- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Temperature-dependent photoluminescence of pure and Mn-doped CsPbCl3 nanocrystals
摘要： Temperature-dependent photoluminescence (PL) properties of Mn-doped CsPbCl3 nanocrystals (NCs) are studied and compared with pure CsPbCl3 NCs by use of steady-state and time-resolved PL spectroscopies. The intrinsic exciton PL of the CsPbCl3 NCs locates at the wavelength range from 405 to 410 nm. The PL intensity in this range decreases rapidly, and the bandgap and linewidth become wider with rising temperature from 78 to 350 K. It is found that the exciton PL shows biexponential kinetics. The short-lived emission is ascribed to the surface trapping state recombination in NCs that has a photoinduced trapped pathway and a temporally resolved peak shift. The long-lived component is due to the band-edge excitonic recombination. Mn dopant open a new emission window at the wavelength range from 560 to 680 nm, of which intensity increases from 140 to 270 K, and then decreases with rising temperature up to 350 K. This unusual temperature dependence is ascribed to the thermal-assisted transition from the excitonic state of NCs to the 4T1 energy level of Mn2+. This work shows the potential of transition metal element doped perovskite NCs that can take advantage of the coupling between excitons and the d electrons of the dopants for expanded functionalities, such as temperature sensor and light-emitting diode.
关键词： Photoluminescence,Band-edge exciton,CsPbCl3,Mn-doped,Nanocrystals
更新于2025-11-25 10:30:42
-
Fluorescence spectra of colloidal self-assembled CdSe nano-wire on substrate of porous Al <sub/>2</sub> O <sub/>3</sub> /Au nanoparticles
摘要： We present a self-assembly method to prepare array nano-wires of colloidal CdSe quantum dots on a substrate of porous Al2O3 film modified by gold nanoparticles. The photoluminescence (PL) spectra of nanowires are in situ measured by using a scanning near-field optical microscopy (SNOM) probe tip with 100-nm aperture on the scanning near-field optical microscope. The results show that the binding sites from the edge of porous Al2O3 nanopores are combined with the carboxyl of CdSe quantum dots’ surface to form an array of CdSe nanowires in the process of losing background solvent because of the gold nanoparticles filling the nano-holes of porous Al2O3 film. Compared with the area of non-self-assembled nano-wire, the fluorescence on the Al2O3/Au/CdSe interface is significantly enhanced in the self-assembly nano-wire regions due to the electron transfer conductor effect of the gold nanoparticles’ surface. In addition, its full width at half maximum (FWHM) is also obviously widened. The method of enhancing fluorescence and energy transfer can widely be applied to photodetector, photocatalysis, optical display, optical sensing, and biomedical imaging, and so on.
关键词： porous Al2O3 film,colloidal self-assembled method,CdSe nano-wire,enhanced photoluminescence
更新于2025-11-25 10:30:42
-
Accidental contamination of substrates and polymer films by organic quantum emitters
摘要： We report the observation of ubiquitous contamination of dielectric substrates and polymethylmethacrylate matrices by organic molecules with optical activity in the visible spectral range. Contamination sites of individual solvent-related fluorophores in thin films of polymethylmethacrylate constitute fluorescence hotspots with quantum emission statistics and quantum yields approaching 30% at cryogenic temperatures. Our findings not only resolve prevalent puzzles in the assignment of spectral features to various nanoemitters on bare dielectric substrates or in polymer matrices, they also identify means for simple and cost-efficient realization of single-photon sources in the visible spectral range.
关键词： contamination of substrate and polymer matrix,organic fluorophores,single photon emitters,single molecule spectroscopy,Photoluminescence and fluorescence spectroscopy
更新于2025-11-25 10:30:42
-
Photoluminescence Intensity Enhancement of Single Silicon Quantum Dots on a Metal Membrane with a Spacer
摘要： Silicon quantum dots (Si QDs) featuring high photoluminescence (PL) intensity are necessary for the realization of different photonic and photovoltaic devices, such as light-emitting diodes (LEDs) and luminescent solar concentrators (LSCs). Herein, Si QDs on a (cid:1)100–200 nm thin silicon dioxide membrane with a metal back-coating are prepared. The dots are formed from the device layer of a silicon-on-insulator (SOI) wafer by etching and thermal oxidation. Aluminum is sputtered on the backside of the membrane, acting as a back-surface mirror, changing the local density of optical modes, as well as the local excitation ?eld. The PL properties of such Si QDs are then characterized at the single-particle level. It is found that the PL yield of single Si QDs on the membrane is enhanced by approximately one order of magnitude, compared with that of Si QDs outside the membrane under the same excitation power. These results indicate that advances in nanofabrication can substantially improve the optical properties of Si QDs, thus paving the way for their application.
关键词： membranes,quantum dots,silicon,blinking,photoluminescence
更新于2025-11-21 11:24:58
-
Fine Fabrication and Optical Waveguide Characteristics of Hexagonal tris(8-hydroxyquinoline)aluminum(a?￠) (Alq3) Crystal
摘要： Herein, we reported on the precise growth and optical waveguide characteristics of hexagonal tris(8-hydroxyquinoline)aluminum(III) (Alq3) micro-crystals (MCs). The hexagonal Alq3 MCs were prepared using surfactant-assisted assembly growth with the help of cetyltrimethylammoniumbromide (CTAB), in which the crystallization occurred as a result of molecular assembly and packing. Also, we adjusted the molar ratio of Alq3 and CTAB for the control degree of crystallization. The formation and structure of Alq3 MCs were investigated using field-emission scanning electron microscopy and X-ray diffraction pattern experiments, respectively. The solid-state laser confocal microscope-photoluminescence spectra and charge-coupled device images for the Alq3 MCs were measured to study the luminescence efficiency and colors, respectively. The optical waveguide performance of the hexagonal Alq3 MCs was measured for each side direction. According to our results, crystalline Alq3 micro-crystals are promising materials for application to the development of optical communication devices.
关键词： photoluminescence,crystallinity,organometal,surfactant,Alq3,confocal microscope,waveguide
更新于2025-11-21 11:24:58
-
Biocompatible photoluminescent silk fibers with stability and durability
摘要： Exploring photoluminescent silk fibers, possessing biocompatibility as well as stable and durable fluorescent properties, is a requirement for the development of novel photoluminescent biomaterials. Herein, we fabricate photoluminescent silk fibers, TPCA@SF, via modifying an organic fluorescent molecule (5-oxo-3,5-dihydro-2H-thiazolo [3,2-a] pyridine-7-carboxylic acid, TPCA) onto silk fibers, along with using quaternary ammonium salt didodecyldimethylammonium bromide (DDAB) as color fixing agent. The hydrogen bonds and electrostatic association among silk fibers, TPCA and DDAB ensure the stable modification. The facile and green fabrication process is achieved in water under mild conditions without using any toxic substances. The TPCA@SF manifests the combining features of high quantum yield, fluorescence water-fastness, anti-photobleaching, good mechanical property and biocompatibility. The strategy holds great potential for exploring various biocompatible photoluminescent substances with stability and durability.
关键词： wash-durability,biocompatibility,photoluminescence,silk fibers,anti-photobleaching
更新于2025-11-21 11:24:58
-
Structural characterization of tin nanocrystals embedded in silicon by atomic probe tomography
摘要： Tin nanocrystals embedded in silicon are studied by atom probe tomography and by photoluminescence spectroscopy in the 0.76–1.07 eV region of emission energies. The nanocrystals have been fabricated by molecular beam epitaxy followed by a post-growth annealing step at various temperatures. One particular sample, annealed at a temperature of 725 ?C, shows a distinctly higher optical activity. It is found, however, that the distinct behavior cannot be explained by variations in the nanocrystal composition or in the properties of Sn atoms dissolved in the surrounding Si matrix, which can be investigated by atom probe tomography.
关键词： Sn-nanocrystals,Photoluminescence,Atom probe tomography
更新于2025-11-21 11:20:42
-
Investigations of VO2+ doped SrZn2(PO4)2 nanophosphors by solution combustion synthesis
摘要： VO2+ doped SrZn2(PO4)2 nanophosphor is prepared using solution combustion synthesis. The prepared nanophosphor is studied by structural and spectral characterizations XRD, SEM with EDS, TEM, FT-IR, Optical absorption, EPR, and PL. XRD analyses the monoclinic phase of the prepared sample and the crystallite size determined to be in the order below 60 nm. SEM and TEM micrographs show the agglomerated stone-like structures for VO2+ doped SrZn2(PO4)2 nanophosphors. FT-IR spectrum exhibits various vibrational modes for PO4 3- anionic groups and other related groups. Optical absorption spectrum exhibited characteristic VO2+ bands in visible region and the crystal field and tetragonal field parameters are evaluated as Dq = 1461, Ds = -3035 and Dt = 602 cm-1. EPR spectrum shows well resolved hyperfine octet structure for VO2+ doped nanophosphor. The spin Hamiltonian parameters (g), hyperfine coupling constants (A) are calculated and are satisfying the condition g║<g┴<ge and A║ > A┴. From Optical and EPR data, VO2+ ions with the host ligands are identified as tetragonal distortion in octahedral site symmetry. PL spectrum illustrates, emission peaks in blue and green regions and its CIE and CCT parameters are evaluated, which are useful in LEDs and lightening devices.
关键词： Electron paramagnetic resonance,SrZn2(PO4)2 nanophosphor,Photoluminescence,tetragonal distortion,solution combustion
更新于2025-11-21 11:18:25
-
Structural, morphological, optical and electrical characterization of InGaN/GaN MQW structures for optoelectronic applications
摘要： InGaN/GaN Multiple Quantum Well (MQW) structures were grown on c-plane sapphire substrate using metal organic chemical vapour deposition technique by varying the MQW periods. The indium composition and thickness were estimated using high-resolution X-ray diffraction. InGaN well, GaN barriers and Indium composition were estimated as 3 nm, 18 nm and 16-18% using epitaxy smooth fit software. Reciprocal space mapping revealed that InGaN/GaN MQW samples were coherently strained. High-resolution transmission electron microscopy and scanning electron microscopy exhibit decrease in the surface roughness with increase in the number of InGaN/GaN MQW periods with respect to the number of defects comprising of threading dislocations and hexagonal V-pits. Self-organized In(Ga)N like nanostructures with spiral growth mechanism was also observed due to the low temperature growth of p-GaN layer. The photoluminescence spectra of the MQWs showed a red-shift when the number of QW periods was increased due to quantum confined stark effect. Hall Effect microscopy images confirmed good interface between the InGaN/GaN MQW structures. Atomic force microscopy and scanning electron microscopy exhibit decrease in the surface roughness measurement displayed good semiconducting behavior in the InGaN/GaN MQW structures. The carrier concentration values also emphasized adequate variations when number of periods was increased.
关键词： V-pits,InGaN,Photoluminescence,Multiple Quantum Well,nanostructures
更新于2025-11-21 11:18:25
-
Microwave-assisted oleothermal synthesis of graphene-TiO2 quantum dots for photoelectrochemical oxygen evolution reaction
摘要： In this work, it was reported the production of graphene-TiO2-quantum dots based on an oleothermal redox reaction. Using concepts of nanoemulsification, an oil-water stable nanodroplets were formed. This emulsion was treated at different temperatures in an oil-based medium. This is an advantage to obtain well dispersed hydrophilic nanoparticles, considering that using water as solvent promotes their agglomeration. The cluster of hydrate titanium is formed inside the water dispersed graphene oxide nanodroplet in the oil medium. This aspect assures a close connection between graphene layers and titanium ions, originating dispersed quantum dots of minimum size. Temperature and time of oleothermal reaction influence the degree of functionalization of the graphene layers and thus the photoluminescence characteristics. For the water splitting characterization, a transparent thin film was obtained using the electrophoresis. It was possible to correlate the degree of oxygen functionalization of the graphene layers with the oleothermal conditions and the generated photocurrents.
关键词： Oleothermal,Quantum dots,Photoluminescence,Graphene,Photocurrent
更新于2025-11-21 11:18:25