Synthesis, characterization, photophysics and electrophosphorescent applications of phosphorescent platinum cyclometalated complexes with 9-arylcarbazole moieties

A series of cyclometalating platinum(II) complexes with substituted 9-arylcarbazolyl chromophores have been synthesized and characterized. These complexes are thermally stable and most of them have been characterized by X-ray crystallography. The phosphorescence emissions of the complexes are dominated by (MLCT)-M-3 excited states. The excited state properties of these complexes can be modulated by varying the electronic characteristics of the cyclometalating ligands via substituent effects, thus allowing the emission to be tuned from bright green to yellow, orange and red light. The correlation between the functional properties of these metallophosphors and the results of density functional theory calculations was made. Because of the propensity of the electron-rich carbazolyl group to facilitate hole injection/transport, the presence of such moiety can increase the highest occupied molecular orbital levels and improve the charge balance in the resulting complexes relative to the parent platinum(II) phosphor with 2-phenylpyridine ligand.

Synthesis and characterization of monodisperse spherical SiO2@RE2O3 (RE = rare earth elements) and SiO2@Gd2O3:Ln(3+) (Ln = Eu, Tb, Dy, Sm, Er, Ho) particles with core-shell structure

Spherical SiO2 particles have been coated with rare earth oxide layers by a Pechini sol-gel process, leading to the formation of core-shell structured SiO2@RE2O3 (RE = rare earth elements) and SiO2@Gd2O3:Ln(3+) (Ln = Eu, Tb, Dy, Sm, Er, Ho) particles. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), photoluminescence (PL), and cathodoluminescence spectra as well as lifetimes were used to characterize the resulting SiO2@RE2O3 (RE = rare earth elements) and SiO2@Gd2O3:Ln(3+) (Eu3+, Tb3+, Dy3+, Sm3+, Er3+, Ho3+) samples. The obtained core-shell phosphors have perfect spherical shape with narrow size distribution (average size ca. 380 nm), smooth surface and non-agglomeration. The thickness of shells could be easily controlled by changing the number of deposition cycles (40 nm for two deposition cycles).

Reduction of Eu3+ to Eu2+ in MAl2Si2O8 (M = Ca, Sr, Ba) in air condition

In general, the reduction of Eu3+ to Eu2+ in solids needs an annealing Process in a reducing atmosphere. in this paper, it is of great interest and importance to find that the reduction of Eu3+ to Eu2+ can be realized in a series of alkaline-earth metal aluminum silicates MAl2Si2O8 (M = Ca, Sr, Ba) just in air condition. The Eu2+-doped MAl2Si2O8 (M = Ca, Sr, Ba) powder samples were prepared in air atmosphere by Pechini-type sol-gel process. It was found that the strong hand emissions of 4f(6)5d(1)-4f(7) from Eu2+ were observed at 417, 404 and 373 nm in air-annealed CaAl2Si2O8, SrAl2Si2O8 and BaAl2Si2O8, respectively, under ultraviolet excitation although the Eu3+ precursors were employed. In addition, under low-voltage electron beam excitation, Eu2+-doped MAl2Si2O8 also shows strong blue or ultraviolet emission corresponding to 4f(6)5d(1)-4f(7) transition.

Preparation and luminescence properties of Ce3+ and/or Tb3+ doped LaPO4 nanofibers and microbelts by electrospinning

Ce3+ and/or Tb3+ doped LaPO4 nanofibers and microbelts have been prepared by a combination method of sol-gel process and electrospinning. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), photoluminescence (PL), low voltage cathodoluminescence (CL) and time-resolved emission spectra as well as kinetic decays were used to characterize the resulting samples. SEM and TEM results indicate the as-formed precursor fibers and belts are smooth. and the as-prepared nanofibers and microbelts consist of nanoparticles. The doped rare-earth ions show their characteristic emission under ultraviolet excitation, i.e. Ce3+ 5d-4f and Tb3+ D-5(4)-F-7(j) (J = 6-3) transitions, respectively. The energy transfer process from Ce3+ to Tb3+ in LaPO4:Ce3+, Tb3+ nanofibers was further studied by the time-resolved emission spectra.

Facile sonochemical synthesis and photoluminescent properties of lanthanide orthophosphate nanoparticles

Uniform lanthanide orthophosphate LnPO(4) (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho) nanoparticles have been systematically synthesized via a facile, fast, efficient ultrasonic irradiation of inorganic salt aqueous solution under ambient conditions without any surfactant or template. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), photoluminescence (PL) spectra as well as kinetic decays were employed to characterize the samples. The SEM and the TEM images show that the hexagonal structured lanthanide orthophosphate LnPO(4) (Ln = La, Ce, Pr, Nd. Sm, Eu, Gd) products have nanorod bundles morphology, while the tetragonal LnPO(4) (Ln = Tb, Dy, Ho) samples prepared under the same experimental conditions are composed of nanoparticles. HRTEM micrographs and SAED results prove that these nanostructures are polycrystalline in nature.

Preparation and luminescence properties of Mn2+-doped ZnGa2O4 nanofibers via electrospinning process

One-dimensional Mn2+-doped ZnGa2O4 nanofibers were prepared by a simple and cost-effective electrospinning process. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric and differential thermal analysis (TG-DTA), scanning electron microscopy (SEM), energy-dispersive X-ray spectrum (EDS), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), photoluminescence (PL) and cathodoluminescence (CL) spectra as well as kinetic decays were used to characterize the samples. SEM results indicated that the as-formed precursor fibers and those annealed at 700 degrees C are uniform with length of several tens to hundred micrometers, and the diameters of the fibers decrease greatly after being heated at 700 degrees C. Under ultraviolet excitation (246 nm) and low-voltage electron beams (1-3 kV) excitation, the ZnGa2O4:Mn2+ nanofibers presents the blue emission band of the ZnGa2O4 host lattice and the strong green emission with a peak at 505 nm corresponding to the T-4(1)-(6)A(1) transition of Mn2+ ion.

Hydrothermal synthesis and luminescent properties of Y2O3:Tb3+ and Gd2O3:Tb3+ microrods

One-dimensional (1D) Y2O3:Tb3+ and Gd2O3:Tb3+ microrods have been successfully prepared through a large-scale and facile hydrothermal method followed by a subsequent calcination process in N-2/H-2 mixed atmosphere. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (IR), thermogravimetric analysis (TGA), energy-dispersive X-ray spectra (EDX). scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), photoluminescence (PL) and cathodoluminescence (CL) spectra as well as kinetic decays were used to characterize the samples. The as-formed products via the hydrothermal process could transform to cubic Y2O3:Tb3+ and Gd2O3:Tb3+ with the same morphology and slight shrinking in size after a postannealing process.

Self-assembled 3D flowerlike Lu2O3 and Lu2O3 : Ln(3+) (Ln = Eu, Tb, Dy, Pr, Sm, Er, Ho, Tm) microarchitectures: Ethylene glycol-mediated hydrothermal synthesis and luminescent properties

Three-dimensional flowerlike Lu2O3 and Lu2O3:Ln(3+) (Ln = Eu, Th, Dy, Pr, Sm, Er, Ho, Tm) microarchitectures have been successfully synthesized via ethylene glycol (EG)-mediated hydrothermal method followed by a subsequent heat treatment process. X-ray diffraction, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectra, thermogravimetric and differential thermal analysis, elemental analysis, inductively coupled plasma atomic absorption spectrometric analysis, ion chromatogram analysis, X-ray photoelectron spectra, scanning electron microscopy, transmission electron microscopy, photoluminescence spectra as well kinetic decays, and cathodoluminescence spectra were used to characterize the samples. Hydrothermal temperature, EG, and CH3COONa play critical roles in the formation of the lutetium oxide precursor microflowers. The reaction mechanism and the self-assembly evolution process have been proposed. The as-formed lutetium oxide precursor could transform to Lu2O3 With their original flowerlike morphology and slight shrinkage in the size after postannealing process.

Multiform oxide optical materials via the versatile Pechini-type sol-gel process: Synthesis and characteristics

This feature article highlights work from the authors' laboratories on the various kinds of oxide optical materials, mainly luminescence and pigment materials with different forms (powder, core-shell structures, thin film and patterning) prepared by the Pechini-type sol-gel (PSG) process. The PSG process, which uses the common metal salts (nitrates, acetates, chlorides, etc.) as precursors and citric acid (CA) as chelating ligands of metal ions and polyhydroxy alcohol (such as ethylene glycol or poly ethylene glycol) as a cross-linking agent to form a polymeric resin on molecular level, reduces segregation of particular metal ions and ensures compositional homogeneity. This process can overcome most of the difficulties and disadvantages that frequently occur in the alkoxides based sol-gel process.

Synthesis and luminescence properties of monodisperse spherical Y2O3 : Eu3+@SiO2 particles with core-shell structure

Y2O3: Eu3+ phosphor layers were deposited on monodisperse SiO2 particles with different sizes ( 300, 500, 900, and 1200 nm) via a sol-gel process, resulting in the formation of Y2O3: Eu3+@SiO2 core-shell particles. X-ray diffraction ( XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy ( TEM), time-resolved photoluminescence ( PL) spectra, and lifetimes were employed to characterize the Y2O3: Eu3+@SiO2 core-shell samples. The results of XRD indicated that the Y2O3: Eu3+ layers began to crystallize on the silica surfaces at 600 degrees C and the crystallinity increased with the elevation of annealing temperature until 900 degrees C. The obtained core-shell particles have perfect spherical shape with narrow size distribution and non-agglomeration. The thickness of the shells could be easily controlled by changing the number of deposition cycles ( 60 nm for three deposition cycles). Under the excitation of ultraviolet ( 250 nm), the Eu3+ ion mainly shows its characteristic red ( 611 nm, D-5(0)-F-7(2)) emissions in the core-shell particles from Y2O3: Eu3+ shells.

Size-tailored synthesis and luminescent properties of one-dimensional Gd2O3 : Eu3+ nanorods and microrods

Nearly monodisperse and well-defined one-dimensional (1D) Gd2O3:Eu3+ nanorods and microrods were successfully prepared through a large-scale and facile hydrothermal method followed by a subsequent heat treatment process, without using any catalyst or template. X-ray diffraction (XRD), thermogravimetric analysis and differential scanning calorimetry (TGA-DSC), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), photoluminescence (PL) and cathodoluminescence (CL) spectra as well as kinetic decays were used to characterize the samples. The size of the Gd2O3:Eu3+ rods could be modulated from micro- to nanoscale with the increase of pH value using ammonia solution. The as-formed product via the hydrothermal process, Gd(OH)(3):Eu3+, could transform to cubic Gd2O3:Eu3+ with the same morphology and a slight shrinking in size after a postannealing process.

Duplicating "sunlight'' from simple WOLEDs for lighting applications

Simple single-dopant white organic light-emitting devices (WOLEDs) with optimized efficiency/color quality/brightness trade-offs are developed; the white light produced shows the best color quality ever exhibited by WOLEDs at very high brightness, and is even able to duplicate the natural sunlight source.

Phosphorescence Color Tuning by Ligand, and Substituent Effects of Multifunctional Iridium(III) Cyclometalates with 9-Arylcarbazole Moieties

The synthesis, isomeric studies, and photophysical characterization of a series of multifunctional cyclometalated iridium(III) complexes containing a fluoro- or methyl-substituted 2[3-(N-plienylcarbazolyl)]pyridine molecular framework are presented. All of the complexes are thermally stable solids and highly efficient electrophosphors. The optical, electrochemical, photo-, and electrophosphorescence traits of these iridium phosphors have been studied in terms of the electronic nature and coordinating site of the aryl or pyridyl ring substituents. The correlation between the functional properties of these phosphors and the results of density functional theory calculations was made. Arising from the propensity of the electron-rich carbazolyl group to facilitate hole injection/transport, the presence of such a moiety can increase the highest-occupied molecular orbital levels and improve the charge balance in the resulting complexes relative to the parent phosphor with 2-phenylpyridine ligands. Remarkably, the excited-state properties can be manipulated through ligand and substituent effects that allow the tuning of phosphorescence energies from bluish green to deep red.

Thermoluminescence characteristics of NaSr4(BO3)(3):Ce3+ under beta-ray irradiation

The thermoluminescence (TL) properties of Ce3+ doped NaSr4(BO3)(3) phosphor under the beta-ray irradiation were reported. The polycrystalline sample was synthesized by high temperature solid-state reaction. The TL glow curve of NaSr4(BO3)(3):Ce3+ phosphor was composed of only one peak. TL kinetic parameters of NaSr4(BO3)(3):Ce3+ were deduced by the peak shape method, the activation energy (E) was 0.590 eV and the frequency factor was 1.008x10(6) s(-1). TL dose response was linear in the range of measurement. The 3-dimensional (3D) TL emission spectrum was also recorded, the emission spectrum consisted of two bands located at 441 and 479 nm respectively, corresponding to the characteristic 4f(0)5d(1)-> F-2((5/2,7/2)) transitions of the Ce3+ ion. The fading behavior of the NaSr4(BO3)(3):Ce3+ phosphor over a period of 15 d was also studied.

Uniform Lanthanide Orthoborates LnBO(3) (Ln = Gd, Nd, Sm, Eu, Tb, and Dy) Microplates: General Synthesis and Luminescence Properties

A variety of uniform lanthanide orthoborates LnBO(3) (Ln = Gd, Nd, Sm, Eu, Tb, and Dy) microplates have been successfully prepared by a general and facile conversion method. One-dimensional (ID) lanthanide hydroxides were first prepared through a simple hydrothermal process. Subsequently, uniform LnBO(3) microplates were synthesized at the expense of the ID precursors during a hydrothermal conversion process. The whole process in this method was carried out in aqueous condition without the use of any organic solvents, surfactant, or catalyst. The as-obtained rare earth ions doped GdBO3 and TbBO3 microplates show strong light emissions with different colors coming from different activator ions under ultraviolet excitation or low-voltage electron beam excitation, which might find potential applications in fields such as light phosphor powders and advanced flat panel display devices.