Recently, infrared (IR) light-emitting diodes (LEDs) have attracted considerable interest in the research field worldwide. IR phosphors, the basic materials utilized in LEDs, have become a research hotspot as well. Here, we introduce the high-quantum-efficiency IR ScBO 3 :Cr 3+ phosphor, which provides a spectral range of emission from 700 to 1000 nm with a peak maximum at 800 nm. Electron paramagnetic resonance spectroscopy, with high element selectivity, was used to elucidate the unusual small peak in the photoluminescence spectrum. Phonon structure and electron−lattice interaction were well observed and discussed via temperature-dependent measurements. Moreover, the high quantum efficiency of 72.8% was achieved. To evaluate their potential practical application, phosphor-converted LED packages were designed, which revealed high stability and high output power of 39.11 mW. Furthermore, the fabricated IR LED demonstrated a remarkable ability to penetrate biological tissues. This study provides insights into the luminescent properties and the practical applications of IR LEDs.
We aim to conduct a complete study on the unexpected structure evolution behavior in Cr 3+ -doped phosphors. A series of Ga 2−x Sc x O 3 :Cr 3+ phosphors are successfully synthesized and confirmed through structural studies, while the lattice parameters change unexpectedly. The unique partial substitution (∼87%) of Sc 3+ in the octahedral site is demonstrated via Rietveld refinement. Therefore, the bond valence sum calculation explains the reason for this particular Sc 3+ concentration. The photoluminescent bandwidth and electron−lattice coupling energy initially increase and then decrease, implying an inhomogeneous broadening effect. Time-resolved spectra and electron paramagnetic resonance are utilized to further examine the subtle change in the microstructures and the second coordination sphere effect of Cr 3+ . Ga 1.594 Sc 0.4 O 3 :0.006Cr 3+ exhibits high internal quantum efficiency (99%) and high phosphor-converted light-emitting diode output power (66.09 mW), demonstrating its capability as an outstanding infrared phosphor. This work will motivate further research on unexpected partial substitution during the solid solution process.
Portable near-infrared (NIR) light sources are in high demand for applications in spectroscopy, night vision, bioimaging, and many others. Typical phosphor designs feature isolated Cr 3+ ion centers, and it is challenging to design broadband NIR phosphors based on Cr 3+ −Cr 3+ pairs. Here, we explore the solidsolution series SrAl 11.88−x Ga x O 19 :0.12Cr 3+ (x = 0, 2, 4, 6, 8, 10, and 12) as phosphors featuring Cr 3+ −Cr 3+ pairs and evaluate structure−property relations within the series. We establish the incorporation of Ga within the magentoplumbite-type structure at five distinct crystallographic sites and evaluate the effect of this incorporation on the Cr 3+ −Cr 3+ ion pair proximity. Electron paramagnetic measurements reveal the presence of both isolated Cr 3+ and Cr 3+ − Cr 3+ pairs, resulting in NIR luminescence at approximately 650−1050 nm. Unexpectedly, the origin of broadband NIR luminescence with a peak within the range 740−820 nm is related to the Cr 3+ −Cr 3+ ion pair. We demonstrate the application of the SrAl 5.88 Ga 6 O 19 :0.12Cr 3+ phosphor, which possesses an internal quantum efficiency of ∼85%, a radiant flux of ∼95 mW, and zero thermal quenching up to 500 K. This work provides a further understanding of spectral shifts in phosphor solid solutions and in particular the application of the magentoplumbites as promising next-generation NIR phosphor host systems.
Phosphor-converted light-emitting diodes (LEDs) have recently become a promising candidate for next-generation agricultural and horticultural-use devices. In principle, they can overcome the limitations of regular daily sunshine. Here, the principle...
Mini-light-emitting diodes (mini-LEDs) are regarded as a promising light source for future high-end electronic products. Phosphors with a small size and high efficiency have been reported to achieve this goal. Here, we demonstrate that an easily synthesized Ga 2 O 3 :Cr 3+ -embedded mesoporous silica nanoparticle (GOC@ MSN) is an outstanding nanophosphor with a superb internal quantum efficiency (91.4%) and a good thermal stability. Structural studies have determined the mesostructure and intermolecular transfer of free electrons. Meanwhile, spectral studies have demonstrated detailed luminescent and thermal properties. A mini-LED package using a GOC@MSN nanophosphor and covering 650−900 nm exhibits its potential for practical applications. This work provides insight into the space-limited ship-in-a-bottle synthesis method for achieving a high quantum efficiency in nanosized phosphors and motivates further research on luminescent materials that use mini-LEDs.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.