Constructing efficient and thermally-stable far red emitting phosphor with excellent response to phytochrome Pfr for indoor agriculture

Cr 3+ -doped phosphors still suffer from limitations, such as low quantum efficiency, poor thermal stability, and spectral peak mismatch, restricting their application in pc-LEDs for indoor agriculture. In this study, cation Sc substitution strategy was applied in Y 3 Ga 5 O 12 . Given that the emission location, an efficient far-red (FR) phosphor Y 3 ScGa 4 O 12 :Cr 3+ (YSGO:Cr 3+ ) with high matching to phytochrome was constructed, under 442 nm excitation, realizing FR emission (728 nm) with FWHM 99 nm. The optimized phosphor demonstrates exceptionally high internal quantum efficiency of 95.4 % and excellent thermal quenching property (91.6 %@423 K). Furthermore, a fabricated phosphor-converted light-emitting diode (pc-LED), combining YSGO:0.07 Cr 3+ with a 450 nm chip, delivers FR output power of 36.74 mW with a photoelectric conversion efficiency (PCE) of 12.8 % at 100 mA, demonstrating ultra-low quenching rate (<5 % intensity loss after 3 months operation). A supplemental lighting model for lettuce growth was constructed, which significantly improves in physiological parameters, confirming the great potential of this phosphor for plant lighting applications.