Wearable biosensing and food safety inspection devices with high thermal stability, high brightness, and broad near-infrared (NIR) phosphor-converted light-emitting diodes (pc-LEDs) could accelerate the next-generation NIR light applications. In this work, NIR La 3−x Gd x Ga 5 GeO 14 :Cr 3+ (x = 0 to 1.5) phosphors were successfully fabricated by a high-temperature solid-state method. Here, by doping Gd 3+ ions into the La 3+ sites in the La 3 Ga 5 GeO 14 matrix, a 7.9-fold increase in the photoluminescence (PL) intensity of the Cr 3+ ions, as well as a remarkably broadened full width at half-maximum (FWHM) of the corresponding PL spectra, is achieved. The enhancements in the PL, PLE intensity, and FWHM are attributed to the suppression of the nonradiative transition process of Cr 3+ when Gd 3+ ions are doped into the host, which can be demonstrated by the decay curves. Moreover, the La 1.5 Gd 1.5 Ga 5 GeO 14 :Cr 3+ phosphor displays an abnormally negative thermal phenomenon that the integral PL intensity reaches 131% of the initial intensity when the ambient temperature increases to 160 °C. Finally, the broadband NIR pc-LED was fabricated based on the as-explored La 1.5 Gd 1.5 Ga 5 GeO 14 :Cr 3+ phosphors combined with a 460 nm chip, and the potential applications for the broadband NIR pc-LEDs were discussed in detail.

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Far-red light is very important for plant photomorphogenesis. Herein, we report a novel Ba 2 LuNbO 6 :Mn 4+ far-red phosphor by high temperature solid state method. Its crystal structure and optical property are systematically studied. The as-fabricated Ba 2 LuNbO 6 :Mn 4+ phosphor exhibits broad excitation bands ranging from 300 to 550 nm, attributed from the d-d transitions of Mn 4+ , and emits expected far-red light with the center of 698 nm ( 2 E g → 4 A 2g ) under 370 nm UV irradiation. Furthermore, the temperature-dependent photoluminescence (PL) intensity and the activation energy of Mn 4+ are investigated in detail. A far-red pc-LED is fabricated by combining the Ba 2 LuNbO 6 :Mn 4+ and 365 nm UV chip, showing a good overlap with the absorption data of phytochrome P FR . Surprisingly, by introducing secondary cation ion Gd 3+ , the far-red PL intensity is obviously enhanced because of crystal field adjusted and nephelauxetic effect. Finally, our work supplies a novel far-red candidate phosphor for indoor plant cultivation.

Thanks to the unique sharp red emission spectra and broadband excitation, Mn 4+ ions activated oxide host matrixes exhibit fascinating potential application in white light-emitting diodes (wLEDs). In this work, Mn 4+ activated LaGaO 3 with a perovskite structure were successfully synthesized via a solid state reaction, which exhibits a near infrared (NIR) emission with high brightness, locating around 710 nm. Moreover, the introduction of the transition metal Bi 3+ ions contributes to a remarkable improved luminescence output of Mn 4+ ions with enhanced internal quantum efficiency performance.