Improving the luminescence property of the novel yellow-emitting phosphor SrLa2Sc2O7:Bi3+ with charge compensators (Li+, Na+, K+) and its application in NUV-based white LEDs.

In this work, a novel yellow-emitting phosphor SrLa2Sc2O7(SLSO):Bi3+ was synthesized by a high temperature solid-state method, with a wide coverage from 400 nm to 800 nm under near-ultraviolet (NUV) excitation and the full width at half maximum (FWHM) of up to 180 nm. The phosphor emits bright yellow light, which is observed using optical microscopy. Alkali metal (Li+, Na+, K+) ions were used as charge compensators to enhance the luminescence intensities of SrLa2Sc2O7:Bi3+. Finally, the yellow SrLa2Sc2O7:Bi3+,Li+ and blue Sr5(PO4)3Cl:Eu2+ phosphors were homogeneously mixed with silica gel and coated on a NUV light emitting diode (LED) at 370 nm to obtain white LEDs with a high color rendering index (Ra = 91.3), a low correlated color temperature (CCT = 4879 K) and color coordinates (0.34, 0.30). This work can provide a good candidate for making white LEDs.

A non-rare earth ion doped broadband emission phosphor located in NIR-II for ethanol concentration detection.

In this work, a new NIR phosphor Ca2GeO4:xCr was developed, whose emission range (1000-1700 nm) is well within NIR-II, with a full width at half maximum (FWHM) of 215 nm. Interestingly, by sintering under an air atmosphere, the Cr3+ ions in the raw material are oxidized to Cr4+, and the near-infrared light emitted by the material is not the usual luminescence of Cr3+ ions located in NIR-I, which can be attributed to the dominant substitution of Cr4+ ions doped into the lattice sites. A pc-LED fabricated with this phosphor can detect different concentrations of ethanol, which demonstrates its good potential for non-destructive testing applications.

Garnet-structured persistent luminescence phosphor Ca3Al2Ge3O12:Cr3+ for dynamic anticounterfeiting applications.

Fluorescent materials have gradually become a hot spot in the field of anti-counterfeiting. Multifunctional phosphors used in anti-counterfeiting designs still have the problems of disordered reading sequences, difficulty in detection, and easy forging. To resolve these problems, we propose a new flexible dual-mode anti-counterfeiting design using a series of phosphors Ca3Al2Ge3O12:Cr3+ (CAG) with deep red persistent luminescence peaking at 722 nm. By adjusting the doping concentration of Cr3+ from 2% to 6%, deep red persistent luminescence with different afterglow intensities and durations can be achieved. By performing a series of thermoluminescence (TL) experiments under different conditions, the defects in materials were comprehensively and systematically analyzed. The defects contributed to the deep and shallow traps; this led to an obvious improvement in its long persistent luminescence (LPL). Such a dual-mode system with flexibility and simplicity properties is a good choice not only for anti-counterfeiting, but also for multi-layer information encryption, and a series of demo experiments based on the digital tube, Moss code, QR code, bar-code, school celebration pattern, and love letter information encryption design were implemented. Their dynamic anti-counterfeiting applications have been demonstrated, which provides a new way to rationally design multi-functional luminescent materials.

Structural modulation designed a thermally robust blue-cyan emitting phosphor Y2Mg0.8Sr0.2 Al4SiO12:Eu2+ for the high color rendering index white LEDs.

In this work, the novel, to the best of our knowledge, blue-cyan Y2Mg0.8Sr0.2Al4SiO12:Eu2+ (YM0.8S0.2AS:Eu2+) phosphors were synthesized by the solid-state method. At 150°C, the emission intensity of Y2Mg0.8Sr0.2Al4SiO12:0.005Eu2+ can retain 96.38% of the relative intensity, which means that this phosphor shows high thermal stability. A white light-emitting diode (LED) device is fabricated by combining a 370 nm near ultraviolet LED chip and commercial phosphors (green, (Ba,Sr)2SiO4:Eu; red, CaSiAlN3:Eu). The white LED has an excellent property with the correlated color temperature CCT=5236K and superhigh color rendering index Ra=96.1, which indicates the potential application in white LED fields.

Near-Infrared Emitting Phosphor LaMg0.5(SnGe)0.5O3:Cr3+ for Plant Growth Applications: Crystal Structure, Luminescence, and Thermal Stability.

Corresponding to the absorption curve of plant photosensitive pigment Pfr, near-infrared light has a broad application prospect in plant lighting. In order to explore this plant growth lamp, the novel near-infrared emitting phosphor LaMg0.5Sn0.5O3:Cr3+ was synthesized, which can be efficiently excited by 467 nm blue light. There are two luminescence centers, which were proven by testing the low-temperature spectrum, the excitation spectrum at different wavelengths, and the lifetime decay curve, and the two cell sequence substitution processes were obtained by Rietveld refinements of XRD. By introducing Ge4+, its luminescence intensity has been increased 1.6 times and the intensity at 150 °C remains at almost 80% that at room temperature. Finally, two different kinds of illumination experiments for plant growth were carried out, and the feasibility of the LaMg0.5(SnGe)0.5O3:Cr3+ phosphor for plant growth was confirmed.

A single luminescence center ultra-broadband near-infrared LiScGeO4:Cr phosphor for biological tissue penetration.

In this work, in order to meet the application of near-infrared phosphor-converted light emitting diodes (pc-LEDs), an ultra-broadband emission phosphor, LiScGeO4:Cr, was synthesized. Its FWHM reaches 335 nm, and its emission spectrum ranges from 800 nm to 1650 nm, which almost covers the entire near-infrared second window (NIR-II). The broadband emission is thought to be caused by the 4T2 → 4A2 transition of the Cr3+ ion. This transition occurs due to the olivine structure of the crystal, which causes the Cr3+ ions to inhabit a low-symmetric crystal field, and the crystal field strength is very weak. NIR pc-LEDs were fabricated by combining a 460 nm blue LED with this phosphor, which penetrates 4 cm thick beef. The results indicate that there may be a potential application for this phosphor in the field of biological tissue penetration and non-destructive testing.