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A Single Non-blinking Cs4PbBr6 Nanoparticle as a Nano-thermometer
摘要： Inorganic perovskite materials have attracted broad interest in the last several years due to their stability and promising applications as photovoltaic and light-emitting materials. In this work, we prepared Cs4PbBr6 nanoparticles showing stable photoluminescence (PL) without blinking and studied the PL properties of individual Cs4PbBr6 nanoparticles in the biology temperature range. We found that both PL intensity and lifetime of a single Cs4PbBr6 particle strongly depends on the temperature. The PL intensity and lifetime decrease almost linearly with the increasing of the temperature. The slope of the PL intensity and lifetime versus temperature were as high as 2% and 3% per degree centigrade, respectively. The photo stability and thermal stability were also checked for individual particles. With these results, we proposed that the sensitivity of PL intensity and lifetime of a single Cs4PbBr6 nanoparticle on temperature showed the potential application of a single particle as a nano-thermometer for thermal detection in a local environment.
关键词： Cs4PbBr6,Thermometer,Perovskite,Photoluminescence,Nanoparticle
更新于2025-09-23 15:23:52
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Superior photocatalytic activity of tungsten disulfide nanostructures: role of morphology and defects
摘要： Tungsten disulphide (WS2) nanostructures, WS2 nanosheets (WNS) and WS2 nanorods (WNR), were synthesized by varying the surfactant, N-cetyl-N,N,N-trimethyl ammonium bromide (CTAB), concentration using facile hydrothermal technique. Samples were characterized by high-resolution transmission electron microscopy (HRTEM) and field emission scanning electron microscopy (FESEM) for morphology, X-ray diffraction (XRD) to confirm their phase and crystal structure, photoluminescence (PL) and Raman studies for the determination of defect density, Tauc plot for the determination of band gap, Fourier transform infra red (FTIR) spectroscopy for functional groups and bonds, and Brunauer–Emmett–Teller (BET) isotherms for the determination of pore size and surface area. A comparative study using WS2 nanostructures (WNS and WNR) was conducted to observe the photocatalytic degradation efficiency (?) and degradation kinetics on methylene blue (MB) and 4-chlorophenol (4-CP). The superior photocatalytic performance of WNS over WNR is attributed to enhanced pore size and reduced defect density. High-performance liquid chromatography was carried out for the determination of intermediate products during photocatalytic degradation.
关键词： Raman,High-performance liquid chromatography,WS2 nanostructures,Photoluminescence,Photocatalysis
更新于2025-09-23 15:23:52
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Fabrication of alkali metal sulfate–doped zinc tungstate and their photoluminescence
摘要： The enhancement of photoluminescence of alkali metal sulfate-doped zinc tungstate was investigated. All samples were prepared by solid-state reaction at 800 °C using ZnO, WO3, and alkali metal sulfates as starting powders. The zinc tungstate phase was confirmed from the samples by X-ray diffraction. The emission peak of the samples excited at 275 nm was observed at 465 nm. Rb2SO4 > K2SO4 > Cs2SO4 > undoped > Na2SO4 > Li2SO4 was the order of peak emission intensity of alkali metal sulfate-doped samples. Alkali metals with a large ionic radius (K, Rb, Cs) enhanced the emission of intrinsic luminescence in the blue wavelength region. Moreover, sulfates had the potential to change the luminescence activities of the samples.
关键词： Solid-state reaction,Alkali metal,Zinc tungstate,Sulfate,Photoluminescence
更新于2025-09-23 15:23:52
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Characterization, optical and luminescence features of cobalt ions in multi-component PbO Al2O3TeO2GeO2SiO2 glass ceramics
摘要： Glass ceramics of the composition PbOeAl2O3eTeO2eGeO2eSiO2 doped with CoO (ranging between 0 and 1.0 mol %) were prepared by melt quenching technique followed by heat treatment. The techniques such as XRD, SEM, EDS and DTA were employed for the characterization of the prepared samples. Conventional spectroscopic studies viz., optical absorption, photoluminescence, FTIR and Raman were also performed on these samples. The optical absorption spectra of the titled glass ceramics exhibited two principal absorption bands, one at about 594 nm and the second one consisting of multiplets with the meta centre at about 1455 nm ascribed to the 4A2 (4F) → 4T1 (4P) and 4A2 (4F) → 4T1 (4F) transitions of tetrahedrally coordinated Co2+ ions, respectively. Besides these, the spectra also exhibited two feeble bands at about 532 and 643 nm which are the characteristics of octahedrally coordinated Co2+ and Co3+ ions, respectively. Using Tanabe Sugano diagram the crystal field splitting parameter Dq, Racah parameters B, C and nephelauxetic ratio, β were evaluated for Co2+ ions. The photoluminescence spectra of the titled glass ceramics have exhibited two broad emission bands at 628 and 870 nm ascribed to 4T1 (4P) → 4A2 (4F) and 4T1 (4P) → 4T2 (4F) tetrahedral transitions of Co2+ ions, respectively. FTIR and Raman spectra of the titled samples exhibited various asymmetrical and symmetrical vibrational bands due to viz., silicate, germanate, PbO4, PbO6, AlO6, TeO4, TeO3 and CoIIIeO vibrations in the glass ceramic matrix. The spectroscopic investigations on the titled glass ceramics have revealed that if CoO is present in small quantities the cobalt ions predominantly occupy the octahedral sites in the glass network, whereas the tetrahedrally coordinated Co2+ ions are found to increase if the concentration of nucleating agent CoO is gradually increased up to 1.0 mol%. As a result the degree of depolymerization of the glass network decreases which in turn enhances its rigidity with increasing the concentration of nucleating agent CoO. From these investigations we report that the glass ceramics doped with 1.0 mol% of CoO are suitable for insulating devices as well as for photonic devices.
关键词： Photoluminescence,Raman spectra,XRD,Multi-component glass ceramics,SEM,Optical absorption,Cobalt ions
更新于2025-09-23 15:23:52
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Enlightening developments in 1,3-P,N-ligand-stabilized multinuclear complexes: A shift from catalysis to photoluminescence
摘要： 1,3-P,N-ligands provide the ideal spatial separation to facilitate homo and hetero metal-metal interactions to access multinuclear complexes. The rich chemistry of such complexes includes applications in coordination chemistry, metal-activation and (cooperative) catalysis. However, it has been especially the fruitful combination in photoluminescent P,N-coinage metal complexes which has renewed interest in these ligands. While the field classically focused on dinuclear species, now also coinage metal clusters have been studied for use in catalysis and photophysical applications. Reviewed are recent developments from 2009 to mid-2017.
关键词： P,N-ligands,Coinage metal clusters,Photoluminescence,Transition metal complexes,Homogeneous catalysis,Metal-metal bonds
更新于2025-09-23 15:23:52
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Ethanothermal synthesis of phenol-derived carbon dots with multiple color emission via a versatile oxidation strategy
摘要： Herein, we report an ethanothermal synthesis of multicolor fluorescent carbon dots (CDs) by using a series of phenols and oxidants as the precursors. The emission colors of CDs are well-controlled at blue, green, yellow or red wavelengths by adjusting the combination of a phenol and an oxidant. And the naphthalenediol with highly reactivity and the oxidant with heavy halogen atom result in CDs exhibiting long wavelength emission. The resulting nanodots are characterized as amorphous aggregates with abundant oxygen species. The phenol-derived CDs can be used as highly processible fillers to fabricate epoxy composites, and a white light-emitting diode (LED) employing the multicolor CDs/epoxy composite as the light converter is also demonstrated.
关键词： Carbon dots,Photoluminescence,Phenols
更新于2025-09-23 15:23:52
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A highly efficient fluorescent material based on rare-earth-modified polyhydroxyalkanoates
摘要： Fluorescent materials play an important role in biomedical fields. However, the main types of fluorescent materials suffer from several disadvantages especially the biotoxicity, which largely restrict its wider applications in biological fields. In this study, a highly efficient rare-earth-modified fluorescent material was successfully designed and fabricated based on polyhydroxyalkanoates, which are known as biodegradable and biocompatible material. A new Functional-PHA polymer was microbially synthesized by engineered Halomonas bluephagenesis and was used as a basal matrix to generate the rare-earth-modified PHA. N-acetyl-L-cysteine-grafted PHA (NAL-grafted-PHA) was first produced via a UV-initiated thiol-ene click reaction and the rare earth metal ions (Eu3+ and Tb3+) were subsequently chelated onto the NAL-grafted-PHA through the coordination effect. The composite material exhibited intense photoluminescence properties under UV laser excitation, indicating the excellent features as fluorescent material. The enhanced hydrophilicity and superior biocompatibility of rare earth-chelated PHA were confirmed, suggesting its great potential application value in biomedical fields.
关键词： Halomonas,photoluminescence,next generation industrial biotechnology,fluorescent material,polyhydroxyalkanoates,PHB,Rare-earth metal ions
更新于2025-09-23 15:23:52
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Growth Order-Dependent Strain Variations of Lateral Transition Metal Dichalcogenide Heterostructures
摘要： Understanding the heterojunction of a lateral heterostructured transition metal dichalcogenide (hTMD) is important to take advantage of the combined optoelectronic properties of individual TMDs for various applications but, however, is hampered by mingled effects from lattice mismatch and substrate interaction. Here, we systematically investigated the strain occurring at lateral hTMDs consisting of molybdenum disulfide (MoS2) and molybdenum diselenide (MoSe2) prepared by chemical vapor deposition. Comparison of homologous TMDs and hTMDs from controlled growth order revealed systematic change in photoluminescence behavior depending on substrate interaction and relative lattice mismatch. Near the heterojunction, a TMD with a larger lattice constant (a) exhibits photoluminescence (PL) red-shift, whereas a TMD with smaller a shows an opposite trend owing to lattice-induced strain. These effects are augmented in a subtractive or additive manner by tensile strain from the substrate interaction. Moreover, comparison of PLs revealed that the shell region grown from the core edges exhibits weak substrate interaction contrasted by that of a shell region independently grown on a shell. This study provides detailed understandings of the heterojunction at a lateral hTMD for various applications.
关键词： photoluminescence,lateral heterostructure,strain,transition metal dichalcogenides,chemical vapor deposition
更新于2025-09-23 15:23:52
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Mechanism of photoluminescence intermittency in organic-inorganic perovskite nanocrystals
摘要： Lead halide perovskite nanocrystals have demonstrated their potential as active materials for optoelectronic applications over the past few years. Nevertheless one issue which hampers their applicability has to do with the observation of photoluminescence intermittency, commonly referred to as blinking, as in their inorganic counterparts. Such behavior, reported for structures well above the quantum confinement regime, has been discussed to be strongly related with the presence of charge carrier traps. In this work we analyze the characteristics of this intermittency and explore the dependence with the surrounding atmosphere, showing evidence for the critical role played by the presence of oxygen. We discuss a possible mechanism in which a constant creation/annihilation of halide-related carrier traps takes place under light irradiation, the dominant rate being determined by the atmosphere.
关键词： photoluminescence,Hybrid organic inorganic perovskites,spectroscopy,nanocrystal,blinking
更新于2025-09-23 15:23:52
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Photoluminescence carbon dot as a sensor for detecting of Pseudomonas aeruginosa bacteria: Hydrothermal synthesis of magnetic hollow NiFe2O4-carbon dots nanocomposite material
摘要： The purpose of this research is synthesis of photoluminescence nanoparticles for detection of Pseudomonas aeruginosa that is feasible for bio medial applications. Carbon nano-templates were prepared from soot by burning of almond as a green precursor. Then NiFe2O4 nanoparticles were synthesized on the carbon templates. For preparation of hollow structures, the product was calcinated for removing of carbon templates. Finally, carbon dots were synthesized on the hollow nickel ferrite cores by applying ethylene diamine and citric acid. Phase of the products was approved by X-ray diffraction (XRD), scanning electron microscopy (SEM) depict the morphology and transmission electron microscopy (TEM) probe the grain size and hollow structures of the nickel ferrite, carbon dot and nanocomposites. Fourier transform infrared (FT-IR) spectroscopy approved the purity of the nanostructures. Ultraviolet-visible (UV-Vis) absorption and photo-luminescence (PL) spectroscopy confirmed appropriate photo-luminescence under ultraviolet irradiation. Vibrating sample magnetometer (VSM) shows ferromagnetic property of the both hollow NiFe2O4 and nickel ferrite-carbon nanocomposite. This work presents a new nanostructure as green prepared photoluminescence sensor for detecting of Pseudomonas aeruginosa bacteria, lead and mercury ions. Outcomes confirm decreasing in photoluminescence intensity of the nanocomposite by enhancing of Pseudomonas aeruginosa, Pb(II) and Hg(II) ions. Antibacterial effect of NiFe2O4-carbon dot on the degradation of Pseudomonas aeruginosa bacteria was also examined.
关键词： Nanostructures,Carbon Dots,Magnetic,Photoluminescence,P. Aeruginosa Bacteria
更新于2025-09-23 15:23:52