No abstract

The wearable biosensing and food safety monitoring equipment requires high-brightness and thermally stable nearinfrared (NIR) phosphor-converted light emitting diodes (pc-LEDs), and the performance of these pc-LEDs is highly dependent on the properties of the NIR phosphors. This work reports an ultrawide near-infrared emission phosphor Ca 3 Sc 2 Si 3 O 12 : Cr 3+ . Under 460 nm excitation, Ca 3 Sc 2 Si 3 O 12 : Cr 3+ presents an ultrawide emission range from 650 to 900 nm. The weak absorption capacity of Cr 3+ is the main factor causing its undesirable luminous efficiency. Ce 3+ was introduced into the matrix as a role of sensitizer to contribute to the improvement of the absorption of Cr 3+ . An efficient process for energy transfer from Ce 3+ to Cr 3+ can be observed within the Ca 3 Sc 2 Si 3 O 12 codoped substance with Ce 3+ and Cr 3+ . The sample with the best doping concentration has demonstrated excellent thermal stability. At a particular temperature at 150 °C, the phenomenon of the near-infrared emission intensity is maintained at 82% at room temperature. The output power of the NIR-pc-LED based on the Ca 3 Sc 2 Si 3 O 12 : Ce 3+ , Cr 3+ and 450 nm chip reached 21.65 mW@350 mA. The excellent performance of penetrating human tissues demonstrated by the near-infrared pc-LED was observed.

A series of BaLi 2 Al 2 Si 2 N 6 (BLASN): xEu 2+ phosphors are successfully synthesized and their crystal structure and luminescence properties under varying hydrostatic pressures are reported herein. Structure variation is analyzed using in situ high-pressure X-ray diffraction and Rietveld refinements. Based on decay curves and Gaussian fitting of emission spectra, the presence of two photoluminescence centers is demonstrated. BaLi 2 Al 2 Si 2 N 6 : 0.01Eu 2+ exhibits an evident peak position shift from 532 to 567 nm with an increase in pressure to ≈20 GPa. The possible factors and mechanisms for the variations are studied in detail. At a pressure of 16 GPa, BLASN: Eu 2+ realizes a narrow yellow emission with a full width at half maximum of ≈70 nm. The addition of BLASN: Eu 2+ (16 GPa) to the commercial white light-emitting diodes combination consisting of an InGaN chip, β-SiAlON: Eu 2+ , and red K 2 SiF 6 :Mn 4+ , can increase the color gamut by ≈15%, demonstrating the promising potential of pressure-driven BLASN: Eu 2+ for wide-color gamut spectroscopy applications. Moreover, the emission shifts arising from pressure variation and the distinct color changes enable its potential utility as an optical pressure sensor; the material exhibits high pressure sensitivity (dλ/dP ≈ 1.58 nm GPa −1 ) with the advantage of visualization.

This review investigates the thermal behaviors of phosphors and summarizes phosphors with excellent thermal stabilities.

For exploring new and efficient luminescent materials, we developed an efficient narrow-band blue-emitting phosphor Eu2+ doped Na3CsMg7(PO4)6. Under near-ultraviolet light excitation, the phosphor can emit bright blue light with narrow...