Novel Cr³⁺‐Doped Garnet Phosphor with Broadband Efficient Far‐Red Emission for Photochrome Matching Plant‐Lighting

Abstract

Abstract Cr 3+ ‐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 Cr 3+ ‐doped phosphors for far‐red LED devices has inhibited their popularization in plant lighting. Herein, an innovative Cr 3+ ‐doped phosphor Ca 2 YAl 3 Ge 2 O 12 :Cr 3+ (CYAG:Cr 3+ ), achieving a broad far‐red emission at 770 nm upon 450 nm blue light excitation is designed. The optimal CYAG:Cr 3+ 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:Cr 3+ 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:Cr 3+ phosphors provides a high‐quality option for plant far‐red light devices and further stimulates the development of new Cr 3+ ‐doped plant‐lighting phosphors.