A highly efficient and suitable spectral profile Cr³⁺-doped garnet near-infrared emitting phosphor for regulating photomorphogenesis of plants

Far-red/phytochrome (P_FR) plays a key role in photomorphogenesis of plants. However, how to obtain a near-infrared (NIR) emitting phosphor with high external quantum efficiency (EQE), suitable spectral profile, and low thermal quenching remains a huge challenge. Herein, a NIR phosphor, Gd_2.4Lu_0.6Ga₄AlO₁₂:Cr³⁺,H₃BO₃ (GLGA:Cr³⁺) was developed via regulating the crystal field environment and adding fluxes, which exhibits a peak maximum at 728 nm with a relatively narrow full-width at half maximum (FWHM) of 107 nm, matching well with the absorption band of P_FR. Upon 450 nm excitation, the internal quantum efficiency (IQE) and EQE of the optimal phosphor are 90.3% and 32.0%, respectively. At 423 K, the integrated emission intensity of the investigated phosphor is about 75% of that at room temperature. Benefiting from the excellent optical performance, a NIR phosphor-converted light-emitting diode (pc-LED) was fabricated, which shows a NIR output power of 505.99 mW and photoelectric conversion efficiency of 11.24% at 300 mA. Moreover, plant growth experiments demonstrate that the biomass of pea seedlings is increased by 67.72% under supplementary NIR light irradiation. The findings of this research will motivate further research on new Cr³⁺-doped NIR phosphors for regulating photomorphogenesis of plants.