Broadband and high internal quantum efficiency near-infrared phosphors obtained utilizing a chemical unit co-substitution strategy for plant lighting†

Abstract

Near-infrared phosphor-converted light-emitting diodes (NIR pc-LEDs) have been widely used in plant cultivation. However, exploring NIR phosphors with specific wavelengths and high efficiency is still the main task. In this paper, a NIR phosphor, Lu₃Ga_5−2xMg_xGe_xO₁₂ (LGMG):0.05Cr³⁺, with an emission center wavelength of 726 nm was investigated. After employing the co-substitution strategy, it was found that the strength of the crystal field in the vicinity of Cr³⁺ gradually weakened, resulting in broadening of the emission spectrum to the full width at half maximum (FWHM) of 155 nm. Notably, the developed phosphors have high IQE values and relatively better thermal stability. After optimization, the absorption spectrum of the obtained broadband near-infrared luminescent phosphor showed a high degree of matching with the absorption spectrum of the phytochrome P_FR. NIR pc-LEDs devices were successfully prepared by combining the LGMG:Cr³⁺ phosphor with commercialized blue LED chips. This phosphor has potential applications in plant lighting to promote plant growth.