Cyan-emitting phosphors are important
for near-ultraviolet (NUV)
light-emitting diodes (LEDs) to gain high-quality white lighting.
In the present work, a Bi3+-doped BaScO2F, R+ (R = Na, K, Rb) perovskite, which emits 506 nm cyan-green
light under 360 or 415 nm excitation, is obtained via a high-temperature
solid-state method for the first time. The obtained perovskite shows
improved photoluminescence and thermal stability due to the charge
compensation of Na+, K+, and Rb+ co-doping.
Its spectral broadening is attributed to two centers Bi (1) and Bi
(2), which are caused by the zone-boundary octahedral tilting due
to the substitution of Bi3+ for the larger Ba2+. Employing the blend phosphors of Ba0.998ScO2F:0.001Bi3+,0.001K+ and the commercial BAM:Eu2+, YAG:Ce3+, and CaAlSiN3:Eu2+, a full-spectrum white LED device with R
a = 96 and CCT = 4434 K was fabricated with a 360 nm NUV chip. Interestingly,
a novel strategy is proposed: the cyan-green Ba0.998ScO2F:0.001Bi3+,0.001K+ and orange Sr3SiO5:Eu2+ phosphors were packaged with
a 415 nm NUV chip to produce the white LED with R
a = 85 and CCT = 4811 K.
As a luminous center, Mn2+ has the advantages of high efficiency, safety, and cheap, which has been widely used to improve the color rendering index of garnet structure phosphors. Although,...
Molybdenum and tungsten disulfide nanoplates were produced by self-propagating high-temperature synthesis in argon atmosphere. This method provides an easy way to produce MoS2 and WS2 from nanoplates up to single- and several layers. The Raman peak intensities corresponding to in-plane E12g and out-of-plane A1g vibration modes and their shifts strongly depend on the thicknesses of the MoS2 and WS2 platelets indicating size-dependent scaling laws and properties. An electron beam irradiation of MoS2 and WS2 powders leads to an occurrence of pulsed cathodoluminescence (PCL) spectra at 575 nm (2.15 eV) and 550 nm (2.25 eV) characteristic to their intrinsic band gaps. For the combination of MoS2 and WS2 nanopowders, a PCL shoulder at 430 nm (2.88 eV) was observed, which is explained by the radiative electron-hole recombination at the MoS2/WS2 grain boundaries. The luminescence decay kinetics of the MoS2/WS2 nanoplates appears to be slower than for individual MoS2 and WS2 platelets due to a spatial separation of electrons and holes at MoS2/WS2 junction resulting in extension of recombination time.
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