Catalogue Search | MBRL
Are you sure you want to remove the book from the shelf?
{{itemTitle}}
8,218
result(s) for
"phosphors"
Sort by:
K2SiF6:Mn4+ phosphor: recommendation for improving LO and D-CCT of the 7700K RPW-LEDs
In this paper, we propose a new recommendation for improving lumen output (LO) and CCT deviation (D-CCT) of the 7700 K RPW-LEDs by K2SiF6:Mn4+ red phosphor. Based on Light Tool and Mat Lab simulation software, we can see that the D-CCT and LO can be improved significantly, but the CQS and CRI have a slight decrease with increasing the concentration of the red phosphor. Besides, the analytical and simulation results agree well with each other.
Journal Article
Recent progress in advanced optical materials based on gadolinium aluminate garnet (Gd3Al5O12)
This review article summarizes the recent achievements in stabilization of the metastable lattice of gadolinium aluminate garnet (Gd
3
Al
5
O
12
, GAG) and the related developments of advanced optical materials, including down-conversion phosphors, up-conversion phosphors, transparent ceramics, and single crystals. Whenever possible, the materials are compared with their better known YAG and LuAG counterparts to demonstrate the merits of the GAG host. It is shown that novel emission features and significantly improved luminescence can be attained for a number of phosphor systems with the more covalent GAG lattice and the efficient energy transfer from Gd
3+
to the activator. Ce
3+
doped GAG-based single crystals and transparent ceramics are also shown to simultaneously possess the advantages of high theoretical density, fast scintillation decay, and high light yields, and hold great potential as scintillators for a wide range of applications. The unresolved issues are also pointed out.
Journal Article
Efficient and bright white light-emitting diodes based on single-layer heterophase halide perovskites
At present, electric lighting accounts for ~15% of global power consumption and thus the adoption of efficient, low-cost lighting technologies is important. Halide perovskites have been shown to be good emitters of pure red, green and blue light, but an efficient source of broadband white electroluminescence suitable for lighting applications is desirable. Here, we report a white light-emitting diode (LED) strategy based on solution-processed heterophase halide perovskites that, unlike GaN white LEDs, feature only one broadband emissive layer and no phosphor. Our LEDs operate with a peak luminance of 12,200 cd m−2 at a bias of 6.6 V and a maximum external quantum efficiency of 6.5% at a current density of 8.3 mA cm−2. Systematic in situ and ex situ characterizations reveal that the mechanism of efficient electroluminescence is charge injection into the α phase of CsPbI3, α to δ charge transfer and α–δ balanced radiative recombination. Future advances in fabrication technology and mechanistic understanding should lead to further improvements in device efficiency and luminance.Heterophase CsPbI3 perovskite gives rise to bright white phosphor-free LEDs.
Journal Article
Efficient and stable emission of warm-white light from lead-free halide double perovskites
Lighting accounts for one-fifth of global electricity consumption
1
. Single materials with efficient and stable white-light emission are ideal for lighting applications, but photon emission covering the entire visible spectrum is difficult to achieve using a single material. Metal halide perovskites have outstanding emission properties
2
,
3
; however, the best-performing materials of this type contain lead and have unsatisfactory stability. Here we report a lead-free double perovskite that exhibits efficient and stable white-light emission via self-trapped excitons that originate from the Jahn–Teller distortion of the AgCl
6
octahedron in the excited state. By alloying sodium cations into Cs
2
AgInCl
6
, we break the dark transition (the inversion-symmetry-induced parity-forbidden transition) by manipulating the parity of the wavefunction of the self-trapped exciton and reduce the electronic dimensionality of the semiconductor
4
. This leads to an increase in photoluminescence efficiency by three orders of magnitude compared to pure Cs
2
AgInCl
6
. The optimally alloyed Cs
2
(Ag
0.60
Na
0.40
)InCl
6
with 0.04 per cent bismuth doping emits warm-white light with 86 ± 5 per cent quantum efficiency and works for over 1,000 hours. We anticipate that these results will stimulate research on single-emitter-based white-light-emitting phosphors and diodes for next-generation lighting and display technologies.
After alloying with metal cations, a lead-free halide double perovskite shows stable performance and remarkably efficient white-light emission, with possible applications in lighting and display technologies.
Journal Article
A zero-thermal-quenching phosphor
Phosphor-converted white light-emitting diodes (pc-WLEDs) are efficient light sources used in lighting, high-tech displays, and electronic devices. One of the most significant challenges of pc-WLEDs is the thermal quenching, in which the phosphor suffers from emission loss with increasing temperature during high-power LED operation. Here, we report a blue-emitting Na
3–2
x
Sc
2
(PO
4
)
3
:
x
Eu
2+
phosphor (
λ
em
= 453 nm) that does not exhibit thermal quenching even up to 200 °C. This phenomenon of zero thermal quenching originates from the ability of the phosphor to compensate the emission losses and therefore sustain the luminescence with increasing temperature. The findings are explained by polymorphic modification and possible energy transfer from electron–hole pairs at the thermally activated defect levels to the Eu
2+
5
d
-band with increasing temperature. Our results could initiate the exploration of phosphors with zero thermal quenching for high-power LED applications.
A blue-emitting phosphor without thermal quenching is reported. The emission losses at high temperatures are compensated by a counter mechanism, originating in energy transfer between electron–hole pairs and thermally activated defect levels.
Journal Article
Near-infrared organic light-emitting diodes with very high external quantum efficiency and radiance
Bright and efficient organic emitters of near-infrared light would be of use in applications ranging from biological imaging and medical therapy to night-vision devices. Here we report how a new class of Pt(
II
) complex phosphors have enabled the fabrication of organic light-emitting diodes that emit light at 740 nm with very high efficiency and radiance due to a high photoluminescence quantum yield of ∼81% and a highly preferred horizontal dipole orientation. The best devices exhibited an external quantum efficiency of 24 ± 1% in a normal planar organic light-emitting diode structure. The incorporation of a light out-coupling hemisphere structure further boosts the external quantum efficiency up to 55 ± 3%.
New design of Pt(
II
) phosphors yield near-infrared organic light-emitting diodes with high efficiency and brightness.
Journal Article
Research Progress and Development of Near-Infrared Phosphors
Near-infrared (NIR) light has attracted considerable attention in diverse applications, such as food testing, security monitoring, and modern agriculture. Herein, the advanced applications of NIR light, as well as various devices to realize NIR light, have been described. Among the diverse NIR light source devices, the NIR phosphor-converted light-emitting diode (pc-LED), serving as a new-generation NIR light source, has obtained attention due to its wavelength-tunable behavior and low-cost. As one of the key materials of the NIR pc-LED, a series of NIR phosphors have been summarized depending on the type of luminescence center. Meanwhile, the characteristic transitions and luminescence properties of the above phosphors are illustrated in detail. In addition, the status quo of NIR pc-LEDs, as well as the potential problems and future developments of NIR phosphors and applications have also been discussed.
Journal Article
A new Tm3+-doped ZnLaB5O10 borate blue-emitting phosphor for w-LEDs
A blue-luminescent Tm3+-activated ZnLaB5O10 material was initially synthesized via thermal solid-state reactions. Structural characterization and optical evaluations confirmed phase homogeneity and radiative characteristics of the crystalline products. Experimental data identified 3 mol% Tm3+ doping (x=0.03) as the critical concentration threshold before emission efficiency decline. Mechanistic studies revealed that multipolar electrical interactions dominate energy dissipation processes in over-doped systems. The optimized compound exhibited intense blue emission with CIE chromaticity values (0.1803, 0.1007), demonstrating suitability as a blueconversion material in w-LED architectures.
Journal Article