Thulium Doped Phosphors Under VUV Excitation

2008 ◽  
Vol 1111 ◽  
Author(s):  
Bernard Moine ◽  
Léna Beauzamy ◽  
Richard S. Meltzer
Keyword(s):  
Excited States ◽  
High Efficiency ◽  
Emission Spectra ◽  
Quantum Yields ◽  
Relaxation Energy ◽  
Fluorescent Lamps ◽  
Emission Lifetime ◽  
Plasma Display ◽  
Quantum Cutting ◽  
Single Material

AbstractDevelopment of highly efficient mercury free fluorescent lamps and plasma display panels has been a challenging task due to the need for a combination of phosphor properties that are difficult to obtain in a single material (high efficiency, short emission lifetime and weak sensitivity to aging process under VUV excitation). Quantum cutting mechanism is a way to improve the fluorescence efficacy. Here we describe quantum cutting involving pairs of Tm3+ ions in KY3F10. Efficient excitation in the vacuum UV is initiated to the 5d state of Tm3+. This is followed by a cross relaxation energy transfer (CRET) involving the excited ion in the 5d state and nearby Tm3+ in the ground state, producing a pair of Tm3+ in excited states of the 4f13 configuration. Both ions can then emit photons. The excitation and reflection spectra are studied as a function of Tm3+ concentration and temperature. An unusual enhancement of the reflectivity at excitation wavelengths corresponding to the Tm3+ 5d absorption peaks is shown to arise from strong 5d→4f emission which is confirmed from the VUV emission spectra. The strong reduction of the integrated 5d emission intensity and shortening of its lifetime with Tm3+ concentration indicates the effective presence of the desired CRET process that is required for the first step of the quantum cutting. High Tm3+ concentrations are required for efficient quantum cutting. Whereas the CRET from the 5d state is estimated to be quite efficient, the 4f13 states of Tm3+ also undergo a strong CRET and therefore, emission from the 4f13 excited states that are created from the first step are strongly quenched at high Tm3+ concentrations. As a result, quantum yields greater than unity are not achieved.

Preparation and Photoluminescence of Nano-Sized Green Phosphors by Solution Combustion Synthesis

2012 ◽  
Vol 174-177 ◽  
pp. 1015-1018
Author(s):  
Z. Chen ◽  
Li Qiang Zhang ◽  
Miao Miao Wang ◽  
Zhi Ying Zhao ◽  
De Hui Liu ◽  
...  
Keyword(s):  
Combustion Synthesis ◽  
Emission Spectra ◽  
Solution Combustion Synthesis ◽  
Green Emission ◽  
Wide Band ◽  
Luminescent Properties ◽  
Solution Combustion ◽  
Fluorescent Lamps ◽  
Good Crystallinity ◽  
Plasma Display

By adopting a facile solution combustion synthesis (SCS) method, pure well-crystallized (Ba,Sr)MgAl10O17:Mn green phosphors were successfully prepared. The crystallinity, particle size, morphology, and luminescent properties were characterized by XRD, FE-SEM and spectrofluorometer respectively. The results indicated that the obtained phosphors have spherical morphology, good crystallinity, and strong green emission. The emission spectra of obtained nanophosphor on 147nm excitation consist of a wide band with the peak at 518nm, which corresponds to the transition from the 3d5(4T1g) excited state to the 3d5(6A1g) ground state of Mn2+. The synthesized phosphors can be efficiently excited at VUV light and have potential application in Plasma Display Panels (PDPs), 3D displays and mercury-free fluorescent lamps

High Efficiency Green Phosphor Ba9Lu2Si6O24:Tb3+: Visible Quantum Cutting via Cross-Relaxation Energy Transfers

2016 ◽  
Vol 120 (4) ◽  
pp. 2362-2370 ◽  
Author(s):  
Yongfu Liu ◽  
Jianxin Zhang ◽  
Changhua Zhang ◽  
Jun Jiang ◽  
Haochuan Jiang
Keyword(s):  
High Efficiency ◽  
Cross Relaxation ◽  
Relaxation Energy ◽  
Green Phosphor ◽  
Energy Transfers ◽  
Quantum Cutting

scholarly journals Transparent Ion-Exchange Membrane Exhibiting Intense Emission under a Specific pH Condition Based on Polypyridyl Ruthenium(II) Complex with Two Imidazophenanthroline Groups

Membranes ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 400
Author(s):  
Hajime Kamebuchi ◽  
Satoshi Tamaki ◽  
Atsushi Okazawa ◽  
Norimichi Kojima
Keyword(s):  
Ion Exchange ◽  
Emission Intensity ◽  
Density Functional ◽  
Emission Spectra ◽  
Density Functional Theory Calculations ◽  
Ion Exchange Membrane ◽  
Quantum Yields ◽  
Relative Emission Intensity ◽  
Nafion Film ◽  
Exchange Membrane

The development and the photophysical behavior of a transparent ion-exchange membrane based on a pH-sensitive polypyridyl ruthenium(II) complex, [(bpy)2RuII(H2bpib)RuII(bpy)2](ClO4)4 (bpy = 2,2′-bipyridine, H2bpib = 1,4-bis([1,10]phenanthroline[5,6-d]-imidazol-2-yl)benzene), are experimentally and theoretically reported. The emission spectra of [(bpy)2RuII(H2bpib)RuII(bpy)2]@Nafion film were observed between pH 2 and pH 11 and showed the highest relative emission intensity at pH 5 (λmaxem = 594.4 nm). The relative emission intensity of the film significantly decreased down to 75% at pH 2 and 11 compared to that of pH 5. The quantum yields (Φ) and lifetimes (τ) showed similar correlations with respect to pH, Φ = 0.13 and τ = 1237 ns at pH 5, and Φ = 0.087 and τ = 1014 ns and Φ = 0.069 and τ = 954 ns at pH 2 and pH 11, respectively. These photophysical data are overall considerably superior to those of the solution, with the radiative- (kr) and non-radiative rate constants (knr) at pH 5 estimated to be kr = 1.06 × 105 s−1 and knr = 7.03 × 105 s−1. Density functional theory calculations suggested the contribution of ligand-to-ligand- and intraligand charge transfer to the imidazolium moiety in Ru-H3bpib species, implying that the positive charge on the H3bpib ligand works as a quencher. The Ru-Hbpib species seems to enhance non-radiative deactivation by reducing the energy of the upper-lying metal-centered excited state. These would be responsible for the pH-dependent “off-on-off” emission behavior.

Fundamental physics behind high-efficiency organo-metal halide perovskite solar cells

2015 ◽  
Vol 3 (30) ◽  
pp. 15372-15385 ◽  
Author(s):  
Yu-Che Hsiao ◽  
Ting Wu ◽  
Mingxing Li ◽  
Qing Liu ◽  
Wei Qin ◽  
...  
Keyword(s):  
Solar Cells ◽  
Charge Transport ◽  
Excited States ◽  
High Efficiency ◽  
Perovskite Solar Cells ◽  
Metal Halide ◽  
Fundamental Physics ◽  
Metal Halide Perovskite ◽  
Halide Perovskite

Polarization and spin-dependent excited states and charge transport.

Preparation and Luminescence Property of LaMgAl11O19

2012 ◽  
Vol 519 ◽  
pp. 224-227 ◽  
Author(s):  
Xin Min ◽  
Ming Hao Fang ◽  
Yan Gai Liu ◽  
Zhao Hui Huang
Keyword(s):  
Solid State ◽  
Luminescence Property ◽  
Broad Band ◽  
Emission Spectra ◽  
Synthesis Temperature ◽  
Solid State Lasers ◽  
Broad Band Emission ◽  
Band Emission ◽  
Air Atmosphere ◽  
Fluorescent Lamps

Lanthanum magnesium hexaaluminate (LaMgAl11O19, LMA) has attracted much interest as its widely used in solid state lasers, TV phosphors and fluorescent lamps. In this paper, LaMgAl11O19 ceramic was pressureless sintered at 1650 °C for 10 h in air atmosphere using LaMgAl11O19 powders prepared by solid-state reaction at 1500 °C for 4 h. The result indicated that the synthesis temperature of LaMgAl11O19 powders was about 1500 °C. The LMA ceramic sample was dense and had a microstructure of platelet-like gains. The excitation spectrum shows two wide bands with the peaks at about 254 nm and 265 nm by monitoring the strongest 362 nm emission, and the emission spectra is consisted of a broad band emission with their peaks near 362 nm with a half-width about 5 nm exciting with 265 nm wavelength.

The Synthesis and Electroluminescence Properties of 4-Benzofuranyl-1,8-Naphthalimide Derivatives

2012 ◽  
Vol 557-559 ◽  
pp. 1031-1036 ◽  
Author(s):  
Jian Xin Yang ◽  
Xiang Hui Wang
Keyword(s):  
Absorption Spectra ◽  
Fluorescence Spectra ◽  
Cycloaddition Reaction ◽  
Emission Spectra ◽  
Luminescent Properties ◽  
Quantum Yields ◽  
Absorption And Fluorescence Spectra ◽  
Maximum Brightness ◽  
Maximum Emission ◽  
Mild Conditions

A series of fluorescence compounds, 4-benzofuranyl-1,8-naphthalimides, were prepared through cycloaddition reaction from 4-ethynyl-1,8-naphthalimides and o-iodophenols which catalyzed by a Pd(PPh3)2Cl2 / CuI system under mild conditions. The intermediate material, 4-ethynyl-1,8- naphthalimide, was synthesized from 4-bromo-1,8- naphthalimide and trimethylsilyl- acetylene. The absorption and fluorescence spectra of 4-benzofuranyl-1,8- naphthalimides were studied and the quantum yields were measured. The maximum UV/vis absorption spectra were in the range of 375-400 nm and the maximum emission spectra were in the range of 470-510 nm. The electro- luminescent properties were also mensurated through a doped electroluminescent device which contains 1% 1,8-naphthalimides and 99% CBP (4,4'-N,N'-dicarbazole-biphenyl), It’s shown the maximum brightness reached 3700 cd/ m2 at 22.5V.

Strongly Luminescent Tungsten Emitters with Emission Quantum Yields of up to 84 %: TADF and High‐Efficiency Molecular Tungsten OLEDs

2019 ◽  
Vol 131 (42) ◽  
pp. 15038-15042 ◽  
Author(s):  
Kaai‐Tung Chan ◽  
Tsz‐Lung Lam ◽  
Daohong Yu ◽  
Lili Du ◽  
David Lee Phillips ◽  
...  
Keyword(s):  
High Efficiency ◽  
Quantum Yields

Using phosphorescent PtAu3 clusters for superior solution-processable organic light emitting diodes with very small efficiency roll-off

2018 ◽  
Vol 6 (33) ◽  
pp. 8966-8976 ◽  
Author(s):  
Nagarajan Natarajan ◽  
Lin-Xi Shi ◽  
Hui Xiao ◽  
Jin-Yun Wang ◽  
Li-Yi Zhang ◽  
...  
Keyword(s):  
High Efficiency ◽  
Light Emitting Diodes ◽  
Organic Light Emitting Diodes ◽  
Quantum Yields ◽  
Light Emitting ◽  
Cluster Complexes ◽  
Organic Light ◽  
Solution Processable

Tetraphosphine-supported PtAu3 cluster complexes display intense phosphorescence with quantum yields of over 90% in doped films. High-efficiency solution-processable OLEDs are successfully achieved with extremely small EQE roll-off at a practical brightness over 1000 cd m−2.

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