Ultraviolet-visible-near Infrared Research Articles

Investigation of pure and Sn-doped Ca(OH)2 nanoparticles for optical and biomedical applications

The present study explores the synthesis and characterization of pure and Sn-doped Ca(OH)2 nanoparticles, highlighting their potential for optical and biomedical applications. The incorporation of Sn into the Ca(OH)2 matrix is investigated for the first time, providing insights into its impact on the structural, optical, and biological properties of the nanoparticles. A straightforward precipitation method was employed to synthesize pure and Sn-doped calcium hydroxide nanoparticles. The synthesized nanoparticles were characterized by using X-ray diffraction (XRD) pattern, ultraviolet–visible–near infrared (UV-Vis-NIR) spectra, Fourier Scanning Electron Microscope (FESEM) micrographs, and agar well diffusion method for antibacterial study. X-ray diffraction examinations confirmed the polycrystalline nature of the Ca(OH)2 nanoparticles and revealed the structure to be hexagonal. The average crystallite size of the pure and Sn-doped Ca(OH)2 nanoparticles are 49 nm and 66 nm, respectively. The FESEM images of the sample revealed the formation of pure Ca(OH)2 nanoparticles in the form of nanoflakes and the change in the morphology while doping Sn with Ca(OH)2. The prepared samples were assessed using UV-Vis-NIR spectra, showing the UV absorption band at approximately 247 and 263 nm for the samples of pure and Sn-doped Ca(OH)2 nanoparticles, respectively. The calculated direct and indirect allowed band gap energies were found to be 4.04 and 3.92 eV for pure Ca(OH)2, and 3.37 and 2.94 eV in the case of Sn-doped Ca(OH)2. The antibacterial effectiveness of Ca(OH)2 nanoparticles was assessed using the well diffusion method, and it was observed that both the samples of pure and Sn doped Ca(OH)2 nanoparticles exhibited significant antibacterial properties against gram-negative bacterial strains. An elevation in Minimum Inhibitory Concentration (MIC) values for Sn-doped Ca(OH)2 nanoparticles compared to pure Ca(OH)2 nanoparticles was observed when examining their impact on Gram-negative bacteria (Klebsiella pneumoniae), which suggested a requirement for a higher concentration due to the nature of surface charges present in order to inhibit the growth of microorganisms.

Characterization of Heavy Minerals and Their Possible Sources in Quaternary Alluvial and Beach Sediments by an Integration of Microanalytical Data and Spectroscopy (FTIR, Raman and UV-Vis)

Quaternary stream sediments and beach black sand in north-western Saudi Arabia (namely Wadi Thalbah, Wadi Haramil and Wadi Al Miyah) are characterized by the enrichment of heavy minerals. Concentrates of the heavy minerals in two size fractions (63–125 μm and 125–250 μm) are considered as potential sources of “strategic” accessory minerals. A combination of mineralogical, geochemical and spectroscopic data of opaque and non-opaque minerals is utilized as clues for provenance. ThO2 (up to 17.46 wt%) is correlated with UO2 (up to 7.18 wt%), indicating a possible uranothorite solid solution in zircon. Hafnoan zircon (3.6–5.75 wt% HfO2) is a provenance indicator that indicates a granitic source, mostly highly fractionated granite. In addition, monazite characterizes the same felsic provenance with rare-earth element oxides (La, Ce, Nd and Sm amounting) up to 67.88 wt%. These contents of radionuclides and rare-earth elements assigned the investigated zircon and monazite as “strategic” minerals. In the bulk black sand, V2O5 (up to 0.36 wt%) and ZrO2 (0.57 wt%) are correlated with percentages of magnetite and zircon. Skeletal or star-shaped Ti-magnetite is derived from the basaltic flows. Mn-bearing ilmenite, with up to 5.5 wt% MnO, is derived from the metasediments. The Fourier-transform infrared transmittance (FTIR) spectra indicate lattice vibrational modes of non-opaque silicate heavy minerals, e.g., amphiboles. In addition, the FTIR spectra show O-H vibrational stretching that is related to magnetite and Fe-oxyhydroxides, particularly in the magnetic fraction. Raman data indicate a Verwey transition in the spectrum of magnetite, which is partially replaced by possible ferrite/wüstite during the measurements. The Raman shifts at 223 cm−1 and 460 cm−1 indicate O-Ti-O symmetric stretching vibration and asymmetric stretching vibration of Fe-O bonding in the FeO6 octahedra, respectively. The ultraviolet-visible-near infrared (UV-Vis-NIR) spectra confirm the dominance of ferric iron (Fe3+) as well as some Si4+ transitions of magnetite (226 and 280 nm) in the opaque-rich fractions. Non-opaque heavy silicates such as hornblende and ferrohornblende are responsible for the 192 nm intensity band.

Functionalized cements incorporated with nanocomposite photocatalysts for self-cleaning applications

The constantly escalating pollution on the surface of cement-based materials affects architectural aesthetics and residents′ health, necessitating frequent cleaning and maintenance, which contradicts the concept of sustainable development. This study aimed to develop a novel photocatalytic cement material to enhance the self-cleaning capabilities of cement-based materials, thereby extending their service life and reducing maintenance costs. To achieve this, carbon quantum dots (CDs) and g-C3N4 (CN) nanocomposite photocatalysts (CDs@CN) were synthesized and integrated into white cement to prepare photocatalytic cements. The materials were characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and ultraviolet–visible–near infrared (UV–Vis–NIR) spectroscopy. Photocatalytic performance was evaluated by the degradation of Rhodamine B (RhB) under xenon (Xe) lamp, Vis light and UV light. The CDs@CN nanocomposite displayed superior photocatalytic activity, particularly under Xe lamp irradiation, achieving over 95 % degradation of RhB within 1 h. Even under Vis and UV light, the photocatalytic cement retains robust self-cleaning capabilities, achieving pollutant degradation rates of 81 % and 63 %, respectively, within 1 h. This performance exceeded that of pristine CN and control samples, demonstrating effective light absorption and charge separation. The optimal photocatalyst concentration in cement was identified as 0.1∼5.0 wt%, balancing performance and dispersion. The developed CDs@CN-based photocatalytic cement material offers a sustainable solution for self-cleaning and environmental purification. This study provides insights into the design of functional cementitious materials and contributes to the sustainable development of the construction industry.

A bis-Phenolate Carbene-Supported bis-μ-Oxo Iron(IV/IV) Complex with a [FeIV(μ-O)2FeIV] Diamond Core Derived from Dioxygen Activation.

The diiron(II) complex, [(OCO)Fe(MeCN)]2 (1, MeCN = acetonitrile), supported by the bis-phenolate carbene pincer ligand, 1,3-bis(3,5-di-tert-butyl-2-hydroxyphenyl)benzimidazolin-2-ylidene (OCO), was synthesized and characterized by single-crystal X-ray diffraction, 1H nuclear magnetic resonance, infrared (IR) vibrational, ultraviolet/visible/near-infrared (UV/vis/NIR) electronic absorption, 57Fe Mössbauer, X-band electron paramagnetic resonance (EPR) and SQUID magnetization measurements. Complex 1 activates dioxygen to yield the diferric, μ-oxo-bridged complex [(OCO)Fe(py)(μ-O)Fe(O(C═O)O)(py)] (2) that was isolated and fully characterized. In 2, one of the iron-carbene bonds was oxidized to give a urea motif, resulting in an O(CNHC═O)O binding site, while the other Fe(OCO) unit remained unchanged. When the reaction is performed at -80 °C, an intensively colored, purple intermediate is observed (INT, λmax = 570 nm; ε = 5600 mol L-1 cm-1). INT acts as a sluggish oxidant, reacting only with easily oxidizable substrates, such as PPh3 or 2-phenylpropionic aldehyde (2-PPA). The identity of INT can be best described as a dinuclear complex containing a closed diamond core motif [(OCO)FeIV(μ-O)2FeIV(OCO)]. This proposal is based on extensive spectroscopic [UV/vis/NIR electronic absorption, 57Fe Mössbauer, X-band EPR, resonance Raman (rRaman), X-ray absorption, and nuclear resonance vibrational (NRVS)] and computational studies. The conversion of the diiron(II) complex 1 to the oxo diiron(IV) intermediate INT is reminiscent of the O2 activation process in soluble methane monooxygenases (sMMO). Most importantly, the low reactivity of INT supports the consensus that the [FeIV(μ-O)2FeIV] diamond core in sMMO is kinetically inert and needs to open up to terminal FeIV═O cores to react with the strong C-H bonds of methane.

Nd3+-Doped Scheelite-Type Multifunctional Materials-Their Thermal Stability and Magnetic Properties.

New Nd3+-doped cadmium molybdato-tungstates with the chemical formula of Cd1-3x▯xNd2x(MoO4)1-3x(WO4)3x (where x = 0.0283, 0.0455, 0.0839, 0.1430, 0.1875, 0.2000, 0.2500, and ▯ denotes a vacant site in the crystal lattice) were successfully synthesized by the high-temperature solid state reaction method, using CdMoO4 and Nd2(WO4)3 as the initial reactants. The structure and change in their lattice parameters as a function of Nd3+ ion concentration were investigated by the XRD (X-ray diffraction) method. The surface morphology and grain size of the doped materials were characterized by SEM (scanning electron microscopy). Their thermal properties and initial reactants were analyzed by DTA-TG (differential thermal analysis coupled with thermogravimetry) techniques. The optical properties of the Nd3+-doped cadmium molybdato-tungstates, such as optical band gap, were determined by UV-vis-NIR (ultraviolet-visible-near infrared) spectroscopy. The EPR (electron paramagnetic resonance) technique provided information on the type of magnetic interactions between Nd3+ ions.

Synthesis of Amphiphilic Polyacrylates as Peelable Coatings for Optical Surface Cleaning

Optical instruments require extremely high precision, and even minor surface contamination can severely impact their performance. Peelable coatings offer an effective and non-damaging method for removing contaminants from optical surfaces. In this study, an amphiphilic polyacrylate copolymer (PMLEA) was synthesized via solution radical copolymerization using the lipophilic monomer lauryl acrylate (LA) and hydrophilic monomers ER-10, methyl methacrylate (MMA), and butyl acrylate (BA). The structure and molecular weight of the copolymer were characterized using Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and gel permeation chromatography (GPC). The hydrophilic–lipophilic balance, surface tension, and wettability of the copolymer were analyzed through water titration, the platinum plate method, and liquid contact angle tests. The cleaning performance of the copolymer coating on quartz glass surface contaminants was evaluated using optical microscopy and Ultraviolet-Visible Near-Infrared (UV-Vis-NIR) spectroscopy. The study examined the effect of varying the ratio of LA to ER-10 on the hydrophilicity, lipophilicity, cleaning efficiency, and mechanical properties of the copolymer coating. The results showed that when the mass ratio of LA to ER-10 was 1:2, the synthesized copolymer exhibited optimal performance in removing dust, grease, and fingerprints from quartz glass surfaces. The coating had a tensile strength of 2.57 MPa, an elongation at break of 183%, and a peeling force of 2.07 N m−1.

Lycopene detection in cherry tomatoes with feature enhancement and data fusion

Lycopene, a biologically active phytochemical with health benefits, is a key quality indicator for cherry tomatoes. While ultraviolet/visible/near-infrared (UV/Vis/NIR) spectroscopy holds promise for large-scale online lycopene detection, capturing its characteristic signals is challenging due to the low lycopene concentration in cherry tomatoes. This study improved the prediction accuracy of lycopene by supplementing spectral data with image information through spectral feature enhancement and spectra-image fusion. The feasibility of using UV/Vis/NIR spectra and image features to predict lycopene content was validated. By enhancing spectral bands corresponding to colors correlated with lycopene, the performance of the spectral model was improved. Additionally, direct spectra-image fusion further enhanced the prediction accuracy, achieving RP2, RMSEP, and RPD as 0.95, 8.96 mg/kg, and 4.25, respectively. Overall, this research offers valuable insights into supplementing spectral data with image information to improve the accuracy of non-destructive lycopene detection, providing practical implications for online fruit quality prediction.

Annealing effects on 100 keV silicon negative ions implanted SiO2 thin films

SiO2 thin film of thickness 300 nm grown on p-type silicon substrate was implanted with 100 keV silicon negative ions for the fluences of 1 × 1016, 5 × 1016, and 1 × 1017 ions cm−2. The implanted samples were investigated using an energy-dispersive X-ray (EDX) spectroscopic technique, and the samples were annealed at a temperature of 900 oC under N2 ambient. Ultraviolet–visible near infrared (UV-Vis-NIR) spectroscopy has been used to investigate the implanted SiO2 thin film samples before and after thermal annealing. EDX results revealed an increase in the atomic percentage and weight percentage of silicon ions as compared to oxygen ions in SiO2 thin film. This may be due to the increase in the concentration of silicon ions with the increase of implanted ion fluences within the SiO2 thin film. UV-Vis-NIR studies showed higher transmittance for thermally annealed samples as compared to non-annealed samples. This may be attributed to the creation of a new SiOx phase in the SiO2 matrix at higher temperatures. UV-Vis-NIR studies also exhibited an increase in the energy band gap value after thermal annealing. This effect may be related to the formation of silicon nanoclusters in SiO2 thin film.

Waterborne polyurethane/cellulose composite aerogel with passive cooling and thermal insulation properties

AbstractPassive cooling is a cooling technology that does not require external energy input, with most passive cooling strategies having high manufacturing difficulty and cost. In this study, we prepared lightweight aerogels (0.093 g/cm3) with high porosity (91.3%), directional pores, enhanced elastic recovery performance, and lower thermal conductivity (0.046 W/mK) through simple mixing, directional freezing, and freeze‐drying. The prepared samples have a reflectance of 87% in the ultraviolet—visible—near‐infrared (UV‐Vis‐NIR) range (0.2–2.5 μm) and an emissivity of 93.6% in the atmospheric transparency window. After covering the box with axial and transverse aerogel samples, the temperature inside the box relative to the uncovered sample box decreased by 12.9 and 13.4°C, respectively. This work provides a feasible method for the research of simply prepared passive cooling materials.

Careful choice of carbonyl-containing cmps, and optimisation of Buchwald-Hartwig crosscoupling reaction conditions

In this study, new nitrogen-rich conjugated microporous polymers were synthesized using the Buchwald-Hartwig cross-coupling reaction. The synthesized polymers were characterized using various methods, including X-ray diffraction (XRD), ultraviolet-visible-near-infrared (UV-Vis-NIR) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, Brunauer-Emmett-Teller (BET) surface area analysis, and pore size distribution (PSD) determination using non-local density functional theory (NLDFT). The results provide important information about the structure and properties of synthesized materials, which contributes to a deeper understanding of their characteristics. The obtained characteristics of the material allow us to judge the quality and purity of the obtained polymers, which is important for further research, as well as serve as a basis for the development of new synthesis methods or improvement of existing technologies.

Design and fabrication of porous three‐dimensional Ag-doped reduced graphene oxide (3D Ag@rGO) composite for interfacial solar desalination

Solar-driven interfacial desalination technology has shown great promise in tackling the urgent global water scarcity crisis due to its ability to localize heat and its high solar-to-thermal energy conversion efficiency. For the realization of sustainable saline water desalination, the exploration of novel photothermal materials with higher water vapor generation and photothermal conversion efficiency is indispensable. In the current study, a novel 3D interconnected monolithic Ag-doped rGO network was synthesized for efficient photothermal application. The Ultraviolet–Visible-Near Infrared (UV–Vis-NIR) and FTIR analyses demonstrated that the controlled hydrothermal reduction of GO enabled the restoration of the conjugated sp2 bonded carbon network and the subsequent electrical and thermal conductivity through a significant reduction of oxygen-containing functional groups while maintaining the hydrophilicity of the composite photothermal material. In the solar simulated interfacial desalination study conducted using 3.5 wt.% saline water, the average surface temperatures of the 3D material increased from 27.1 to 54.7 °C in an hour, achieving an average net dark-excluded evaporation rate of 1.40 kg m−2 h−1 and a photothermal conversion efficiency of ~ 97.54% under 1 sun solar irradiance. In the outdoor real-world application test carried out, the surface temperature of the 3D solar evaporator reached up to 60 °C and achieved a net water evaporation rate of 1.50 kg m−2 h−1 under actual solar irradiation. The 3D interwoven porous hierarchical evaporator displayed no salt precipitation over the 54-h period monitored, demonstrating the promising salt rejection and real-world application potential for efficient desalination of saline water.

Ultraviolet–Visible-Near InfraRed spectroscopy for assessing metal powder cross-contamination: A multivariate approach for a quantitative analysis

The last few years have seen an increasing use of spherical metals powders to produce bulk parts through metal forming technologies like Additive Manufacturing and Metal Injection Molding. This, coupled with the wide availability of metal powders, leads to a critical issue: contamination across different systems in different process steps. Consequently, it is necessary to find a new, fast, and reliable analysis sensible to tiny traces of contamination. This work evaluates the applicability of Ultraviolet–Visible-Near InfraRed (UV–Vis-NIR) spectroscopy, a technique providing information on powders’ reflectance, for studying contaminated powders. This work focuses on assessing 3 binary systems obtained from the cross-contamination of 3 components (A92618, C10200 and S31603) in a low contamination range (from 0.5 vol% to vol. 6%) and in a high contamination range (25 vol% and vol.50%). After the UV–Vis-NIR analysis, multivariate analysis has been used to obtain quantitative results. Results show that, as the contamination level increases in the binary system, the shape of spectra changes and becomes progressively more similar to the contaminant one. The chemometric analysis allows the detection of the contaminant type and its concentration percentage in the contaminated powder.

Non-Destructive Prediction of the Mixed Mineral Pigment Content of Ancient Chinese Wall Paintings Based on Multiple Spectroscopic Techniques.

This study first developed non-destructive and accurate methods to predict the relative contents of mixed mineral pigments in ancient Chinese wall paintings using multiple spectroscopic techniques. The colorimetry, attenuated total reflection Fourier transform infrared spectroscopy (ATR FT-IR), ultraviolet-visible-near-infrared (UV-Vis-NIR) spectroscopy, and Raman spectroscopy were employed. Analyses were conducted including color difference, spectral reflection, ATR FT-IR spectra, and Raman mapping for simulated samples (malachite-lazurite mixed with rabbit glue samples) before and after aging. Models were then established for predicting the relative pigment contents of samples using UV-Vis-NIR and ATR FT-IR spectral data with Beer-Lambert law, and mathematical methods comprising principal component analysis (PCA) and nonlinear curve fitting. In particular, PCA and empty modeling methods combined with non-negative partial least squares were developed to predict the relative pigment contents based on Raman mapping data. The results demonstrated that approaches comprising PCA, mathematical model, and empty modeling based on the spectral data were effective at predicting the relative pigment contents. The predicted results obtained using the mathematical model based on UV-Vis-NIR spectra had an error of about 2%, and the best prediction based on ATR FT-IR spectra had an error of <3.6% at 1041 cm-1. The errors for the predictions using PCA and empty modeling based on Raman mapping data were 0.01-9.30% and 0.28-7.15%, respectively. However, the predicted relative pigment contents obtained based on ATR FT-IR data combined with the Beer-Lambert law had higher errors. The findings of this study confirm the strong feasibility of using spectroscopic techniques for quantitatively analyzing mixed mineral pigments.

Novel Au/Cu2NiSnS4 Nano-Heterostructure: Synthesis, Structure, Heterojunction Band Offset and Alignment, and Interfacial Charge Transfer Dynamics.

Considering the importance of physics and chemistry at material interfaces, we have explored the coupling of multinary chalcogenide semiconductor Cu2NiSnS4 nanoparticles (CNTS NPs) for the first time with the noble metal (Au) to form Au-CNTS nano-heterostructures (NHSs). The Au-CNTS NHSs is synthesized by a simple facile hot injection method. Synergistic experimental and theoretical approaches are employed to characterize the structural, optical, and electrical properties of the Au-CNTS NHSs. The absorption spectra demonstrate enhanced and broadened optical absorption in the ultraviolet-visible-near-infrared (UV-Vis-NIR) region, which is corroborated by cyclic voltammetry (CV) readings. CV measurements show type II staggered band alignment, with a conduction band offset (CBO) of 0.21 and 0.23 eV at the Au-CNTS/CdS and CNTS/CdS interface, respectively. Complementary first-principles density functional theory (DFT) calculations predict the formation of a stable Au-CNTS NHSs, with the Au nanoparticle transferring its electrons to the CNTS. Moreover, our interface analysis using ultrafast transient absorption experiments demonstrate that the Au-CNTS NHSs facilitates efficient transport and separation of photoexcited charge carriers when compared to pristine CNTS. The transient measurements further reveal a plasmonic electronic transfer from the Au nanoparticle to CNTS. Our advanced analysis and findings will prompt investigations into new functional materials and their photo/electrocatalysis and optoelectronic device applications in the future.

Double S-scheme Cu2−xSe/twinned-Cd0.5Zn0.5S homo-heterojunctions with surface plasmon effects for efficient photocatalytic H2 evolution

The enhancement of charge separation and utilization efficiency in both the bulk phase and interface of semiconductor photocatalysts, as well as the expansion of light absorption range, are crucial research topics in the field of photocatalysis. To address this issue, twinned Cd0.5Zn0.5S (T-CZS) homojunctions consisting of wurtzite Cd0.5Zn0.5S (WZ-CZS) and zinc blende Cd0.5Zn0.5S (ZB-CZS) were synthesized via a hydrothermal method to facilitate the bulk-phase charge separation. Meanwhile, Cu2−xSe with localized surface plasmon resonance effect (LSPR) generated by Cu vacancies was also obtained through a hydrothermal process. Due to their opposite electronegativity, a solvent evaporation strategy was employed to combine Cu2−xSe and T-CZS by intermolecular electrostatic. After optimization, the photocatalytic hydrogen (H2) evolution rate of 5 wt% Cu2−xSe/T-CZS reached an impressive value of 60 mmol∙h−1∙g−1, which was 4.6 and 66.6 times higher than that of pure Cu2−xSe and T-CZS, respectively. Furthermore, this composites demonstrated a remarkable rate of 0.46 mmol∙h−1∙g−1 under near-infrared (NIR) wavelength (>800 nm). The enhanced performance observed in Cu2−xSe/T-CZS can be attributed to its unique and efficient double S-scheme charge transfer mechanism which effectively suppresses rapid recombination of electron-hole pairs both within the bulk phase and at the surface interfaces; this conclusion is supported by Density Functional Theory (DFT) calculations as well as electron paramagnetic resonance spectroscopy analysis. Moreover, incorporation of Cu2−xSe enables effective utilization ultraviolet visible-near infrared (UV–Vis-NIR) light by the composites while facilitating injection “hot electrons” into T-CZS for promoting photocatalytic reactions. This study provides a potential strategy for achieving efficient solar energy conversion through synergistic integration of non-stoichiometric plasmonic materials with photocatalysts with twinned-twinned structures.

New methods for the identification of malachite pigments with varying particle sizes used in ancient Chinese murals by spectroscopic techniques

This study attempts to propose a simple, low-interventive and higher accuracy identification method for malachite pigments with varying particle sizes based on attenuated total reflection-Fourier transform infrared (ATR-FTIR), and evaluate the accuracy of ATR-FTIR and ultraviolet–visible near-infrared (UV-VIS-NIR) spectroscopy for identifying particle sizes. The micro-morphology, particle size, colour difference, and spectral characteristics of the malachite samples were determined using scanning electron microscopy (SEM), laser particle size analysis, colourimetry, UV-VIS-NIR and ATR-FTIR spectrometry. The principal component analysis (PCA) and mathematical models based on nonlinear curve fitting using UV-VIS-NIR and FTIR spectral data were developed and evaluated for the particle size identification of various malachite samples (pure malachite samples, fresh and aged malachite-rabbit glue samples). SEM morphological results showed that the malachite pigments with smaller particle sizes appear to have irregular flakes with a few loose agglomerated granules attached to the surface. The weight-specific surface area also increased gradually as the pigment particle size decreased. The colour difference results revealed that smaller malachite particle size gradually shifted toward the red–blue regions in CIE L*a*b* colour space. In addition, more intense reflectance and IR spectral absorbance peaks were observed in the case of the smaller particle size. The above proposed methods of particle size identification proved to be highly feasible and effective in predicting pigment particle size, which were confirmed by the PCA identification results and the mathematical model. Also, ATR-FTIR spectroscopy could provide more accurate predictions than UV-VIS-NIR spectroscopy, by keeping prediction errors below 5.5 μm.

Crystal Structure and Optical Properties Characterization in Quasi-0D Lead-Free Bromide Crystals (C6H14N)3Bi2Br9·H2O and (C6H14N)3Sb3Br12.

Low dimensional organic inorganic metal halide materials have shown broadband emission and large Stokes shift, making them widely used in various fields and a promising candidate material. Here, the zero-dimensional lead-free bromide single crystals (C6H14N)3Bi2Br9·H2O (1) and (C6H14N)3Sb3Br12 (2) were synthesized. They crystallized in the monoclinic crystal system with the space group of P21 and P21/n, respectively. Through ultraviolet-visible-near-infrared (UV-vis-NIR) absorption analysis, the band gaps of (C6H14N)3Bi2Br9·H2O and (C6H14N)3Sb3Br12 are found to be 2.75 and 2.83 eV, respectively. Upon photoexcitation, (C6H14N)3Bi2Br9·H2O exhibit broad-band red emission peaking at 640 nm with a large Stokes shift of 180 nm and a lifetime of 2.94 ns, and the emission spectrum of (C6H14N)3Sb3Br12 are similar to those of (C6H14N)3Bi2Br9·H2O. This exclusive red emission is ascribed to the self-trapping exciton transition caused by lattice distortion, which is confirmed through both experiments and first-principles calculations. In addition, due to the polar space group structure and the large spin-orbit coupling (SOC) associated with the heavy elements of Bi and Br of crystal 1, an obvious Rashba effect was observed. The discovery of organic inorganic metal bromide material provides a critical foundation for uncovering the connection between 0D metal halide materials' structures and properties.

Integration of One-Dimensional (1D) Lead-Free Perovskite Microbelts onto Silicon for Ultraviolet-Visible-Near-Infrared (UV-vis-NIR) Heterojunction Photodetectors.

Lead-free perovskites are considered to be candidates for next-generation photodetectors, because of their excellent charge carrier transport properties and low toxicity. However, their application in integrated circuits is hindered by their inadequate performance and size restrictions. To aim at the development of lead-free perovskite-integrated optoelectronic devices, a CsAg2I3/silicon (CAI/Si) heterojunction is presented in this work by using a spatial confinement growth method, where the in-plane growth of CAI microbelts with high-quality single-crystal characteristics is primarily dependent on the concentration of surrounding precursor solution. The fabricated photodetectors based on the CAI/Si heterojunctions exhibit a broad-spectrum detection capability in the ultraviolet-visible-near-infrared (UV-vis-NIR) range. In addition, the photodetectors show good photoelectric detection performance, including a maximum responsivity of 48.5 mA/W and detectivity of 1.13 × 1011 Jones, respectively. Besides, the photodetectors have a rapid response of 6.5/224 μs and good air stability for over 2 months. This work contributes a new idea to design next-generation optoelectronic devices with high integration density.

On the preparation and spectroelectrochemical characterization of certain 2,5‐bis(het)aryl substituted thiophenes

AbstractIn this work, a series of novel 2,5‐bis(het)aryl and 2,5‐bis‐thienyl substituted thiophenes have been synthesized and characterized by ultraviolet‐visible‐near infrared (UV‐Vis‐NIR) absorption and fluorescence spectroscopy as well as cyclic voltammetry. From the electron paramagnetic resonance (EPR)/UV‐Vis‐NIR spectroelectrochemical data, information about the optical and magnetic properties of the charged species of these compounds have been provided. The spin distributions in the electrochemically generated radical ions were estimated experimentally and compared with theoretical data.

High‐performance Self‐powered Ultraviolet‐visible‐near infrared Broadband Photodetectors Based on Sb2Se3/TiO2 Heterojunctions and Multifunctional Applications

AbstractHigh‐performance broadband photodetectors (PDs) are essential components in spectroscopy, remote sensing, imaging, and light communication applications. In this paper, Sb2Se3 nanoparticles (NPs) are uniformly deposited on TiO2 nanorod arrays (NRs) to construct a type II heterojunction with good interfacial contact by a simple two‐step potentiostatic electrochemical deposition method combined with N2 atmosphere annealing at 280, 290 and 300 °C to control the amount of Se in Sb2Se3. A good interfacial contact between Sb2Se3 and TiO2 is conducive to the separation and transport of photogenerated carriers. Sb2Se3/TiO2 PDs exhibit excellent self‐powered photoresponse in a broad spectral range from ultraviolet‐visible‐near infrared (UV‐VIS‐NIR) due to the combined effects of high light absorption, low defect density, and more suitable band alignment. The optimal parameters with a responsivity of 13.48 A W−1, detectivity of 7.9 × 1011 Jones, and response time of 18/20 µs are demonstrated for the PDs annealed at 290 °C. The excellent performance broadband Sb2Se3/TiO2 PDs are used to construct the application models in the light communication for light encryption and flaw detection. This work opens up a new strategy for Sb2Se3/TiO2 PDs in multifunctional applications.