, transient absorption, and grazing‐incidence wide‐angle X‐ray scattering, the crystallization is correlated to the distribution of phases with different n‐values. Infrared spectroscopy and density functional theory reveal that the phase distribution correlates with perovskite precursor—co‐solvent interaction energies and that stronger interactions shift the phase distribution towards smaller n‐values. Careful tuning of the solvent/co‐solvent ratio provides a more homogeneous phase distribution, with highly oriented perovskite crystals and suppressed formation of n = 1–2 phases, providing a power conversion efficiency for BA2MA3Pb4I13 solar cells that increases from 3.5% when processed from DMF to over 11% and 10% when processed from DMF/dimethyl sulfoxide and DMF/N‐methyl‐2‐pyrrolidone mixtures, respectively.

Synthesis, structure, and optical properties of nanopowders CdS: xAl (x=0, 1, 5, 10, 15 and 20%) via the sol–gel technique

The nanocrystalline Al-doped CdS semiconductors were produced accurately by the sol-gel calcination process. The aluminum was added with different percent’s (0, 1, 5, 10, 15, and 20 wt%) to the synthesized CdS. Both FT-Raman analysis and UV–VIS-NIR absorption measurements were utilized to characterize the studied semiconductors' structural and optical characteristics. The detected X-ray diffraction (XRD) patterns of the prepared CdS present a polycrystalline structure, and Al-doping does not significantly impact this range. Optical bandgaps were determined for undoped and Al-doped CdS, showing a significant change with the percentage of Al-dopants. With increasing Al-doping up to (20 percent), the optical bandgap for CdS (2.38 eV) grows to reach (2.47 eV) and the allowed transitions were found to be direct for the investigated samples. The blue shift may be the reason for the optical bandgap variations. Scanning Electron Microscope (SEM) micrographs were performed to establish the Al-doped CdS nanostructure to identify the morphological characteristics.

Design, photoelectric properties and electron transition mechanism of Cr doped p-CuGaS2 compound based on intermediate band effect

The p-CuGaS2 and Cr doped p-CuGaS2 compounds are first fabricated by the solvothermal method using CuI, C12H26S, C15H21GaO6, and C15H21CrO6 as starting materials. The Cr3+ is successfully doped into the CuGaS2 compounds with a single chalcopyrite structure and partially replaced Ga3+. The two additional sub-bandgap optical absorption edges (‘B’ and ‘C’) are observed in the UV–Vis–NIR absorption spectra of the sample with a Cr doping content of 0.99%. ‘C’ and ‘B’ correspond to the absorption extra photons of hν1 (valence band maxima intermediate band, 0.8 eV) and hν2 (intermediate band conduction band minimum, 1.2 eV), which proves the formation of the intermediate band in the Cr doped CuGaS2. The Hall effect measurement shows that the resistivity of Cr doped CuGaS2 compound decreases with the increase of Cr doping content, while the carrier concentration and mobility are increased. The half-filled state of intermediate band is confirmed according to Fermi level tested by the ultraviolet photoelectron spectroscopy. The photocurrent responses analysis suggests that the intermediate band leads to the increase of photo-induced carriers. The band structure and electron transition mechanism of Cr doped CuGaS2 compounds are discussed in details.

From metallic to semiconductor conversion of single-walled carbon nanotubes by chlorination

In this research, single-walled carbon nanotubes (SWCNTs) were treated with strong HClO4 acid. Then investigated first by UV–vis-NIR absorption, Fourier transform infrared (FTIR) and Raman spectroscopy; and secondly by numerical calculations based DFT using generalized GGA and LDA as implemented in SIESTA code. The results show significant changes in the behavior of metallic nanotubes and DFT calculations (GGA and LDA) show that adsorption of chlorine atoms on the metallic (9,9) carbon nanotubes wall generates an energy gap in the electronic structure of these nanotubes, confirming the experimental results. This highlights a conversion of metallic nanotube to semiconductor.

Imide-Based Multielectron Anolytes as High-Performance Materials in Nonaqueous Redox Flow Batteries

Recent developments toward high-energy-density all-organic redox flow batteries suggest the advantageous use of molecules exhibiting multielectron redox events. Following this approach, organic anolytes are developed that feature multiple consecutive one-electron reductions. These anolytes are based on N-methylphthalimide, which exhibits a single reversible reduction at a low potential with good cycling stability. Derivatives with two or three imide groups were synthesized to enable multielectron reduction events. By incorporating suitably designed side chains, a volumetric capacity of 65 Ah/L is achieved in electrolyte solutions. Bulk-electrolysis experiments and UV–vis–NIR absorption spectroscopy revealed good cycling stability for the first and second reduction of monoamides and diimides, respectively, but a loss of stability for the third reduction of triimides. We identify N-2-pentyl-N′-2-(2-(2-methoxyethoxy)ethoxy)ethylaminepyromellitic diimide as a very promising multielectron anolyte with an excellent volumetric capacity and superior cycling and shelf-life stability compared to monoimides and triimides. The outstanding performance of this anolyte was demonstrated in proof-of-principle redox flow batteries that reach an energy density of 24.1 Wh/L.

Synthesis and properties of 3,4‐dioxythiophene and 1,4‐dialkoxybenzene based copolymers via direct CH arylation: Dopant‐free hole transport material for perovskite solar cells

AbstractDirect CH arylation coupling reaction has gained significant importance in synthesis of conjugated polymers for organic electronic applications. We report here a facile and straightforward method called “direct CH arylation” reaction to synthesize conjugated 3,4‐dioxythiophene and 1,4‐dialkoxybenzene based copolymers as hole transport material (HTM) for perovskite solar cells. Two electron‐rich conjugated polymers P1‐2 were synthesized, in which 1,4‐dibromo‐2,5‐bis(dodecyloxy)benzene and 3,4‐dialkoxy‐thiophene units were used for polymerization. The resulting polymers were characterized and exhibited high solubility in organic solvents. Electrochemical and optical characterizations were carried out by cyclic voltammetry and UV–Vis–NIR absorption spectroscopy and found that these polymers show higher‐lying HOMO energy levels with wide band gap. Density functional theory calculation was performed on these polymers (P1‐2) and correlated with our experimental results. Finally, perovskite solar cells were fabricated by solution‐processable deposition of P1‐2 as dopant‐free HTM with device geometry ITO/SnO2/Perovskite/HTM(P1/P2)/Ag and achieved a maximum power conversion efficiency of 5.28%. This study provides information on designing and simple preparation by direct CH arylation reaction of higher‐lying HOMO energy level polymer as HTM for perovskite solar cells.

Anionic-Surfactant-Stabilized Hydrophobic Ionic-Liquid-Based Bicontinuous Microemulsion as a Medium for Enzymatic Oxidative Polymerization of Aniline.

The hydrophobic ionic liquid [C8mim][PF6] (1-octyl-3-methylimidazolium hexafluorophosphate)-based bicontinuous microemulsion stabilized by the anionic surfactant [C4mim][AOT] (1-butyl-3-methylimidazolium bis(2-ethylhexyl) sulfosuccinate) was first tried as a medium for horseradish peroxidase (HRP)-triggered oxidative polymerization of aniline. The effects of the mass ratio of [C8mim][PF6]-to-water (α), the mass fraction of [C4mim][AOT] in the total mixture (γ), and temperature (T) on the enzymatic polymerization were investigated using UV–vis–NIR absorption, electron spin resonance, and small-angle X-ray scattering spectroscopy techniques. The bicontinuous microemulsion is demonstrated to play a template role in the biosynthesis of polyaniline (PANI). The conductivity of the resulting PANI depends on the microemulsion microstructure and the microstructure- and T-dependent catalytic properties of the solubilized HRP. With the increase in α, the conductivity of the synthesized PANI decreases due to the increase in the template curvature (decrease of the microdomain size) and the decrease in the activity and stability of HRP. Compared with α, γ has little effect on the microdomain size of the template; so, the γ-dependent change in the conductivity of PANI is mainly caused by the changes of the microstructure-dependent activity and stability of HRP. Over the range of 20–35 °C, T has little effect on the microdomain size, but it greatly changes the activity and stability of HRP. With the increase in T, the activity of HRP increases steadily, but its stability decreases significantly, which should be one of the reasons why the conductivity of PANI decreases with increasing T. In conclusion, lower values of α, γ, and T are favorable for the biosynthesis of conductive PANI. The present study not only deepens the insight into the role of the template in the process of PANI synthesis, but also opens up a green new way for the biosynthesis of the conducting polymer.

Identification of Pink-Coloured CVD Synthetic Diamonds from Huzhou Sino-C Semiconductor Co. in China

In recent years, increasing numbers of pink-coloured CVD synthetic diamonds have appeared on the market. One of the major sources is Huzhou SinoC Semiconductor Science and Technology Co., Ltd., Zhejiang province of China. In this article, seven pink-coloured CVD-grown diamonds produced in the last two years by Huzhou have been investigated and identified, including their gemological and spectroscopic characteristics. In DiamondView, they fluoresced orange–red, with an obscure striated growth structure, which is common for CVD synthetics. The mid-IR absorption spectra of these samples showed some single nitrogen and hydrogen-related features (1130, 1344, 3123, 3323 cm−1), which indicated that the diamonds were type Ib and were CVD-grown diamonds. The H1a defect annealed out at approximately 1400 °C, whereas the 3107 cm−1 defect was produced by annealing above 1700 or 1800 °C. This implied that the samples had undergone two separate heat treatments: first, a high-temperature anneal (possibly an HPHT treatment to reduce any brown colour), which would have produced the 3107 cm−1 defects and a small number of A centres, followed by irradiation, followed by annealing above 800 °C to make the vacancies mobile. The UV–Vis–NIR absorption spectra showed distinct NV-related features (575 and 637 nm), the main reason for the pink colour. Photoluminescence spectra obtained at liquid nitrogen temperature recorded radiation-related emissions (388.9, 503.5 nm), a strong N-V centre, H3 and H2 defects, and many unassigned emissions. These pink CVD products can be separated from natural and treated pink-coloured diamonds by a combination of optical spectroscopic properties, such as fluorescence colour, and absorption features in the infrared and UV–Vis regions.

Low field magnetic interactions in the transition metals doped CuS quantum dots

Polyvinlypyrrolidone (PVP) capped and magnetic transition metals (TM = Fe, Co and Cr) doped CuS quantum dots (Cu1-xTMxS; x = 0.02 & 0.04) were synthesized by low entropy facile chemical co-precipitation method. The structural, optical and magnetic characterizations of the synthesized QDs were done by using X-ray diffraction (XRD) technique, UV–Vis-NIR absorption spectroscopy, photoluminescence (PL) spectroscopy and superconducting quantum interference device (SQUID) respectively. The low field non-linearity and the presence of coercivity in the M−H loops indicate the presence low field magnetic (spin–spin) interactions between the doped cations.

Effects of Vanadium on the Structural and Optical Properties of Borate Glasses Containing Er3+ and Silver Nanoparticles.

The erbium-vanadium co-doped borate glasses, embedded with silver nanoparticles (Ag NPs), were prepared to improve their optical properties for potential optical fiber and glass laser application. The borate glasses with composition (59.5–x) B2O3–20Na2O–20CaO–xV2O5–Er2O3–0.5AgCl (x = 0–2.5 mol%) were successfully prepared by conventional melt-quenching method. The structural properties of glass samples were investigated by XRD, TEM and by Fourier transform infrared (FTIR) spectroscopy while optical properties were carried out by UV–Vis spectroscopy by measuring optical absorption and the emission properties were investigated by photoluminescence spectroscopy. The XRD patterns confirmed the amorphous nature of the prepared glass samples whilst the FTIR confirmed the presence of VO4, VO5, BO3 and BO4 vibrations. UV–Vis–NIR absorption spectra reveal eight bands which were located at 450, 490, 519, 540, 660, 780, 980, and 1550 nm corresponding to transition of 4F5/2, 4F7/2, 2H11/2, 4S3/2, 4F9/2, 4I9/2, 4I11/2, and 4I13/2, respectively. The optical band gap (Eopt), Urbach energy and refractive index were observed to decrease, increase and increase, respectively, to the addition of vanadium. Under 800 nm excitation, three emission bands were observed at 516, 580 and 673 nm, which are represented by 2H11/2–4I15/2, 4S3/2–4I15/2 and 4F15/2–4I15/2, respectively. The excellent features of achieved results suggest that our findings may provide useful information toward the development of functional glasses.

Water Intake and Ion Exchange in PEDOT:Tos Films upon Cyclic Voltammetry: Experimental and Molecular Dynamics Investigation

Conductive polymer PEDOT:Tos (3,4-ethylenedioxythiophene doped with molecular tosylate) gained considerable attention in various devices for bioelectronic applications, such as organic transistors and sensors. Many of these devices function upon oxidation/reduction processes in contact with aqueous electrolytes. So far, theoretical insight into morphological changes, ion injection, and water intake during these processes was rather limited. In the present work, we combined experiments and molecular dynamics simulations to study the water intake, swelling, and exchange of ions in the PEDOT:Tos film during cyclic voltammetry. We showed that the film underwent significant changes in morphology and mass during the redox processes. We observed both experimentally and in simulations that the film lost its mass during reduction, as tosylate and Na were expelled and gained mass during oxidation mainly due to the uptake of anions, i.e., tosylate and Cl. The results were in line with the UV–VIS–NIR absorption measurements and X-ray photoelectron spectroscopy (XPS) measurements, which revealed that during the redox process a portion of Tos was replaced by Cl– as the counterion for PEDOT. Also, the relative mass change between the most oxidized and reduced states was ∼10 to 14% according to both experiments and simulations. We detected an overall material loss of the film during voltammetry cycles indicating that a portion of the material leaving the film during reduction did not return to the film during the consecutive oxidation. Our combined experimental/simulation study unraveled the underlying molecular processes in the PEDOT:Tos film upon the redox process, providing the essential understanding needed to improve and assess the performance of bioelectronic devices.

Preparation and characterization of CuGaS2 chalcopyrite nanoparticles via a facile solvothermal method

CuGaS2 (CGS2) chalcopyrite semiconductor has the potential to be widely used in many fields. In order to further optimize the solvent thermal preparation technology and explore the reaction mechanism of CGS2, by adjusting the reaction temperature and annealing temperature, we have designed a facile and short period preparation scheme of solvothermal reaction for 30 min followed by annealling for 30 min. Finally, CGS2 nanoparticles with chalcopyrite structure were obtained. XRD, FESEM, EDAX, XPS, Raman spectra, and UV–Vis-NIR absorption spectra have been characterized. Although further research is needed, we believe that this method has potential applications in the preparation of other ternary or quaternary chalcogenides.

The novel approach of stability aspect in organic oligoene dye for dye-sensitized solar cell applications

The phenyl-conjugated oligoene dye 2-cyano3-(4-diphenylaminophenyl)prop-2-enoic acid (SKS) was synthesized by chemical method, and its structure was confirmed by 1H NMR and 13C NMR analysis. Solar cell was made using TiO2 (P-25) as photoanode, synthesized oligoene SKS dye as sensitizer, I-/I3- as electrolyte, and platinum as counter electrode. The overall power conversion efficiency of SKS dye based solar cell was 1.76 %. The functional groups were identified from the FTIR spectrum. The optical, electrochemical, and thermal properties were analyzed. The photostability of SKS dye was analyzed before and after various light irradiation by UV-Vis NIR absorption spectrum.

L-Histidinium iodide semi-organic crystal for optical frequency conversion applications

Single crystal of semi-organic L-Histidinium iodide (LHI) was grown by slow evaporation technique. Single crystal X-ray diffraction study confirms that the LHI crystallizes in monoclinic crystal system with space group P21. The functional groups in a LHI molecule were characterized by infrared and Raman spectra. The UV–Vis–NIR absorption spectrum of the grown LHI crystal was recorded and the band gap energy of the crystal was calculated and it is 3.75 eV. Fluorescence spectroscopy throws light on the optical emission properties.TG-DSC analysis indicate that the LHI crystal was stable up to 254.8 °C. The second harmonic generation behavior of the grown LHI crystal was tested by Kurtz-Perry powder technique.

Effect of gamma irradiation on physical, optical, spectroscopic and structural properties of Er3+-doped vitreous zinc borotellurite

In the present report, erbium doped zinc borotellurite glasses were irradiated with 50 kGy gamma radiation using a60Co radioisotope source. The effect of gamma irradiation on the physical, structural, optical and spectroscopic properties of erbium doped zinc borotellurite glasses was studied. Also the shielding properties of the un-irradiated glasses were studied with the help of Phy-X/PSD software. The gamma irradiation caused some structural changes as indicated by FTIR and Raman studies which may be due to the formation of the new structural units. Its influence on the optical properties like band gap (direct and indirect band gap), Urbach energy and refractive index were analyzed with the help of UV–Vis–NIR spectrometer. The UV–Vis–NIR absorption spectra showed increase in absorption after the gamma irradiation. The optical band gap value decreased for the irradiated samples. The spectroscopic properties such as stimulated emission cross-section, bandwidth, lifetime etc. Got marginally modified due to gamma irradiation. The shielding properties of the un-irradiated glasses were improved with the increasing rare earth concentration. The glasses with rare earth doping showed less changes in their properties after gamma irradiation which indicates that these glasses are more resistant to gamma radiation as compared to the base glass.