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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 Cr3+ ion centers, and it is challenging to design broadband NIR phosphors based on Cr3+-Cr3+ pairs. Here, we explore the solid-solution series SrAl11.88-xGaxO19:0.12Cr3+ (x = 0, 2, 4, 6, 8, 10, and 12) as phosphors featuring Cr3+-Cr3+ 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 Cr3+-Cr3+ ion pair proximity. Electron paramagnetic measurements reveal the presence of both isolated Cr3+ and Cr3+-Cr3+ 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 Cr3+-Cr3+ ion pair. We demonstrate the application of the SrAl5.88Ga6O19:0.12Cr3+ 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.

This work was financially supported by the Advanced Research Center of Green Materials Science and Technology from The Featured Area Research Center Program within the framework of the Higher Education Sprout Project by the Ministry of Education (107L9006), the Ministry of Science and Technology in Taiwan (Contracts MOST 109-2113-M-002-020-MY3, MOST 107-2113-M-002-008-MY3, MOST 110-2923-M-002-017-MY3, MOST 107-2923-M-002-004-MY3, and MOST 107-3017-F-002-001), the National Science Center Poland Grant Opus (nos. 2016/23/B/ST3/03911 and 2019/33/B/ST3/00406), and the National Center for Research and Development Poland Grant (no. PL-TW/VIII/1/2021). Cs4PbI6, as a rarely investigated member of the Cs4PbI6(X is a halogen element) family, has been successfully synthesized at low temperatures, and the synthetic conditions have been optimized. Metal iodides such as LiI, KI, NiI2, CoI2, and ZnI2, as additives, play an important role in enhancing the formation of the Cs4PbI6 microcrystals. ZnI2 with the lowest dissociation energy is the most efficient additive to supply iodide ions, and its amount of addition has also been optimized. Strong red to near-infrared (NIR) emission properties have been detected, and its optical emission centers have been identified to be numerous embedded perovskite-type α-CsPbI3 nanocrystallites (∼5 nm in diameter) based on investigations of temperature- and pressure-dependent photoluminescent properties. High-resolution transmission electron microscopy was used to detect these hidden nanoparticles, although the material was highly beam-sensitive and confirmed a “raisin bread”-like structure of the Cs4PbI6 crystals. A NIR mini-LED for the biological application has been successfully fabricated using as-synthesized Cs4PbI6 crystals. This work provides information for the future development of infrared fluorescent nanoscale perovskite materials. Postprint

A chemical and mechanical pressure-induced photoluminescence tuning method was developed through the structural evolution and hydrostatic pressure involving phase transition. A series of Ga1.98–xAl...

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 achiev...

We aim to conduct a complete study on the unexpected structure evolution behavior in Cr3+-doped phosphors. A series of Ga2–xScxO3:Cr3+ phosphors are successfully synthesized and confirmed through s...

Indoor recirculating aquaculture systems make light control possible and enable the usage of specific coloured lights to promote the growth and immunity of aquaculture species. Five different LED wavelengths (white light, red light [622 nm], green light [517 nm], blue light [467 nm], and dark) were used in this study to evaluate growth and immunity in the glass eel stage of two high-valued anguillid species, Japanese eel ( Anguilla japonica ) and giant mottled eel ( A. marmorata ). There were no significant differences in growth of the Japanese eel among the groups after ­12 weeks of feeding (P > 0.05); the survival rate of each group was over 95%. The giant mottled eel showed better growth in total length and body weight in the red light and dark groups (P < 0.05). Expression levels of immune-related genes were not significantly different between each group of the Japanese eel and the giant mottled eel (P > 0.05). The growth of the Japanese glass eel was not significantly sensitive to different LED wavelengths, while the giant mottled glass eel showed better growth under red light and dark environments. Neither eel species showed significant differences in innate immunity under different LED wavelengths.

Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has emerged as a serious threat to human health worldwide. The inactivation of SARS-CoV-2 on object surfaces and in the indoor air might help to halt the COVID-19 pandemic. Far-ultraviolet light (UVC) disinfection has been proven to be highly effective against viruses and bacteria. To understand the wavelength and duration of UVC radiation required for SARS-CoV-2 inactivation, we examined the efficacy of UVC light prototype devices with the wavelengths of 275, 254, and 222 nm. The disinfection effectiveness was determined by cell-based assays including the median tissue culture infectious dose (TCID50) and an immunofluorescent assay on African green monkey kidney epithelial Vero E6 cells. Among the three prototypes, the UVC LED (275 nm) had the best virucidal activity with a log-reduction value (LRV) &gt, 6 after 10 s of exposure. The mercury lamp (254 nm) reached similar virucidal activity after 20 s of exposure. However, the excimer lamp (222 nm) showed limited anti-SARS-CoV-2 activity with a LRV &lt, 2 after 40 s of exposure. Overall, in comparison, the UVC LED (275 nm) exhibited superior SARS-CoV-2 disinfection activity than the mercury lamp (254 nm) and the excimer lamp (222 nm).

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...

Broadband near-infrared CuInS2/ZnS quantum dots with up to 94.8% quantum yield were synthesized with fast precursor decomposition leading to monomer conversion improvement. In the mini-LED package, the device showed high power efficiency and stability was also demonstrated with a penetration test and vein imaging showing its potential biomedical application in the theranostics field.

Phosphor-converted light-emitting diodes (LEDs) have recently become a promising candidate for next-generation devices used in agriculture and horticulture. In principle, they can overcome the limitations of regular daily sunshine. Here, the principle of LED-promoted plant growth was demonstrated by using the Ga2O3:Cr3+ phosphor with an extremely high quantum yield of 92.4%. The detailed structural and luminescent properties were characterized using X-ray diffraction, temperature-dependent photoluminescence, and pressure-dependent photoluminescence. The results reveal the unique two electronic spin-forbidden transition emissions (R1 and R2) of the Ga2O3:Cr3+ phosphor. Plant growth experiments were also conducted to evaluate the practical applications of the as-prepared phosphors, showing that they exhibit obvious positive effects on plants. This work reveals the important role of LEDs in agriculture and horticulture, as well as their potential practical applications.

Narrowing the size of near-infrared (NIR) spectrometers has gained substantial interest among researchers in both scientific and nonscientific communities due to the inherent usage in the nondestru...

Cs

Narrowband green phosphors with high quantum efficiency are required for backlighting white light-emitting diode (WLED) devices. Materials from the A[Li3SiO4]4:Eu2+ family have recently been proposed as having superior properties to industry-standard β-SiAlON green phosphors. Here, we show that a cheap, easily synthesized host NaK2Li[Li3SiO4]4 (NKLLSO) doped with a mixture of Eu2+ and Eu3+ is an outstanding narrowband green phosphor, with an external quantum efficiency of 51% and superb thermal stability (97.1% of room-temperature performance at 150 °C). Structural studies reveal that green emission occurs from two Eu2+ sites, while Eu3+ introduces a high concentration of vacancies that may suppress quenching from energy transfer between Eu2+ sites. A WLED package constructed using our NKLLSO phosphor shows extremely high color vividness, competitive with a β-SiAlON comparator. This work will stimulate further research on efficient green phosphors for practical WLED devices.

Near-infrared (NIR) phosphors are fascinating materials that have numerous applications in diverse fields. In this study, a series of La3Ga5GeO14:Cr3+ phosphors, which was incorporated with Sn4+, B...

Broadband near-infrared CuInS

Light-emitting diodes break barriers of size and performance for displays. With devices becoming smaller, the materials also need to get smaller. Chromium(III)-doped oxide phosphors, which emit near-infrared (NIR) light, have recently been used in small electronic devices. In this work, mesoporous silica nanoparticles were used as nanocarriers. The nanophosphor ZnGa2 O4 :Cr3+ ,Sn4+ formed in the mesopore after sintering. Good dispersity and morphology were performed with average diameters of 71±7 nm. It emitted light at 600-850 nm; the intensity was optimized by tuning the doping ratio of Cr3+ and Sn4+ . Meanwhile, the light conversion efficiency increased from 7.8 % to 37 % and the molar concentration increased from 0.125 m to 0.5 m. The higher radiant flux of 3.3 mW was obtained by operating an input current of 45 mA. However, the NIR nanophosphor showed good performance on mini light-emitting diode chips.

The near-infrared (NIR) light source is desirable for real-time nondestructive examination applications, which include the analysis of foodstuffs, health monitoring, iris recognition, and infrared cameras. The emission spectra of such an infrared light source should also be as broad as possible for effective performance, in view of the fact that the broad absorption and reflection of light by the organic elements present in foodstuffs and human health fall in the blue and NIR regions of the electromagnetic spectrum, respectively. In this letter, a blue light-emitting diode (LED) excitable super broadband NIR phosphor light source is developed with a high fwhm of 330 nm and radiant flux of 18.2 mW for the first time. The observation of super-broad-band luminescence from two distinct luminescence centers is studied and evidenced by electron paramagnetic resonance, X-ray absorption near-edge structure, steady-state luminescence, and time-resolved luminescence at ambient and high-pressure environments. Finall...

Light-emitting diodes break barriers of size and performance for displays. With devices becoming smaller, the materials also need to get smaller. Chromium(III)-doped oxide phosphors, which emit near-infrared (NIR) light, have recently been used in small electronic devices. In this work, mesoporous silica nanoparticles were used as nanocarriers. The nanophosphor ZnGa