Ce-doped garnet phosphors play an important role in the white light-emitting diode (LED) family. In the past years, a lot of trial-and-error experiments guided by experience to discover phosphors suitable for white LEDs have been presented. The working temperature of phosphors may reach 200 °C in white LEDs, and so, the exploration of phosphors with excellent thermal stability at the desired wavelength continues to be a challenge. In the present study, to discover novel cyan−green garnet:Ce phosphors, wavelength and thermal stability machine learning models were built by constructing reasonable features. Among the 171,636 compounds with garnet structures predicted by our models, 25 samples were selected for preparation and characterization by multiobjective optimization based on active learning.

High-efficiency long-wavelength emission near-infrared (NIR) phosphors are the key to next-generation LED light sources. However, high-efficiency phosphors usually exhibit narrow-band emission at shorter wavelengths due to the crystal field intensity. In this paper, we utilize multi-objective optimization to discover the NIR phosphor Gd 3 Mg 0.5 Al 1.5 Ga 2.5 Ge 0.5 O 12 :0.04Cr 3+ . It exhibits a broadband NIR emission from 650 to 1100 nm peaking at 763 nm, with a full width at half maximum (FWHM) of 150 nm, an internal quantum efficiency (IQE)/external quantum efficiency (EQE) of 90%/53.1%, and good thermal stability (85.3% @ 150 °C). The packaging results show that ∼53.2 mW of output power is achieved at 915 mW input power, which suggests promising applications for NIR pc-LED. Our approach is based on the data of emission wavelength (WL) and IQE for garnet:Cr NIR phosphors to construct machine learning models. An active learning strategy is used to make tradeoffs between WL and IQE, and we are able to find the targeted phosphor after only four iterations of synthesis and characterization.

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Broadband near-infrared (NIR) phosphors are the critical component of phosphor converted NIR light-emitting diode (LED) light sources. However, there are still a lack of NIR phosphors with excellent external quantum efficiency (EQE) and thermal stability. Here, we report a highly efficient broadband NIR phosphor Y3Ga3MgSiO12: Cr3+. The optimized phosphor yields an internal quantum efficiency (IQE) and an EQE of 79.9 and 33.7%, respectively. The integrated emission intensity still remains at 84.4% of that at room temperature when heated to 423 K. A broadband NIR LED lamp was made by combining as-prepared phosphor and a blue InGaN LED chip, which shows an output power of 89.8 mW with a photoelectric conversion efficiency of 17.1% driven at 525 mW input power. Our research provides a promising NIR phosphor with high efficiency broadband for the NIR light source.

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