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Far‐red (FR) region (beyond 700 nm) lighting sources possess special potential for plant lighting. However, it remains a challenge to obtain high‐performance Cr3+‐doped FR phosphors. This study developed a FR phosphor, Ca1.8Mg1.2Al2Ge3O12:Cr3+ (CMAGG: Cr3+), using the cation substitution strategy. Under 438 nm blue light excitation, the phosphors display FR emission centered at 720 nm with a full width at half maximum (FWHM) of 91 nm. Benefit from the favorable match with the FR phytochrome (Pfr), the phosphor is combined with InGaN blue light chips to create a FR phosphor‐converted light‐emitting diode (pc‐LED), which is used in Italian lettuce growth experiments and it results shown in a 15% increase in fresh weight and a 6.5% increase in dry weight. Notably, supplemental FR light modulated its growth morphology. The results of this study will be useful for further research on novel Cr3+‐doped FR phosphors to meet the precise spectral requirements for plant growth. [ABSTRACT FROM AUTHOR]

Cr3+‐doped phosphors are highly recognized in various fields for their remarkable luminous efficiency and spectral flexibility, including modern agriculture and horticulture. However, the shortage of suitable Cr3+‐doped phosphors for far‐red LED devices has inhibited their popularization in plant lighting. Herein, an innovative Cr3+‐doped phosphor Ca2YAl3Ge2O12:Cr3+ (CYAG:Cr3+), achieving a broad far‐red emission at 770 nm upon 450 nm blue light excitation is designed. The optimal CYAG:Cr3+ phosphor exhibits a high internal quantum yield of 78.2% and low thermal‐quenching behavior of 85%@373 K. Thus, the fabricated phosphor‐converted LEDs (pc‐LEDs) for plant far‐red lighting have a high output power of 33.3 mW and photovoltaic conversion efficiency of 11.5% at 100 mA. The potential of CYAG:Cr3+ in plant lighting is assessed by supplementing the far‐red lighting of Italian lettuce with fabricated pc‐LEDs, and the biomass of Italian lettuce is significantly increased by 33%. The successful development of CYAG:Cr3+ phosphors provides a high‐quality option for plant far‐red light devices and further stimulates the development of new Cr3+‐doped plant‐lighting phosphors. [ABSTRACT FROM AUTHOR]

Cr3+‐activated broadband near‐infrared (NIR) phosphors, featured by the octahedral coordination preference and strong absorption in visible (Vis) region, have great potential application in nondestructive assessment. It is still a challenge to develop Cr3+‐doped phosphors with the tetrahedrally coordinated Cr3+ NIR emission behavior and ultra‐wide Vis–NIR luminescence. Herein, an unusual NIR‐emitting Mg2Al4Si5O18:Cr3+ phosphor offers emission peak at 867 nm with full‐width at half‐maximum of 237 nm due to preferential occupation of the AlO4 tetrahedra by Cr3+ as demonstrated by structural and optical properties studies. Eu2+–Cr3+ energy transfer is proposed to induce ultra‐wide Vis–NIR Mg2Al4Si5O18:Eu2+,Cr3+ phosphors with more efficient NIR emission and lower thermal quenching behavior of Cr3+. The fabricated Vis–NIR phosphor‐converted light‐emitting diode is expected to be an alternative to halogen lamp in hyperspectral imaging. This work reveals the luminescence behavior of Cr3+ in tetrahedra and demonstrates the application of Mg2Al4Si5O18:Eu2+,Cr3+ phosphor in hyperspectral imaging, which will facilitate further research on NIR and Vis–NIR phosphors. [ABSTRACT FROM AUTHOR]

A series of carbon dots (CDs) grafted CaAl12O19:Mn4+ (CAO) color‐tunable hybrid phosphors have been synthesized via a facile sol‐gel method. Through the hydrolysis and condensation reactions of the silica precursor, CDs can be incorporated into highly flexible hybrid materials through combining with a CaAl12O19:Mn4+ phosphor within silica gel networks for the fabrication of flexible displays and multicolor luminescent materials. By tuning the mass ratio of CDs/CAO and by adjusting the excitation wavelength, the color of the luminescence can be systematically tailored from purplish‐red (0.504, 0.250) to greenish‐blue (0.238, 0.192). Furthermore, the temperature‐dependent luminescent properties of the CDs/CAO phosphors makes them suitable as thermometers with a wide linear temperature sensing range from 80 to 300 K. [ABSTRACT FROM AUTHOR]