Photoluminescence Of ZnS Research Articles

Photoluminescence enhancement and quenching of ZnS:Mn2+ in the presence of Au and Ag nanoparticles synthesized by pulse laser ablation in solution.

Abstract: Gold (Au) and silver (Ag) nanoparticles were synthesized by laser ablation in water. The average sizes of Au and Ag nanoparticles are 18,4 nm and 21,8 nm respectively. ZnS:Mn2+ nanoparticles with average size of 3-5 nm were prepared by a co-precipitation method. The photoluminescence of ZnS:Mn2+solution in mixture with Au (Ag) nanoparticle colloids was investigated. The quenching effect on Mn2+ emission at 601 nm band were observed in the presence of the Au and Ag nanoparticles while the D-A emission at 445 nm band was enhanced and blue shifted by Au nanoparticles . The results and discussion are presented in this report.

Formation and photoluminescence of ZnS:Tb nanoparticles stabilized by polyethylene glycol

Abstract ZnS nanoparticles doped with 1 mol.% of Tb have been prepared at 70 °C by simple chemical precipitation method using poly ethylene glycol (PEG) as capping agent. The synthesized nanoparticles have been analysed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), photoluminescence (PL) and UV–Vis absorption spectroscopy. From X-ray diffraction analysis, it was found that nanostructured ZnS:Tb particles exhibited cubic structure with an average crystallite size of 2.75 nm. Room temperature photoluminescence (PL) spectrum of the doped sample exhibited broad emission in the visible region with multiple peaks at 395 and 412 nm due to 5D3 →7F6 and 7F5 transitions and 492, 536, 600, 653 and 680 nm due to 5D4 →7F6, 7F5 ,7F4,7F1and 7F0 transitions.

Luminescent modulation of zinc sulphide nano-particles by thermal injection method

ZnS coating with oleic acid nano-particles have been successfully synthesized through the oil-phase thermal injection method. As-prepared samples are characterized by powder X-ray diffraction, transmission electron microscopy and spectra analysis. The emission color of ZnS NPs changes from blue to cyan with different ratio of Zn/S. ZnS:xEu3+ NPs with different doping concentrations of Eu3+ ions have different emission intensities and CIE coordination. The emission peaks vary with the change of y value of ZnSeyS1-y NPs, and the chromaticity coordinate transit from green to yellow region. The emission color and mechanism of the luminescent properties of ZnS, ZnS:xEu3+ and ZnSeyS1-y NPs are studied in detail. The results indicate that the thermal mixture injection without toxic is an effective and green method for synthesizing metal sulphitde, and the energy level structure, particle size, photoluminescence of ZnS can be achieved by forming different defect or doping of Eu or Se ions.

The influence of Mn content on the structure and photoluminescence of ZnS:Mn nanostructure

ZnS:Mn nanostructure was grown on Si substrates by hydrothermal method. The effects of Mn doping concentration on the structure and luminescence properties of ZnS:Mn were studied in detail. XRD patterns show that all the samples have a strong diffraction peak at about 28.5°, which belongs to β-ZnS (111) orientation. As the concentration of Mn increases, the diffraction peak shifts to a small angle, and the average grain size decreased. SEM images show that ZnS:Mn nanostructure is spherical particle, and these particles are closely bonded to the substrate. PL spectra of all samples are composed of two luminescence bands: green light around 500nm and orange-yellow light around 580nm. When the doping concentration of Mn increased from 0.5% to 2%, the 4T1-6A1 emission of Mn2+ around 580nm gradually increased, and when the concentration exceeded 2%, the luminous intensity decreased instead.

One-pot synthesis of color-tunable copper doped zinc sulfide quantum dots for solid-state lighting devices

Color-tunable semiconductor quantum dots (QDs) are highly attractive for a wide range of applications including imaging, sensing, and lighting. Herein, we reported a facile synthesis of copper-doped zinc sulfide quantum dots (ZnS:Cu QDs) with tunable emission colors, using a microwave-assisted one-pot reaction. 3-mercaptopropionic acid (MPA) was used as a stabilizer agent and sulfide source for the formation of ZnS:Cu QDs. The photoluminescence of ZnS:Cu QDs showed a clear red-shift as increasing Cu concentration, which can be controlled by microwave irradiation time. As increasing the irradiation time, the emission color (peak) of ZnS:Cu QDs changed from blue (500 nm) to green (540 nm), yellow (580 nm), and to orange-red (595 nm). The obtained ZnS:Cu QDs were highly luminescent, as evidenced by their high quantum yields. The potential utility of ZnS:Cu QDs as a novel lighting source was demonstrated in a near-UV chip-based white light-emitting diode.

Photoluminescence of ZnS:Cu in a Polymethyl Methacrylate Matrix

The method of agents arising directly in the (poly)methyl methacrylate medium is used to synthesize ZnS:Cu quantum dots fixed in an optically transparent polymer matrix. The optical transmittance of the polymer composites in the visible spectral region reaches 92% (at the thickness 5 mm). The photoluminescence of the (poly)methyl methacrylate/ZnS:Cu composite is defined by defects in the crystal structure of ZnS and by the system of energy levels in the band gap of ZnS. The photoluminescence signal depends on the Cu-ion concentration, the reabsorption of radiation in ZnS and (poly)methyl methacrylate, and other factors.

Application of derivative spectroscopy method to photoluminescence in ZnS:Mn nanocrystals

Application of derivative spectroscopy method to photoluminescence in ZnS:Mn nanocrystals

Photoluminescence of ZnS: Mn quantum dot by hydrothermal method

ZnS: Mn quantum dots (QDs) with the average grain size from 4.2 to 7.2 nm were synthesized by a hydrothermal method. All samples were cubic zinc blende structure (β-ZnS) measured using X-ray diffraction (XRD). And the main diffraction peaks of ZnS: Mn shifted slightly towards higher angle in comparison with the intrinsic ZnS because of the substitution of Mn2+ for Zn2+. Due to the small grain size (4-7 nm) effect, the poor dispersion and serious reunion phenomenon for the samples were observed from transmission electron microscopy (TEM). ZnS: Mn QDs had four peaks centered at 466, 495, 522, and 554 nm, respectively, in the photoluminescence (PL) spectra, in which the band at 554 nm absent in the intrinsic ZnS: Mn is attributed to the doping of Mn2+ in the lattice sites. As the concentration of Mn2+ increasing from 0% to 0.6 at%, the intensity of the PL emission also increased. But the concentration reached 0.9 at%, quenching of PL emission occurred. The peak in ZnS: Mn QDs observed at 490 cm-1 was originated from the stretching vibration of the Mn–O bonds in the Fourier transform infrared (FTIR) spectra. And the small changes about this peak compared with the previous reports at 500 cm-1 can be attributed to the formation of quantum dots. This method we utilized to synthesize ZnS: Mn QDs is very simple, low cost, and applicable for other semiconductor QD materials.

Hysteresis compensation of photoluminescence in ZnS:Cu for noncontact shaft torque sensing.

This paper presents a preliminary investigation of loading rate-dependent hysteresis of photoluminescence (PL) by phosphorescence quenching of copper-doped zinc sulfide (ZnS:Cu) microparticles in response to dynamic torsional loading. Precision sinusoidal torque waveforms in the frequency range of 0.5-3 Hz are used to identify the loading rate-dependent (i.e., frequency-dependent) nonlinear hysteresis phenomenon. The potential of the application of PL is demonstrated by successfully measuring the sinusoidal torque applied to a rotational shaft by evaluating the loading rate-dependent PL intensity signature using a photomultiplier tube. In addition, the potential of noncontact shaft torque sensing is demonstrated successfully by the simple compensation derived from ad hoc heuristic characterization.

A general and rapid synthesis of metal sulphides hollow spheres that have properties enhanced by salt-assisted aerosol decomposition: a case of ZnS and other multicomponent solid solutions

Synthesis of hollow structures of metal sulphides generally involves various templates and complex chemical processing. In the present study, a general and rapid method of salt-assisted aerosol decomposition (SAD) is presented for the synthesis of hollow spheres of various metal sulfides, including ZnS, ternary sulfides, and solid solutions. The NaCl salt plays a critical role in the formation of hollow spheres of metal sulfides. The hollow spherical microstructure was formed from solid by using a small amount of water soluble NaCl salt. The formation of metal sulphide hollow spheres differs from previous mechanisms and is referred to as molten salt heterogeneous nucleation (MSHN). The present method offers the most promising advantage for controlling the multicomponent composition of hollow spheres. Furthermore, hollow spheres of sulphides have much enhanced properties such as photoluminescence of ZnS:Mn2+ and photocatalytic dye degradation of ZnIn2S4 due to the role of molten salt in the promotion of crystallization, The present method could be explored further by applying the process to other compounds such as sulfides, oxides, and nitrides.

Experimental and Theoretical Studies of Photoluminescence in ZnS Obtained by Microwave-Assisted Solvothermal Method

A shift of the photoluminescence (PL) emission was observed in ZnS prepared by microwave assisted solvothermal method with the increase of the time in microwave. In this work we reported a study of the optical behavior linking with the structural disorder according to XRD and FEG-TEM results. The reduction of intrinsic defects in the lattice is responsible for the decrease of electronic levels in the band gap changing the PL profile. This effect was confirmed by electronic structure calculations. Keywords: Semiconductor, Zinc compounds, Optical properties, Density functional theory, Ab initio calculations, Structural disorder, nanoparticle, visible spectra, deformation, photoluminescence.

Highly porous ZnS microspheres for superior photoactivity after Au and Pt deposition and thermal treatment

This work highlights the enhanced photocatalytic activity of porous ZnS microspheres after Au and Pt deposition and heat treatment at 500°C for 2h. Microporous ZnS particles of size 2–5μm with large surface area 173.14m2g−1 and pore volume 0.0212cm3g−1 were prepared by refluxing under an alkaline medium. Photoluminescence of ZnS at 437nm attributed to sulfur or zinc vacancies were quenched to 30% and 49%, respectively, after 1wt% Au and Pt loading. SEM images revealed that each ZnS microparticle consist of several smaller ZnS spheres of size 2.13nm as calculated by Scherrer's equation. The rate of photooxidation of 4-nitrophenol (10μM) under UV (125WHg arc–10.4mW/cm2) irradiation has been significantly improved by Au and Pt deposition followed by sintering due to better electron capturing capacity of deposited metals and growth of crystalline ZnS phase with less surface defects.

Synthesis and photoluminescence properties of Cl−-doped ZnS nanoparticles prepared by a solid-state reaction

ZnS:Cl− nanoparticles with strong blue emission have been synthesized successfully by a solid-state reaction at low temperature. The dependence of photoluminescence (PL) properties of ZnS:Cl− nanoparticles on the Cl− contents was researched, and the influences of the annealing ambience and using polyvinyl alcohol (PVA) during the synthesis on the PL of ZnS:Cl− (Cl/Zn = 0.35) nanoparticles were discussed. X-ray power diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and ultraviolet-visible spectroscopy were used to characterize their structure, chemical state, diameter, surface states, and PL properties. The results showed that ZnS:Cl− nanoparticles had a cubic blende crystal structure and an average crystallite size of 17.40–19.16 nm. The most intensity blue emission peaking at about 425 nm was obtained when Cl/Zn = 0.35 under 330 nm excitation at room temperature. The emission intensity of ZnS:Cl− (Cl/Zn = 0.35) was increased 3-fold than that of ZnS. The results showed that the PL of ZnS:Cl− (Cl/Zn = 0.35) nanoparticles was enhanced after annealing or using PVA during the synthesis, and annealing in vacuum had a stronger effect in improving the luminescence properties of ZnS nanoparticles than in air. This work suggests that it is an effective method to improve the PL intensity of ZnS nanocrystals by doping with Cl− in ZnS.

Photoluminescence of ZnS–SiO2:Ce Thin Films Deposited by Magnetron Sputtering

Photoluminescence of ZnS–SiO₂:Ce Thin Films Deposited by Magnetron Sputtering

Luminescent Characteristics of Bi Co-doped ZnS:Mn Yellow Phosphors for White Light Emitting Diodes

Bi co-doped ZnS:Mn,Bi yellow phosphors for white light emitting diodes were prepared by the conventional solidstate reaction method. The optical and structural properties of ZnS:Mn,Bi phosphors were investigated by x-ray diffraction, scanning electro microscopy and photoluminescence. ZnS:Mn,Bi phosphors showed XRD patterns of hexagonal structure. The photoluminescence of ZnS:Mn,Bi phosphors showed spectra extending from 480 to 700 nm, peaking at 580 nm. The photoluminescence of 580 nm in the ZnS:Mn,Bi phosphors was associated with the 4T1 <TEX>${\rightarrow}$</TEX> 6A1 transition of the Mn2+ ions. The highest photoluminescent intensity of the phosphors under 405 nm and 450 nm excitation was obtained at Bi concentration of 7mol%. The optimum mixing conditions with epoxy and yellow phosphor for white light emitting diodes were observed in a ratio of epoxy:yellow phosphor of 1:3.5. The CIE chromaticity of the white LED at the 1:3.5 ratio was X = 0.3454 and Y = 0.2449.

Corrigendum to “Combustion synthesis and photoluminescence of ZnS:Mn+2 particles” [Journal of Luminescence 130 (2010) 1026–1031

Corrigendum to “Combustion synthesis and photoluminescence of ZnS:Mn+2 particles” [Journal of Luminescence 130 (2010) 1026–1031

Combustion synthesis and photoluminescence of ZnS:Mn +2 particles

An efficient process based on a solid-state combustion technique has been developed to produce high crystalline and micrometer sized particles of ZnS:Mn +2 phosphor with sphalerite structure. The precursor mixture of 0.915Zn+S+0.05Mn+0.035ZnCl 2+ kNaCl composition (where k is the mole number of NaCl) was combusted under the argon atmosphere followed by post-heat treatment procedure at 700 °C. It was shown that photoluminescence (PL) intensity of ZnS sample can be easily controlled through adjusting NaCl concentration. In the optimized reaction conditions ZnS samples have showed PL intensity almost comparable to that of a commercial one, despite the relatively low purity of precursor materials used. Many interesting phenomena such as high luminescent efficiency, pure cubic ZnS formation after the post-heat treatment and strong influence of Cl − ion on PL intensity have been observed and discussed.

Effect of Precursor Molar Ratio of [S2−]/[Zn2+] onParticle Size and Photoluminescence of ZnS:Mn2+ Nanocrystals

We investigate the influence of precursor molar ratio of[S2−]/[Zn2+] on particle size and photoluminescence (PL)of ZnS:Mn2+ nanocrystals. By changing the[S2−]/[Zn2+] ratio from 0.6 (Zn-rich) to 2.0 (S-rich),the particle size increases from nearly 2.7 nm to about 4.0 nm. Theincrease in the ratio of [S2−]/[Zn2+] causes a decreaseof PL emission intensity of ZnS host while a distinct increase ofMn2+ emission. The maximum intensity for the luminescence ofMn2+ emission is observed at the ratio of[S2−]/[Zn2+]≈1.5. The possible mechanism for the resultsis discussed by filling of S2− vacancies and the increase ofMn2+ ions incorporated into ZnS lattices.

Photoluminescence of ZnS:Tb phosphors fritted with different fluxes

ZnS:Tb phosphor powders were prepared by solid-state synthesis. Without addition of flux, only emission from the host luminescence was observed. There is no the characteristic luminescence of Tb for ZnS:Tb without the additions of fluoride fluxes or chloride fluxes. For ZnS:Tb with LiF, NaF and KF additions, characteristic luminescence of Tb emerges, which corresponds to the transitions of 5D 4 → 7F J. The highest peak is located at 548 nm. For ZnS:Tb with additions of NaCl and KCl fluxes, both the characteristic luminescence of Tb and the luminescence of the host material were observed. However, only the host luminescence was shown in the spectrum for ZnS:Tb fritted with LiCl. It is difficult to observe the characteristic luminescence of Tb. The microstructure of ZnS:Tb fritted with chlorine fluxes show well crystallized uniform grains. However, with fluoride fluxes, huge crystalline grains with irregular morphology were obtained.

Synthesis and photoluminescence of ZnS:Cu nanoparticles

The room-temperature photoluminescence (PL) of copper doped zinc sulfide (ZnS:Cu) nanoparticles were investigated. These ZnS:Cu nanoparticles were synthesized by a facile wet chemical method, with the copper concentration varying from 0 to 2 mol%. By Gaussian fitting, the PL spectrum of the undoped ZnS nanoparticles was deconvoluted into two blue luminescence peaks (centered at 411 nm and 455 nm, respectively), which both can be attributed to the recombination of the defect sates of ZnS. But for the doped samples, a third peak at about 500 nm was also identified. This green luminescence originates from the recombination between the shallow donor level (sulfur vacancy) and the t(2) level of Cu2+. With the increase of the CU2+ concentration, the green emission peak is systematically shifted to longer wavelength. In addition, it was found that the overall photoluminescence intensity is decreased at the Cu2+ concentration of 2%. The concentration quenching of the luminescence may be caused by the formation of CuS compound. (c) 2005 Elsevier B.V. All rights reserved.