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White light emitting thermally stable bismuth phosphate phosphor Ca <sub/>3</sub> Bi( <scp>PO</scp><sub/>4</sub> ) <sub/>3</sub> :Dy <sup>3+</sup> for solid state lighting applications
摘要： White light emitting dysprosium doped Ca3Bi(PO4)3 phosphor was successfully synthesized via co-precipitation method for the first time and the structural, vibrational, morphological and luminescent properties have been investigated for solid state lighting applications. The X-ray diffraction (XRD) and structural refinement studies reveal that the synthesized phosphors consist of single phase with cubic structure. The field emission scanning electron microscopy (FE-SEM) images reveal that the as-synthesized phosphor has micron size with an irregular shape. Under near ultraviolet (n-UV) and blue excitation, the phosphor exhibits white light emission via a combination of blue (~451 nm) and yellow (~575 nm) emission bands. The optimized concentration of Dy3+ ions is 6.0 mol % after which the concertation quenching takes place. The process of energy transfer between Dy3+ ions is due to dipole-dipole interaction, which was confirmed by applying Dexter and Reisfeld’s Energy Transfer (ET) formula. The CIE chromaticity coordinates for the optimized phosphor were (0.329, 0.377), which lie in the white light region. The emission intensity remains to 83.41% at 373 K to that of at room temperature, which indicates good thermal stability. The above mentioned results demonstrate that Ca3Bi(PO4)3 is a potential phosphor for solid state lighting applications.
关键词： White LEDs,Structural and luminescent properties,White light emission,Phosphor,Thermally stable
更新于2025-11-21 11:18:25
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Cross-linking induced thermoresponsive hydrogel with light emitting and self-healing property
摘要： Development of self-healing hydrogels with thermoresponse is very important for artificial smart materials. In this article, the self-healing hydrogels with reversible thermoresponse were designed through cross-linking-induced thermoresponse (CIT) mechanism. The hydrogels were prepared from ketone group containing copolymer bearing tetraphenyl ethylene (TPE) and cross-linked by naphthalene containing acylhydrazide cross-linker. The mechanical property, light emission, self-healing, and thermo-response of the hydrogels were investigated intensively. With regulation of the copolymer composition, hydrogels showed thermoresponse with the LCST varied from above to below body temperature. At the same time, the hydrogels showed self-healing property based on the reversible characteristic of the acylhydrazone bond. The hydrogel also showed temperature-regulated light emission behavior based on AIE property of the TPE unit.
关键词： TPE,cross-linking-induced thermoresponse,hydrogel,self-healing,light emission
更新于2025-11-14 15:27:09
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Cross-linking induced thermo-responsive self-healable hydrogels with temperature regulated light emission property
摘要： Self-healing hydrogels draw great attentions in past decade based on the self-healing property similar to living creatures and their potential application in bioscience. On the other hand, thermo-response of the hydrogel endow the hydrogel with smart characteristic for controlled drug loading and delivery, diagnosis, cell imaging, life simulation, etc. In this study, self-healable hydrogel with cross-linking induced thermo-response (CIT) property was prepared from TPE containing copolymer TPE-P(DMA-stat-DAA) and the LCST of the hydrogels could be regulated by copolymer composition and the structure of the cross-linkers. The light emission property, mechanical and self-healing performances of the hydrogels are also investigated intensively. The results showed the LCST of the hydrogels could be regulated to body temperature through cross-linking induced thermo-response (CIT) mechanism with PEO23 DNH cross-linking. At the same time, the hydrogels exhibit light emission property, excellent self-healing ability and good mechanical properties. Moreover, the hydrogels showed different light emission property regulated by temperature based on AIE property of the TPE.
关键词： Light emission,Self-healing hydrogel,Cross-linking induced thermo-response
更新于2025-11-14 15:26:12
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Highly efficient transparent nanophosphor films for tunable white light-emitting layered coatings
摘要： Bright luminescence in rare-earth (RE) nanocrystals, so-called nanophosphors, is generally achieved by choosing a host that enable the effective excitation of the RE activator through charge or energy transfer. Although tungstate, molybdate or vanadate compounds provide the aforementioned transfer, a comparative analysis of the efficiency of such emitters remains elusive. Herein we perform a combined structural and optical analysis, which reveals that the tetragonal GdVO4 matrix gives rise to the highest efficiency among the different transparent nanophosphor films compared. Then we demonstrate that by sequential stacking of optical quality layers made of Eu3+ and Dy3+ doped nanocrystals, it is possible to attain highly transparent white light emitting coatings of tunable shade with photoluminescence quantum yields above 35%. Layering provides precise dynamic tuning of the chromaticity based on the photoexcitation wavelength dependence of the emission of the nanophosphor ensemble without altering the chemical composition of the emitters or degrading their efficiency. Total extinction of incoming radiation along with the high quantum yields achieved make these thin layered phosphors one of the most efficient transparent white converter coatings ever developed.
关键词： rare-earth nanocrystals,transparent coatings,nanophosphors,phosphor materials,white-light emission
更新于2025-11-14 15:23:50
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Design and characterization of small detection modules based on scintillators and WLS bars with SiPM readout for a cosmic ray mini-array
摘要： This paper describes the design and characterization tests of detection modules for a low-cost, easily reconfigurable mini-array for cosmic rays. The basic layout of each individual module is based on a 400 cm2 scintillator tile, optically coupled to a Wavelength Shifter (WLS) bar and a Silicon Photomultiplier (SiPM) for light collection and readout. Low cost solutions, based on the Arduino MEGA board, have been adopted for electronics, triggering and data acquisition, in view of the operation of this facility. The first detection modules, equipped with 4×4 mm2 SiPMs were fully built and characterized. Additional tests were also carried out with photosensors having different sensitive area and technology.
关键词： Scintillators, scintillation and light emission processes (solid, gas and liquid scintillators),Particle detectors,Interaction of radiation with matter
更新于2025-09-23 15:23:52
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A multi-color and white-light emissive cucurbituril/terpyridine/lanthanide supramolecular nanofiber
摘要： Multi-color and white light luminescence materials based on supramolecular assemblies are attractive because of their potential applications in advanced light-emitting material. Herein, a cucurbit[8]uril-enhanced lanthanide luminescent supramolecular assembly was constructed in a facile but efficient way using terpyridine imidozalium cations, cucurbit[8]urils and rare earth ions such as Tb3+ and Eu3+. Significantly, the resultant fibrous supramolecular assembly, with an average width of 15 nm, could emit remarkable lanthanide luminescence, which was ten times higher than the corresponding terpyridine/Ln3+ without cucurbit[8]uril. And the solid state luminescence of supramolecular assembly could be smartly and easily turned among blue, green, red and white by adjusting the molar ratios between Tb3+ and Eu3+. The enhanced white-light emission by supramolecular strategy may provide a new approach for smart and tunable solid luminescent materials.
关键词： Cucurbit[8]uril,White-light emission,Supramolecular chemistry,Host-guest interaction,Lanthanide luminescence
更新于2025-09-23 15:23:52
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Light emitting self-healable hydrogel with bio-degradability prepared form pectin and Tetraphenylethylene bearing polymer
摘要： Self-healable hydrogel have wide applications in bioscience. In this research, self-healable hydrogel were prepared from TPE-[P(DMA-stat-DAA)]2 and acylhydrazide functionalized pectin. The TPE containing polymer endowed the hydrogel with light emission property while the pectin make the hydrogel biodegradable. Results showed that the pectin acylhydrazide can be prepared conveniently from pectin through hydrazinolysis. Light emissive hydrogels formed and self-healed without additional stimulus. More importantly, the hydrogel become light emitting with PL intensity higher than the polymer solution. The reason for this result is because the TPE units aggregated in the hydrophobic pectin ring and triggered AIE property. With biodegradable pectin, the hydrogel could be degraded naturally without worrying about the toxicity of the hydrogel in future bio-applications.
关键词： Self-healing,Hydrogel,TPE,Pectin,Light emission
更新于2025-09-23 15:23:52
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Blue Electrogenerated Chemiluminescence from Halide Perovskite Nanocrystals
摘要： Electrogenerated chemiluminescence (ECL) has been extensively used in ultrasensitive electroanalysis because it can be generated electrochemically without using expensive optics and light sources. Visible ECL emission can be obtained with a reasonable quantum yield and stability. Blue ECL is rare and often suffers from stability and poor quantum efficiency. Blue ECL emission at 473 nm from organometallic halide perovskite nanocrystals (PNCs), CH3NH3PbCl1.08Br1.92, is reported here for the first time using tripropylamine (TPrA) as co-reactant. The blue ECL emission peak resembles its photoluminescence peak position. In addition to this blue emission peak, the ECL spectra of CH3NH3PbCl1.08Br1.92 PNCs also showed a broad ECL peak at 745 nm. Generation of the second ECL peak at 745 nm from CH3NH3PbCl1.08Br1.92 PNCs was can be explained by the existence of surface trap states on as-synthesized PNC due to incomplete surface passivation. Halide anion tunability of ECL emission from CH3NH3PbX3 (X: Cl, Br, I) PNCs is also demonstrated. The fluorescence microscopy image of single PNC and stability of selected single PNCs are presented in this with simultaneous acquisition of fluorescence spectra using 405-nm laser excitation. The photoluminescence (PL) decay was described by PL lifetime (τ) of 1.2 ns. The effect of the addition of surfactants (oleic acid and n-octylamine) on the fluorescence intensity and stability of CH3NH3PbCl1.08Br1.92 PNCs is also discussed.
关键词： Surfactants,Blue light emission,ECL (electrogenerated chemiluminescence),Photoluminescence (PL),Perovskite nanocrystals (PNCs),Photoluminescence quantum yield (PLQY)
更新于2025-09-23 15:23:52
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Polymers with Exceptional Photoluminescence by Homoconjugation
摘要： Commonly, photoluminescence in organic polymers relies on π-electron delocalization by alternating double and single bonds. Remarkably, however, poly(phenylene methylene) (PPM) and methyl-substituted derivatives, such as those shown in Fig.1a, exhibit fluorescence in the wavelength region of 400–600 nm which cannot be explained by such systems of delocalized electrons. Instead, the results of extended investigations are in line with homoconjugation as the origin of the photoluminescence between 400 nm and 600 nm. Homoconjugation only arises in special chemical structures for which conjugation across individual π-electron systems can occur despite those systems being separated by an electronically insulating group, e.g. a methylene group. Such a conjugation is enabled by the overlap of p-orbitals in PPM (and derivatives), as schematically illustrated in Fig. 1b. DFT calculations for PPM indicate that homoconjugation is indeed energetically favorable. Note that homoconjugation in PPM and its derivatives can only be effective in certain conformations of the polymer chains, such as that displayed in Fig. 1b. For example, it appears that the conformations in the as-synthesized materials, which were finally obtained by rapid precipitation, are frozen in non-optimal geometries for homoconjugation because absorption and fluorescence intensity for such samples markedly increase following annealing above the glass transition temperature (66 °C for PPM; onset of thermal decomposition by TGA at 470 °C). Fluorescence of PPM and its derivatives is observed in the solid (Fig. 1c) as well as in the dissolved states. The polymers were extensively studied by UV-vis absorption spectroscopy, photoluminescence excitation spectroscopy and cyclovoltammetry. The HOMO-LUMO gap of 3.2–3.3 eV corresponds to an onset of optical absorption at approximately 375–390 nm, i.e. at higher wavelengths than expected for isolated phenylene groups. This is in agreement with homoconjugation for which electron delocalization occurs over several phenylene units. Further to this, the observed peak shifts of photoluminescence spectra towards higher wavelengths with increasing degree of polymerization (DP), up to DP ≈ 10, are fully consistent with electron delocalization along the polymer backbone. The photoluminescence lifetime recorded for thin PPM films is remarkably high, namely 8.55 ns. The photoluminescence quantum efficiency in solutions amounts to 69% and in films to 41%; notably the latter value is comparable to those for high-performance π-conjugated polymers. Interestingly, however, the absorption coefficient of PPM, measured for thick films, amounted to 80 cm–1 which, for comparison, is about 2600 times lower than the value of poly(dioctylfluorene). Notably, π-stacking, aggregation/crystallization and impurities were excluded as the origins of fluorescence in the course of the extended investigations. We expect that poly(phenylene methylene) and its derivatives will serve as examples of a new class of fluorescent polymers characterized by homoconjugation along the main chain.
关键词： Optical spectroscopy,Fluorescence,Homoconjugation,Poly(phenylene methylene)s,Light emission
更新于2025-09-23 15:22:29
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Highly Stretchable Carbon Nanotube Fibers with Tunable and Stable Light Emission
摘要： Carbon nanotubes (CNTs) possess intriguing photoluminescence properties, and CNT fibers emit strong incandescent light thus act as macroscopic light sources. So far, straight-shaped CNT fibers are a focus of study and their emission properties are elucidated. Here, the authors show that helical-shaped single-walled carbon nanotube (SWNT) fibers produce uniform and stable incandescent light along the entire fiber under moderate voltages, and the emission intensity is tailored over a wide range by the applied voltage and the elongation of the fiber (up to 70% strain), and in a reversible way during mechanical deformation. Their highly stretchable SWNT fibers with tunable light emission have promising applications in emerging research areas such as wearable electronics and high-performance optoelectronic fiber systems.
关键词： single-wall carbon nanotubes,stretchable device,helical fiber,light emission
更新于2025-09-23 15:22:29