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 NaSc(PO):xEu phosphor (λ = 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 5d-band with increasing temperature. Our results could initiate the exploration of phosphors with zero thermal quenching for high-power LED applications.

We successfully fabricated Y2O3:RE3+ (RE = Eu, Tb, and Dy) core and core–shell nanophosphors by the molten salt method and sol–gel processes with Y2O3 core size of the order of 100~150 nm. The structural and morphological studies of the RE3+-doped Y2O3 nanophosphors are analyzed by using XRD, SEM and TEM techniques, respectively. The concentration and annealing temperature dependent structural and luminescence characteristics were studied for Y2O3:RE3+ core and core–shell nanophosphors. It is observed that the XRD peaks became narrower as annealing temperature increased in the core–shell nanophosphor. This indicates that annealing at higher temperature improves the crystallinity which in turn enhances the average crystallite size. The emission intensity and quantum yield of the Eu3+-doped Y2O3 core and core–shell nanoparticles increased significantly when annealing temperature is varied from 450 to 550 °C. No considerable variation was noticed in the case of Y2O3:Tb3+ and Y2O3:Dy3+ core and core–shell nanophosphors.

Poly-dispersed silver nanoparticles (AgNPs) were synthesized through a polyol reaction and separated by a centrifuging process to control the target plasmon resonance frequency. When the ratio between the polar side group of polyvinyl pyrrolidone and silver ions is less than 1, AgNPs of various sizes and a broad extinction spectrum can be obtained through a single process. Following the physical separation of the poly-dispersed AgNPs, both the plasmon resonance and the size distribution can be tuned depending on the centrifuging speed. Fitting the measured absorption spectrum using a Mie calculation confirms that the centrifuging method of poly-dispersed AgNPs is compatible with a simple and reliable form of fabrication for selectively extraction AgNPs with a desired size distribution.

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