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Red-emitting CsPbI3 perovskite materials are still limited in various commercial applications because of their stability being related to the morphology and dimension. In this paper, a solvothermal method was developed to fabricate CsPbI3 perovskite nanomaterials with governable morphologies (e.g., nanoplatelets (NPLs) to nanocubes (NCs)) and dimensions ranging from the zero-dimensional (0D) Cs4PbI6 to the three-dimensional (3D) CsPbI3. By adjusting the amount of Cs precursor solutions, the photoluminescence (PL) peak position of the samples was tuned over the whole red-emitting region (from 607 to 700 nm). In addition, the reaction temperature affected the PL properties of the samples and demonstrated that temperature was critical to control the performance of CsPbI3 perovskite materials. Furthermore, sodium dodecyl benzene sulfonate (SDBS) was chosen as the additive to improve the stability of the prepared samples. The result provided an approach to get CsPbI3 perovskite nanocrystals with stabile PL. Finally, CsPbI3 NPLs embedded in the polystyrene film displayed bright and stable white light emission. [ABSTRACT FROM AUTHOR]

CdTe0.5Se0.5/Cd0.5Zn0.5S core/shell quantum dots (QDs) with a tunable photoluminescence (PL) range from yellow to dark red (up to a PL peak wavelength of 683 nm) were fabricated using various reaction systems. The core/shell QDs created in the reaction solution of trioctylamine (TOA) and oleic acid (OA) at 300 °C exhibited narrow PL spectra and a related low PL efficiency (38%). In contrast, the core/shell QDs prepared in the solution of 1-octadecene (ODE) and hexadecylamine (HDA) at 200 °C revealed a high PL efficiency (70%) and broad PL spectra. This phenomenon is ascribed that the precursor of Cd, reaction temperature, solvents, and ligands affected the formation process of the shell. The slow growth rate of the shell in the solution of ODE and HDA made QDs with a high PL efficiency. Metal acetate salts without reaction with HDA led to the core/shell QDs with a broad size distribution. [ABSTRACT FROM AUTHOR]

The synthesis and photoluminescence (PL) properties of aqueous CdTe/ZnO core/shell quantum dots (QDs) have been investigated by using thiolglycolic acid as a capping reagent. The highlighted contribution of the present study was CdTe QDs coated with a ZnO shell by controlling the hydrolysis process of Zn(OAc). The QDs benefitted from overcoming the high lattice mismatch between CdTe and ZnO. The PL peak wavelength of the CdTe/ZnO QDs with high PL quantum yields up to 88% was located in a range between 547 and 596 nm by adjusting the size of CdTe cores and the thickness of ZnO shells. The results of X-ray diffraction analysis and transmission electron microscopy observation indicate that the dot-shaped CdTe/ZnO QDs (566 nm) with an average size of 2.2 nm in diameter belong to the cubic CdTe crystal structure. Due to the passivation of surface defects, it is found that the luminescence decay curves accord with a biexponential decay model of exciton and trap radiation behavior. The average PL lifetimes of CdTe (571 nm) and CdTe/ZnO (596 nm) QDs at room temperature are 27.3 and 35.1 ns, respectively. [ABSTRACT FROM AUTHOR]

Abstract: Hydrophobic oleic acid-capped CdSe/Cd x Zn1−x S core/shell quantum dots (QDs) with high photoluminescence (PL) efficiency of 62% and a PL peak wavelength of 602nm were assembled in SiO2 particles through a novel silanization technique. Ligand exchange (3-mercaptopropyltrimethoxysilane (MPS) instead of oleic acid) occurred via the connection of mercapto groups and QDs when MPS was added in the toluene solution of the QDs. After being silanized using MPS, partially hydrolyzed tetraethyl orthosilicate (TEOS) was attached to the surface of the silanized QDs. The hydrophobic CdSe/Cd x Zn1−x S QDs were then transferred from toluene phase to water phase by the hydrolysis of TEOS through the addition of ethanol, ammonia, and water. Further hydrolysis and condensation of the TEOS and MPS causes them to form assemblies in the water phase. MPS is crucial for proper assembly of the QDs in SiO2 particles and for controlling the size of resulting SiO2 particles. The resulting SiO2 particles exhibited tunable diameters from several tens to 100nm. After being encapsulated in SiO2 particles, the QDs revealed a PL efficiency of 25%. Because of the resulting SiO2 particles encapsulating multiple hydrophobic CdSe/Cd x Zn1−x S QDs and having a functional surface (mercapto group), they are applicable to bio-probes. [Copyright &y& Elsevier]

Abstract: A facile and energy saving sol–gel combustion method has been used to prepare La2Zr2O7 nanocrystallines. The pyrochlore La2Zr2O7 nanocrystals have been obtained at a relatively low temperature with the grain size ranging from 45 to 70nm. Eu3+ and Dy3+ have been introduced into the La2Zr2O7 crystal structure, respectively, and the intense photoluminescence was observed. The relative intensity of electric dipole transition and magnetic dipole transition is considered for luminescence emission both of Eu3+ and Dy3+. The dependence of luminescence intensity on dopant concentration and the effect of Dy3+ co-doping on Eu3+ luminescence are also discussed. [Copyright &y& Elsevier]

Abstract: Strontium zirconate (SrZrO3) nanocrystals with an average size of 19nm were prepared by a simple sol–gel combustion method. The combustion reaction was induced just at 300°C. Under conventional UV excitation, the SrZrO3 nanocrystals showed a strong violet emission at 400nm. The number of luminescent zirconates is small, especially of those with visible emission. The novel luminescence was tentatively attributed to the existence of defect levels. Further study was carried out corresponding the size dependence of the luminescence property. [Copyright &y& Elsevier]

Abstract: CdTe nanocrystals (NCs) were coated with a hybrid SiO2 shell containing CdS-like clusters by a facile reflux. These hybrid SiO2-coated CdTe NCs exhibited tunable photoluminescence (PL) and high fluorescence quantum yields (QYs) up to 70% (the QY of initial CdTe NCs is 24%) due to the CdS-like cluster in the SiO2 shell nearby the CdTe core. The average fluorescence lifetime of the hybrid SiO2-coated NCs and the CdTe NCs are 36 and 25ns, respectively. Because increased fluorescence QYs and slightly blue-shifted PL peak wavelength for these hybrid NCs were observed after the removing of TGA and Cd2+, the hybrid SiO2 shell can sufficiently passivate PL, improve chemical stability, and prevent the surface deterioration of the CdTe NCs. This is crucial for applications in biolabeling and optoelectronic devices. [Copyright &y& Elsevier]

Abstract: Highly luminescent euxenite phased YNbTiO6:Eu3+ and Li+-doped YNbTiO6:Eu3+ red phosphors have been prepared through a facile sol–gel combustion process and investigated for the first time. The introduction of Li+ ions into YNbTiO6:Eu3+ is able to result in significant changes of the crystallinity and particle size, and bring a clear red-shift of absorption edge. A dominant red emission peak at 611nm due to the 5D0 → 7F2 transition of Eu3+ was observed from photoluminescence spectra of the YNbTiO6:Eu3+ and Li+-doped YNbTiO6:Eu3+ phosphors. In particular, the emission intensity of the optimal Li+-doped YNbTiO6:Eu3+ was examined to be close to 400% of commercial Y2O3:Eu3+ phosphor. The mechanism of the enhanced emission by Li+ doping was discussed. [Copyright &y& Elsevier]

Highlights: [•] YNbTiO6-based phosphors were synthesized by a sol–gel combustion method. [•] The annealing temperature plays the key role of PL properties and particle size. [•] Luminescence of Mn2+, Er3+, and Dy3+-doped YNbTiO6 host was achieved. [•] Luminescent mechanism of Er3+ or Dy3+-doped samples is dipole–dipole interaction. [•] Mn2+ →Er3+ (Dy3+) energy transfers were observed for co-doped phosphors. [Copyright &y& Elsevier]

Abstract: Undoped and Eu3+-activated Bi3TiNbO9 (BTNO) nanophosphors have been successfully synthesized by sol–gel combustion method. The effects of thermal annealing on the phase structure and crystallinity, morphology and UV–vis absorption of BTNO particles were investigated. Photoluminescence (PL) properties show that a broad blue emission was detected for BTNO nanoparticles, and the characteristic Eu3+ ion 5D0 → 7F J (J =1, 2, 3, 4) transitions were observed for the doped samples. Further investigation illuminates that the Eu3+ ions substituted for Bi3+ ions at A site in the pseudo-perovskite layers. It can be confirmed from high bright fluorescence image and short decay time that the novel orange-red phosphor has the potential applications in luminescence devices. [Copyright &y& Elsevier]

Abstract: Nb2O5 nanorods have been prepared using water/ethanol media. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV–visible absorption and photoluminescence spectroscopy. The as-prepared Nb2O5 nanorods appeared to be single pseudohexagonal (TT-Nb2O5) phase. From the photoluminescence spectrum, two emission bands at 407 and 496nm, respectively, were observed. The origin of the luminescence was discussed in detail. [Copyright &y& Elsevier]

Abstract: Pure and Mn-doped SrNb2O6 nanoparticles have been prepared by sol–gel combustion method using citric acid as fuel and complexing agent and nitrates as oxidants at a relatively low temperature compared to solid-state reaction method. X-ray diffraction (XRD) patterns of the pure SrNb2O6 samples show that the SrNb2O6 nanoparticles exhibited orthorhombic phase. Photoluminescence (PL) properties of all the undoped and Mn-doped samples were studied in detail. For the pure SrNb2O6 samples, a strong blue emission band centered at 442nm and two weak emission bands centered at 524nm and 626nm, respectively, can be observed. For the Mn-doped SrNb2O6 samples, no emission from Mn2+ was observed while the blue emission intensity of SrNb2O6 varied with the Mn-doping concentration. This novel PL characteristic of the doped samples was explained. [Copyright &y& Elsevier]

Abstract: A new red emitting phosphor, Ca3(VO4)2:Eu3+; Mn2+, was synthesized by a citric acid sol–gel combustion method and characterized by XRD, TEM and photoluminescence (PL) spectra. The red emission located at about 613nm was ascribed to 5D0–7F2 transition of Eu3+. And the red luminescence intensity changed with annealing temperature and concentration of Eu3+. The effect of the co-doped Mn2+ was also investigated systematically. [Copyright &y& Elsevier]

Abstract: Pure and Dy3+-doped Zn2SnO4 (ZTO) hollow spheres, integrated with nanoparticles, have been synthesized using the coprecipitation method. The ZTO spheres have been characterized with X-ray diffraction and scanning electron microscope. The photoluminescence and photocatalytic properties are investigated. The influences of Dy3+ ions on the morphology and the photoluminescence of ZTO have been explained in detail. [Copyright &y& Elsevier]